This PDF file contains the front matter associated with SPIE Proceedings Volume 9143, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

The James Webb Space Telescope (JWST) is a large aperture (6.5 meter), cryogenic space telescope with a suite of near and mid-infrared instruments covering the wavelength range of 0.6 μm - 28 μm. JWST’s primary science goal is to detect and characterize the first galaxies. It will also study the assembly of galaxies, star formation, and the formation of evolution of planetary systems. JWST is a segmented mirror telescope operating at ~40K, a temperature achieved by passive cooling of the observatory, via a large, 5-layer membrane-based sunshield. We present an overview of the observatory systems design, the science instruments and the mission science objectives. With the completion of the Spacecraft Critical Design Review, the spacecraft has also fully transitioned to fabrication. We will discuss recent highlights associated with the Observatory, including completion and delivery of the primary mirror segments, delivery of the primary mirror backplane and its wings, and the delivery of five template membrane layers. We will also summarize the current predicted performance of the telescope, including stray light, pointing and image quality following the completion of the final design review. Finally, the current schedule through to launch will be presented with a summary of integration and test activities planned when the science payload is delivered to Northrop Grumman following cryo-optical testing at the Johns Space Flight Center.

Significant progress has been made in the development of the Optical Telescope Element (OTE) for the James Webb Space Telescope (JWST) Observatory. All of the mirror assemblies are complete and delivered. The composite Primary Mirror Backplane Support Structure (PMBSS) has completed assembly and in Static Load testing. All the deployment mechanisms have completed their qualification programs. This paper will discuss the current status of all the OTE components and the plan forward to completion.

The flight components for the James Webb Space Telescope optical system are built and the assembly and integration of the telescope and instrument system is in progress. The optical performance for JWST has been updated using the as-built performance of the individual components; updated predictions for alignment as the assembly and integration process has matured; and updated performance predictions for the flight stability contributors: temperature stability driven thermo-elastic deformation and dynamic response stability to flight disturbances. These updates flow from the collective product of several groups on the JWST team.

The James Webb Space Telescope (JWST) is a 6.5m, segmented, IR telescope that will explore the first light of the universe after the big bang. 2014 is an incredible year for the Telescope Alignment, Integration, and Test portion of the program. Long awaited and planned, the two segment Pathfinder telescope will be built and the Optical Ground Support Equipment (OGSE) will be integrated into the large cryo-vacuum chamber at the Johnson Spaceflight Center. The current status of the integration equipment and the demonstrations leading up to the flight-like Pathfinder telescope will be provided as the first step to the final verification of the complex cryo test equipment. The plans and status of bringing the OGSE on-line and ready for a series of risk reduction cryo tests starting in 2015 on the Pathfinder Telescope will also be presented.

The James Webb Space Telescope (JWST) requires testing of the full optical system in a cryogenic vacuum environment before launch. Challenges with the telescope architecture and the test environment lead to placing removable optical test sources at the Cassegrain intermediate focus of the Telescope. The optical test sources are used to establish the system alignment and provide test illumination to the Science Instrument suite. The Aft Optics Subsystem (AOS) Source Plate Assembly (ASPA) comprises sources, control electronics, cryogenic optical fiber and a precision mechanical structure. The system provides point source illumination from visible to mid infrared, narrow and broadband, and with an optical power range of 10 orders of magnitude. The precision metering structure holding the sources is mounted temporarily to the flight hardware to be removed after the system test campaign.

The James Webb Space Telescope (JWST) is the scientific successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 m² aperture (6 m class) telescope that will achieve diffraction limited angular resolution at a wavelength of 2 um. The science instrument payload includes four passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronography, as well as multi-object and integral-field spectroscopy over the 0.6 < λ < 5.0 um spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronography, and integral-field spectroscopy over the 5.0 < λ < 29 um spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations to be proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete. Construction, integration and verification testing is underway in all areas of the program. The JWST is on schedule for launch during 2018.

The Near-Infrared Spectrograph (NIRSpec) is one of the four instruments on the James Webb Space Telescope (JWST), scheduled for launch in 2018. NIRSpec has been designed and built by the European Space Agency (ESA) with Airbus Defense and Space Germany as prime contractor. The instrument covers the wavelength range from 0.6 to 5.3 micron and will be able to obtain spectra of more than 100 astronomical objects simultaneously by means of a configurable array of micro-shutters. It also features an integral field unit and a suite of slits for high contrast spectroscopy of individual objects. The extensive ground calibration campaign of NIRSpec was completed in Summer 2013, after which it was delivered to NASA for integration into the Integrated Science Instrument Module (ISIM). We highlight the major results from the instrument level calibration campaign which demonstrated full compliance with all opto-mechanical performance requirements. In addition, we present the current status of the instrument, describe the ongoing preparations for the Integrated Science Instrument Module (ISIM) test campaign to begin in June 2014, and briefly discuss plans for the pending exchange of the detector and micro-shutter assemblies following the first ISIM test cycle.

The James Webb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a tabletop workbench to study aspects of wavefront sensing and control for a segmented space telescope, including both commissioning and maintenance activities. JOST is complementary to existing optomechanical testbeds for JWST (e.g. the Ball Aerospace Testbed Telescope, TBT) given its compact scale and flexibility, ease of use, and colocation at the JWST Science & Operations Center. We have developed an optical design that reproduces the physics of JWST's three-mirror anastigmat using three aspheric lenses; it provides similar image quality as JWST (80% Strehl ratio) over a field equivalent to a NIRCam module, but at HeNe wavelength. A segmented deformable mirror stands in for the segmented primary mirror and allows control of the 18 segments in piston, tip, and tilt, while the secondary can be controlled in tip, tilt and x, y, z position. This will be sufficient to model many commissioning activities, to investigate field dependence and multiple field point sensing & control, to evaluate alternate sensing algorithms, and develop contingency plans. Testbed data will also be usable for cross-checking of the WFS&C Software Subsystem, and for staff training and development during JWST's five- to ten-year mission.

Recent publications resulting from observations conducted with the Hubble Space Telescope (HST) have highlighted the diagnostic power of near-infrared spectroscopy for the study of the atmospheric properties of transiting exoplanets. In this context, the James Webb Space Telescope (JWST) and it suite of instruments will have an unprecedented combination of sensitivity and spectral coverage. In this article, we focus on one of these instruments, the near-infrared spectrograph NIRSpec. NIRSpec will offer an aperture spectroscopy mode dedicated to the characterization of transiting exoplanets. It will cover the 0.6-5.3 μm spectral domain with 3 ranges of spectral resolution (R 100, 1000 and 2700). The predicted noise floor (photon noise and detector noise only, no systematics included) is lower than 100 ppm for a single 1-hour in-transit observation of an 7^th magnitude star, indicating that transit spectroscopy programs with NIRSpec will routinely have photon-noise limited noise floors of a few tens of ppm. In terms of brightness limits, at high spectral resolution, NIRSpec will be able to observe planets transiting stars with J-band magnitudes up to 6.5 in the worst case and 4.5 in the best case.

James Webb Space Telescope Optical Telescope Element (OTE) is a three mirror anastigmat consisting of a 6.5 m primary mirror (PM), a secondary mirror (SM) and a tertiary mirror. The primary mirror is made out of 18 segments. The telescope and instruments will be assembled at Goddard Space Flight Center (GSFC) to build the Optical Telescope Element-Integrated Science Instrument Module (OTIS). The OTIS will go through environmental testing at GSFC before being transported to Johnson Space Center for testing at cryogenic temperature. The objective of the primary mirror Center of Curvature test (CoC) is to characterize the PM before and after the environmental testing for workmanship. This paper discusses the CoC test including both a surface figure test and a new method for characterizing the state of the primary mirror using high speed dynamics interferometry.

A JWST OTE Pathfinder telescope that includes two spare primary mirror segments, a spare secondary mirror, and a large composite structure with a deployed secondary support structure is in the assembly stage and will be fully completed this year. This Pathfinder will check out key steps in the ambient mirror integration process and also be used at the Johnson Space Center (JSC) to check out the optical Ground Support Equipment (GSE) and associated procedures that will be used to test the full JWST telescope and instruments at JSC. This paper will summarize the Pathfinder integration and testing flow, the critical Ground Support Equipment it will test and the key tests planned with the Pathfinder.

After integration of the Optical Telescope Element (OTE) to the Integrated Science Instrument Module (ISIM) to become the OTIS, the JWST optics are tested at NASA’s Johnson Space Center (JSC) in the cryogenic vacuum Chamber A for alignment and optical performance. Tens of trucks full of custom test equipment are being delivered to the JSC, in addition to the large pieces built at the Center, and the renovation of the chamber itself. The facility is tested for the thermal stability control for optical measurements and contamination control during temperature transitions. The support for the OTIS is also tested for thermal stability control, load tested in the cryogenic environment, and tested for isolation of the background vibration for the optical measurements. The Center of Curvature Optical Assembly (COCOA) is tested for the phasing and wavefront error (WFE) measurement of an 18 segment mirror and for cryogenic operation. A photogrammetry system is tested for metrology performance and cryogenic operation. Test mirrors for auto-collimation measurements are tested for optical performance and cryogenic operation. An assembly of optical test sources are calibrated and tested in a cryogenic environment. A Pathfinder telescope is used as a surrogate telescope for cryogenic testing of the OTIS optical test configuration. A Beam Image Analyzer (BIA) is used as a surrogate ISIM with the Pathfinder in this test. After briefly describing the OTIS optical test configuration, the paper will overview the list and configuration of significant tests of the equipment leading up to the OTIS test.

In June 2012, Euclid, ESA's Cosmology mission was approved for implementation. Afterwards the industrial contracts were signed for the payload module and the spacecraft prime, and the mission requirements consolidated. We present the status of the mission in the light of the design solutions adopted by the contractors. The performances of the spacecraft in its operation, the telescope assembly, the scientific instruments as well as the data-processing have been carefully budgeted to meet the demanding scientific requirements. We give an overview of the system and where necessary the key items for the interfaces between the subsystems.

Euclid is an European Space Agency (ESA) mission to map the geometry of the dark Universe. The mission will investigate the distance-redshift relationship and the evolution of cosmic structures. It will achieve this by measuring shapes and redshifts of galaxies and clusters of galaxies out to redshifts ~2, equivalent to 10 billion years back in time. Euclid will make use of two primary cosmological probes, in a wide survey over the full extragalactic sky : the Weak Gravitational Lensing (WL) and Baryon Acoustic Oscillations (BAO). The main goal of the Euclid payload module (PLM) is to provide high quality imaging of galaxies and accurate measurement (less than 0.1%) of galaxies redshift over a large field of view (FoV). The present paper focuses on the telescope of the PLM excluding the instruments. We present a brief introduction to the Euclid PLM system and will report how the constraints of each instrument have driven the definition of the telescope-to-instrument optical interfaces. Furthermore we introduce the description of the telescope optical characteristics and report its nominal performances. Finally, the technical challenges to be faced by ESA’s industrial partners are underlined.

Euclid-VIS is the large format visible imager for the ESA Euclid space mission in their Cosmic Vision program, scheduled for launch in 2020. Together with the near infrared imaging within the NISP instrument, it forms the basis of the weak lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-900 nm over a field of view of ~0.5 deg². By combining 4 exposures with a total of 2260 sec, VIS will reach to V=24.5 (10σ) for sources with extent ~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable point spread function (PSF) over a wide survey area of 15000 deg² to measure the cosmic shear from nearly 1.5 billion galaxies to high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also provide a legacy dataset with an unprecedented combination of spatial resolution, depth and area covering most of the extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Consortium during the period up to the Preliminary Design Review.

The Euclid mission objective is to understand why the expansion of the Universe is accelerating by mapping the geometry of the dark Universe by investigating the distance-redshift relationship and tracing the evolution of cosmic structures. The Euclid project is part of ESA's Cosmic Vision program with its launch planned for 2020. The NISP (Near Infrared Spectro-Photometer) is one of the two Euclid instruments and is operating in the near-IR spectral region (0.9-2μm) as a photometer and spectrometer. The instrument is composed of: - a cold (135K) optomechanical subsystem consisting of a SiC structure, an optical assembly (corrector and camera lens), a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control system - a detection subsystem based on a mosaic of 16 Teledyne HAWAII2RG cooled to 95K with their front-end readout electronic cooled to 140K, integrated on a mechanical focal plane structure made with Molybdenum and Aluminum. The detection subsystem is mounted on the optomechanical subsystem structure - a warm electronic subsystem (280K) composed of a data processing / detector control unit and of an instrument control unit that interfaces with the spacecraft via a 1553 bus for command and control and via Spacewire links for science data This presentation describes the architecture of the instrument at the end of the phase B (Preliminary Design Review), the expected performance, the technological key challenges and preliminary test results obtained on a detection system demonstration model.

The James Webb Space Telescope (JWST) is a large aperture, infrared telescope planned for launch in 2018. JWST is a facility observatory that will address a broad range of science goals covering four major themes: First light and Re- Ionization, the Assembly of Galaxies, the Birth of Stars and Protoplanetary Systems, and Planetary Systems and the Origins of Life. JWST embodies several major technical challenges. With a 6.5 meter diameter mirror it will be the largest space telescope ever flown. It is the first cryogenic telescope to incorporate passive cooling, achieved by means of a large sunshade, to reach its ~40 K operating temperature. Due to the size of the Observatory, it must be stowed for launch, and then deployed to its operational configuration on its way to an orbit around the second Lagrange point. JWST is well on its way from drawing board to sky. Much of the flight hardware is already built and tested at the sub-system level. In this talk we will focus on the remaining tasks on the road to JWST’s first science observations on the sky. Prior to the launch, the remaining work to integrate the observatory elements centers around four major activities: • Cryo-optical testing of the instrument complement • Cryo-optical testing of the assembled telescope and instrument complement; • Integration of the observatory • Full-scale testing of the observatory deployments. We will discuss the design and philosophy underlying the cryo-optical test program for the Observatory. Cryo-optical testing begins with the instrument complement at the Goddard Space Flight Center, and finishes with an end-to-end test of the assembled telescope in the world’s largest cryogenic vacuum chamber at the Johnson Space Flight Center. In the context of a detailed overview of JWST’s deployment steps after launch, we will describe the final stages of Observatory integration and the testing to verify these deployments, ready for launch. Finally, we will discuss the post-launch timeline to transition the stowed Observatory to the start of science operations.

The Square Kilometre Array is the next-generation radio-telescope. It will be a true mega-science facility. It is being designed and will be built by a global consortium, headquartered in the UK. The consortium currently has 11 member countries but is open for additional members at any time. The SKA Observatory will have sites in Australia and South Africa, and will build on the two precursor telescopes, ASKAP and MeerKAT, currently under construction on the sites. The SKA is being designed as a physics machine for the 21st Century and will address scientific questions such as the nature of gravity, the origins of the Universe and the origins of life. I will describe the scientific rationale for the SKA; the technologies selected to deliver that science and the challenges posed in handling the massive data volumes to be generated by the observatory. The SKA is now in the detailed design phase. Funding exceeding €120M has been committed by the partner nations to deliver that design. The design will be complete at the end of 2016 and, assuming construction funding is secured, the procurement process will begin in 2017 and construction in early 2018. The SKA will deliver early science by 2020.

We describe the algorithms and results of an estimation of the science yield for five candidate coronagraph designs for the WFIRST-AFTA space mission. The targets considered are of three types, known radial-velocity planets, expected but as yet undiscovered exoplanets, and debris disks, all around nearby stars. The results of the original estimation are given, as well as those from subsequently updated designs that take advantage of experience from the initial estimates.

The WFIRST-AFTA coronagraph will directly image exoplanets and disks around nearby stars, and obtain spectra. The coronagraph has photometric bands covering about 400-1000 nm, and an integral field spectrometer with a resolution of about 70. The range of sensitivity in angular separation from a star is about 0.1 to 0.6 arc-seconds. The limiting contrast is about 10^-9, and a goal of 10^-10. The engineering development program is focused on low-order wavefront sensing and control, coronagraph masks, coronagraph performance, speckle detection and suppression, post-processing algorithms, an integral field spectrometer, and low-noise detectors. Progress and plans in these areas will be reviewed.

NASA’s WFIRST-AFTA mission concept includes the first high-contrast stellar coronagraph in space. This coronagraph will be capable of directly imaging and spectrally characterizing giant exoplanets similar to Neptune and Jupiter, and possibly even super-Earths, around nearby stars. In this paper we present the plan for maturing coronagraph technology to TRL5 in 2014-2016, and the results achieved in the first 6 months of the technology development work. The specific areas that are discussed include coronagraph testbed demonstrations in static and simulated dynamic environment, design and fabrication of occulting masks and apodizers used for starlight suppression, low-order wavefront sensing and control subsystem, deformable mirrors, ultra-low-noise spectrograph detector, and data post-processing.

The coronagraph instrument in the WFIRST-AFTA mission will allow high contrast imaging of exoplanetary systems with the benefit of a 2.4 meter space telescope. The instrument will feature an integral field spectrograph (IFS) capable of measuring spectra from exoplanets. Since the typical exoplanet target will be dimmer than the host star by a factor of ~1e9, and the dispersion of this light into many spectral channels further suppresses the photon rate, the noise requirements on the detector for this instrument will be very tight. From a performance perspective, many parameters are important, including the read noise, the dark current, and the clock induced charge. At the same time, from a functionality perspective, the unique challenges of the space environment, in particular damage from high energy cosmic rays, need to be assessed and mitigated. In this paper we present our recent work in selecting the detector for the WFIRST-AFTA IFS. We also discuss flight operation considerations and risks associated with these detectors as well as their technology readiness level.

The most recent concept for the Wide Field Infrared Survey Telescope (WFIRST) flight mission features a secondary, descopable, instrument that will perform exoplanet detection via coronagraphy of the host star. This observatory is based on the existing Astrophysics Focused Telescope Assets (AFTA) 2.4-meter telescope. The mission will study exoplanets via coronagraphy and gravitational microlensing, probe dark energy, and survey the near infrared sky. Over the past year, the engineering team has been working with the science definition team to refine the mission and payload concepts. We present the current design of the coronagraph instrument point design.

The Astrophysics Focused Telescope Assets (AFTA) is one of a pair of space-qualified 2.4 meter diameter telescopes given to NASA. One plan is to use the telescope for WFIRST with a coronagraph as a secondary instrument for high contrast imaging of exoplanets and disks. Because the system is obscured by a secondary mirror and spiders, it is not the optimal unobscured configuration to which most of current proposed space coronagraphs have been designed. In the later half of 2013 a study was undertaken to evaluate coronagraphs designed specifically for the AFTA telescope. As part of this process, end-to-end numerical modeling was performed with a realistically aberrated system to determine the contrast limits of each technique. Reported here are the simulation procedures and a summary of results for four coronagraphs (hybrid Lyot, shaped pupil, vector vortex, and PIAA complex mask) evaluated for the technology downselect.

We evaluate the broadband contrast performance of a Phase Induced Amplitude Apodization (PIAA) coronagraph configuration through modeling and simulations. Broadband occulter mask design for PIAA-CMC is at an early stage, and a study of the effects of wavefront control on broadband contrast is needed to determine the level of control the occulting mask must achieve, so that the combination of occulter and wavefront control optimization meets contrast targets. The basic optical design of the PIAA coronagraph is the same as NASA’s High Contrast Imaging Testbed (HCIT) setup at the Jet Propulsion Laboratory (JPL). Using two deformable mirrors and a broadband wavefront sensing and control algorithm, we create a “dark hole” in the broadband point-spread function (PSF) with an inner working angle (IWA) of 2(fλ/D)_sky. We evaluate a system using PIAA mirrors to create an apodization but not having any wavefront error at its exit-pupil, and having an obscured pupil and a new, 20-ring PIAACMC occulting mask. We also investigate the effect of Lyot stops of various sizes. For the configuration simulated here with the second-generation PIAA mirrors and early mask designs (which were not yet fully optimized), the best 10% broadband contrast value was ~6.1×10^-8. This is a 2x improvement beyond what the coronagraph produces in the absence of wavefront control, which implies that further improvement must come from architecture changes or further mask optimization improvements.

The Gaia payload ensures maximum passive stability using a single material, SiC, for most of its elements. Dedicated metrology instruments are, however, required to carry out two functions: monitoring the basic angle and refocusing the telescope. Two interferometers fed by the same laser are used to measure the basic angle changes at the level of μas (prad, micropixel), which is the highest level ever achieved in space. Two Shack- Hartmann wavefront sensors, combined with an ad-hoc analysis of the scientific data are used to define and reach the overall best-focus. In this contribution, the systems, data analysis, procedures and performance achieved during commissioning are presented .

The ESA Gaia space astrometry mission will perform an all-sky survey of stellar objects complete in the nominal magnitude range G = [6.0 - 20.0]. The stars with G < 6.0, i.e. those visible to the unaided human eye, would thus not be observed by Gaia. We present an algorithm configuration for the Gaia on-board autonomous object observation system that makes it possible to observe very bright stars with G = [2.0-6.0). Its performance has been tested during the in-orbit commissioning phase achieving an observation completeness of ~ 94% at G = 3 – 5.7 and ~ 75% at G = 2 – 3. Furthermore, two targeted observation techniques for data acquisition of stars brighter than G=2.0 were tested. The capabilities of these two techniques and the results of the in-flight tests are presented. Although the astrometric performance for stars with G < 6.0 has yet to be established, it is clear that several science cases will benefit from the results of the work presented here.

Small-JASMINE program (Japan Astrometry Satellite Mission for INfrared Exploration) is one of applicants for JAXA (Japan Aerospace Exploration Agency) space science missions launched by Epsilon Launch Vehicles, and now being reviewed in the Science Committee of ISAS (Institute of Space and Astronautical Science), JAXA. Telescope of 300 mm aperture diameter will focus to the central region of the Milky Way Galactic. The target of Small-JASMINE is to obtain reliable measurements of extremely small stellar motions with the highest accuracy of 10 μ arcseconds and to provide precise distances and velocities of multitudes of stars up to 30,000 light years. Preliminary Structure design of Small- JASMINE has been done and indicates to satisfy all of requirements from the mission requirement, the system requirement, Epsilon Launch conditions and interfaces of the small science satellite standard bus. High margin of weight for the mission allows using all super invar structure that may reduce unforeseen thermal distortion risk especially caused by connection of different materials. Thermal stability of the telescope is a key issue and should be verified in a real model at early stage of the development.

Gaia is a European Space Agency cornerstone mission launched 19 December 2013 from French Guyana. Gaia will map the sky down to the 20th magnitude for point sources. Astrometry and photometry is done for all detected objects and spectroscopy down to magnitude limit 16. At the moment of writing this abstract Gaia is being commissioned. All subsystems have been successfully operated. Gaia is in its operational orbit around L2 point. The attitude control with use of the stars from the science instrument has been successfully executed. The alignment of optical elements is ongoing with an iterative process involving focusing and spin speed adjustments as well. The Focal Plane Assembly is fully functional with all 106 CCDs operational and the Phased Array Antenna can transmit all science data down. The commissioning phase is anticipated to last till May 2014. The nominal operations are scheduled for 5 years. The scientific yield is expected to contain a billion stars with positions, distances and proper motions based on astrometry. With photometry the stellar properties of this sample can be deduced. Finally from the spectroscopy Gaia allows extraction of some 150 million radial velocities for the brightest stars. This information will allow addressing the main scientific goals of Gaia concerning the structure, history and evolution of our Milky Way Galaxy. In addition to Galactic structure, Gaia will allow addressing various other science areas. For stellar astrophysics Gaia will provide the long awaited distances and census of multiple star systems. Gaia is expected to discover few thousand exo-planets. The main belt asteroid orbits will be improved significantly. Eventually even fundamental physics can be done with tests on general relativity. The presentation will summarize the status of the spacecraft and provide updated scientific performance estimates based on the in-orbit data from the commissioning phase.

The Atacama Large Millimeter/submillimeter Array is transitioning from construction to operations. This connected element array currently operates from wavelengths of 3-mm to 350-microns with up to 66 array elements, 54 of 12-m diameter and 12 of 7-m diameter. While the antennas and most of the hardware for the receivers are on site, array capabilities are still expanding rapidly. In parallel with construction activities, early science observations have been going on since October 2011. At the time of the meeting, ALMA will be starting the third cycle of observing with many exciting, fundamental results already obtained. We will present the current status of the project and give an overview of the trailblazing science results obtained so far. The potential of the fully operational ALMA will be outlined as well as some of the development projects that are considered. In summary, this talk will address the past, present and future of ALMA, describe the transformational science that is and will be produced with ALMA.

This paper considers requirements for a future large space telescope to follow the James Webb Space Telescope, starting in the next decade. Its ambitious science program includes direct imaging and spectroscopy of Earth-like planets orbiting other stars, resolving individual stars in nearby galaxies, and probing the most distant regions of the observable universe to a visible-light resolution of 100 parsec, while providing high spectral resolution for wavelengths from 100 to 2,500 nm. The top-level optical requirements flowdown is briefly described, with reference to existing and future capabilities. The intent is to identify technology development needed in the last half of this decade, to support the priorities of the 2020 Decadal Survey.

In 2009 the Astrophysics Division at NASA Headquarters established the Strategic Astrophysics Technology (SAT) solicitation as a new technology maturation program to fill the needed gap for mid-Technology Readiness Level (TRL) levels (3≤ TRL <6). In three full proposal selection cycles since the inception of this program, more than 40 investigations have been selected, many meritorious milestones have been met and advances have been achieved. In this paper, we review the process of establishing technology priorities, the management of technology advancements and milestones, and the incipient success of some of these investigations in light of the need of future space missions.

Space-based gravitational-wave observatories will systematically study the source-rich band of gravitational waves from 0.0001 Hz to 1 Hz. All current designs require propagation of a laser beam from one spacecraft to another over immense distances. An optical telescope is needed for efficient power delivery and its design is driven by the interferometric displacement sensitivity requirements. Here we describe the design for a catoptric telescope that meets those requirements, emphasizing differences from the usual specifications for high quality image formation, and discuss design trade-offs as well as early results from research into scattered light suppression and modeling that may enable alternative designs.

Pursuing ground breaking science in a highly cost-constrained environment presents new challenges to the development of future space astrophysics missions. Within the conventional cost models for large observatories, executing a flagship “mission after next” appears to be unstainable. To achieve our nation’s science ambitions requires a new paradigm of system design, development and manufacture. This paper explores the nature of the current paradigm and proposes a series of steps to guide the entire community to a sustainable future.

The ATLAST 9.2m architecture has evolved to be more cost effective while also meeting a more thorough understanding of the driving science requirements. The new approach can fit in an existing Delta IV Heavy rocket and makes extensive use of heritage and selective use of technology in order to minimize development time and cost. We have performed a more thorough look at how to meet the stability requirements for both thermal and dynamics and have an approach consistent with an initial error budget. In addition, we have developed concepts to support robotic or human servicing in a cost effective manner through a modular approach that relies on simple, external access and metrology. These refinements to the architecture enable a cost-effective, long-lifecycle, and relatively low risk approach to development.

We describe how availability of new solar electric propulsion (SEP) technology can substantially increase the science capability of space astronomy missions working within the near-UV to far-infrared (UVOIR) spectrum by making dark sky orbits accessible for the first time. We present two case studies in which SEP is used to enable a 700 kg Explorer-class and 7000 kg flagship-class observatory payload to reach an orbit beyond where the zodiacal dust limits observatory sensitivity. The resulting scientific performance advantage relative to a Sun-Earth L2 point (SEL2) orbit is presented and discussed. We find that making SEP available to astrophysics Explorers can enable this small payload program to rival the science performance of much larger long development-time systems. Similarly, we find that astrophysics utilization of high power SEP being developed for the Asteroid Redirect Robotics Mission (ARRM) can have a substantial impact on the sensitivity performance of heavier flagship-class astrophysics payloads such as the UVOIR successor to the James Webb Space Telescope.

High resolution imaging from space requires very large apertures, such as NASA’s current mission the James Webb Space Telescope (JWST) which uses a deployable 6.5m segmented primary. Future missions requiring even larger apertures (>>10m) will present a great challenge relative to the size, weight and power constraints of launch vehicles as well as the cost and schedule required to fabricate the full aperture. Alternatively, a highly obscured annular primary can be considered. For example, a 93.3% obscured 30m aperture having the same total mirror area (91m²) as a 10.7m unobscured telescope, can achieve ~3X higher limiting resolution performance. Substantial cost and schedule savings can be realized with this approach compared to fully filled apertures of equivalent resolution. A conceptual design for a ring-shaped 30m telescope is presented and the engineering challenges of its various subsystems analyzed. The optical design consists of a 20X annular Mersenne form beam compactor feeding a classical 1.5m TMA telescope. Ray trace analysis indicates the design can achieve near diffraction limited images over a 200μrad FOV. The primary mirror consists of 70 identical rectangular 1.34x1.0m segments with a prescription well within the demonstrated capabilities of the replicated nanolaminate on SiC substrate technology developed by AOA Xinetics. A concept is presented for the deployable structure that supports the primary mirror segments. A wavefront control architecture consisting of an optical metrology subsystem for coarse alignment and an image based fine alignment and phasing subsystem is presented. The metrology subsystem is image based, using the background starfields for distortion and pointing calibration and fiducials on the segments for measurement. The fine wavefront control employs a hill climbing algorithm operating on images from the science camera. The final key technology required is the image restoration algorithm that will compensate for the highly obscured aperture. The results of numerical simulations of this algorithm will be presented and the signal-tonoise requirements for its successful application discussed. It is shown that the fabrication of the 30m telescope and all its supporting subsystems are within the scope of currently demonstrated technologies. It is also shown that the observatory can be brought to geosynchronous orbit, in its entirety, with a standard launch vehicle.

Astronomical flagship missions after JWST will require affordable space telescopes and science instruments. Innovative spacecraft-electro-opto-mechanical system architectures matched to the science requirements are needed for observations for exoplanet characterization, cosmology, dark energy, galactic evolution formation of stars and planets, and many other research areas. The needs and requirements to perform this science will continue to drive us toward larger and larger apertures. Recent technology developments in precision station keeping of spacecraft, interplanetary transfer orbits, wavefront/sensing and control, laser engineering, macroscopic application of nano-technology, lossless optical designs, deployed structures, thermal management, interferometry, detectors and signal processing enable innovative telescope/system architectures with break-through performance. Unfortunately, NASA’s budget for Astrophysics is unlikely to be able to support the funding required for the 8 m to 16 m telescopes that have been studied as a follow-on to JWST using similar development/assembly approaches without decimating the rest of the Astrophysics Division’s budget. Consequently, we have been examining the feasibility of developing an “Evolvable Space Telescope” that would begin as a 3 to 4 m telescope when placed on orbit and then periodically be augmented with additional mirror segments, structures, and newer instruments to evolve the telescope and achieve the performance of a 16 m or larger space telescope. This paper reviews the approach for such a mission and identifies and discusses candidate architectures.

TALC, Thin Aperture Light Collector is a 20 m space observatory project exploring some unconventional optical solutions (between the single dish and the interferometer) allowing the resolving power of a classical 27 m telescope. With TALC, the principle is to remove the central part of the prime mirror dish, cut the remaining ring into 24 sectors and store them on top of one-another. The aim of this far infrared telescope is to explore the 600 μm to 100 μm region. With this approach we have shown that we can store a ring-telescope of outer diameter 20m and ring thickness of 3m inside the fairing of Ariane 5 or Ariane 6. The general structure is the one of a bicycle wheel, whereas the inner sides of the segments are in compression to each other and play the rule of a rim. The segments are linked to each other using a pantograph scissor system that let the segments extend from a pile of dishes to a parabolic ring keeping high stiffness at all time during the deployment. The inner corners of the segments are linked to a central axis using spokes as in a bicycle wheel. The secondary mirror and the instrument box are built as a solid unit fixed at the extremity of the main axis. The tensegrity analysis of this structure shows a very high stiffness to mass ratio, resulting into 3 Hz Eigen frequency. The segments will consist of two composite skins and honeycomb CFRP structure build by replica process. Solid segments will be compared to deformable segments using the controlled shear of the rear surface. The adjustment of the length of the spikes and the relative position of the side of neighbor segments let control the phasing of the entire primary mirror. The telescope is cooled by natural radiation. It is protected from sun radiation by a large inflatable solar screen, loosely linked to the telescope. The orientation is performed by inertia-wheels. This telescope carries a wide field bolometer camera using cryocooler at 0.3K as one of the main instruments. This telescope may be launched with an Ariane 6 rocket up to 800 km altitude, and use a plasma stage to reach the Lagrange 2 point within 18 month. The plasma propulsion stage is a serial unit also used in commercial telecommunication satellites. When the plasma launch is completed, the solar panels will be used to provide the power for communication, orientation and power the cryo-coolers for the instruments. The guide-line for development of this telescope is to use similar techniques and serial subsystems developed for the satellite industry. This is the only way to design and manufacture a large telescope at a reasonable cost.

The future of far-infrared observations rests on our capacity to reach sub-arcsecond angular resolution around 100 μm, in order to achieve a significant advance with respect to our current capabilities. Furthermore, by reaching this angular resolution we can bridge the gap between capacities offered by the JWST in the near infrared and those allowed by ALMA in the submillimeter, and thus benefit from similar resolving capacities over the whole wavelength range where interstellar dust radiates and where key atomic and molecular transitions are found. In an accompanying paper,¹ we present a concept of a deployable annular telescope, named TALC for Thinned Aperture Light Collector, reaching 20m in diameter. Being annular, this telescope features a main beam width equivalent to that of a 27m telescope, i.e. an angular resolution of 0.92" at 100 μm. In this paper we focus on the science case of such a telescope as well on the aspects of unconventional data processing that come with this unconventional optical configuration. The principal science cases of TALC revolve around its imaging capacities, that allow resolving the Kuiper belt in extra-solar planetary systems, or the filamentary scale in star forming clouds all the way to the Galactic Center, or the Narrow Line Region in Active Galactic Nuclei of the Local Group, or breaking the confusion limit to resolve the Cosmic Infrared Background. Equipping this telescope with detectors capable of imaging polarimetry offers as well the extremely interesting perspective to study the influence of the magnetic field in structuring the interstellar medium. We will then present simulations of the optical performance of such a telescope. The main feature of an annular telescope is the small amount of energy contained in the main beam, around 30% for the studied configuration, and the presence of bright diffraction rings. Using simulated point spread functions for realistic broad-band filters, we study the observing performance of TALC in typical situations, i.e a field of point sources, and fields with emission power at every physical scales, taken to represent an extragalactic deep field observation and an interstellar medium observation. We investigate different inversion techniques to try and recover the information present in the input field. We show that techniques combining a forward modeling of the observation process and a reconstruction algorithm exploiting the concept of sparsity (i.e. related to the more general field of compressed sensing) represent a promising avenue to reach the angular resolution promised by the main beam of TALC.

The Primordial Inflation Explorer is an Explorer-class mission to measure the gravity-wave signature of primordial inflation through its distinctive imprint on the linear polarization of the cosmic microwave background. PIXIE uses an innovative optical design to achieve background-limited sensitivity in 400 spectral channels spanning 2.5 decades in frequency from 30 GHz to 6 THz (1 cm to 50 micron wavelength). Multi-moded non-imaging optics feed a polarizing Fourier Transform Spectrometer to produce a set of interference fringes, proportional to the difference spectrum between orthogonal linear polarizations from the two input beams. Multiple levels of symmetry and signal modulation combine to reduce the instrumental signature and confusion from unpolarized sources to negligible levels. PIXIE will map the full sky in Stokes I, Q, and U parameters with angular resolution 2.6 deg and sensitivity 0.2 µK per 1 deg square pixel. The principal science goal is the detection and characterization of linear polarization from an inflationary epoch in the early universe, with tensor-to-scalar ratio r < 10^-3 at 5 standard deviations. In addition, PIXIE will measure the absolute frequency spectrum to constrain physical processes ranging from inflation to the nature of the first stars to the physical conditions within the interstellar medium of the Galaxy. We describe the PIXIE instrument and mission architecture with an emphasis on the expected level of systematic error suppression.

We present the mission design of LiteBIRD, a next generation satellite for the study of B-mode polarization and inflation from cosmic microwave background radiation (CMB) detection. The science goal of LiteBIRD is to measure the CMB polarization with the sensitivity of δr = 0:001, and this allows testing the major single-field slow-roll inflation models experimentally. The LiteBIRD instrumental design is purely driven to achieve this goal. At the earlier stage of the mission design, several key instrumental specifications, e.g. observing band, optical system, scan strategy, and orbit, need to be defined in order to process the rest of the detailed design. We have gone through the feasibility studies for these items in order to understand the tradeoffs between the requirements from the science goal and the compatibilities with a satellite bus system. We describe the overview of LiteBIRD and discuss the tradeoffs among the choices of scientific instrumental specifications and strategies. The first round of feasibility studies will be completed by the end of year 2014 to be ready for the mission definition review and the target launch date is in early 2020s.

We demonstrate the use of existing observations from the CASSINI spacecraft to be used for studies of stellar targets. The stellar lightcurve produced as hard edges within the rings pass across the field of view produces a stellar occultation not unlike lunar occultations. These events are observed with an on-board spectrograph, providing coverage of the near infrared from 1 to 5 microns. Here we demonstrate how the technique can be used to make spatially resolved measurements of stellar structure and test these measurements against independently published angular sizes. We also show how this technique can be extended into mapping of complex circum­ stellar structure and identify molecular layers in the atmosphere of Omicron Ceti, an evolved star. Finally we demonstrate how several events can be combined tomographically to reconstruct high resolution images of stellar targets.

Canadian astronomers have participated in space astronomy since the first OAO missions in the 1960s and 1970s. Individual Canadian scientists have been members of HST instrument teams, and advisory groups for IUE and HEAO missions, as well as competing successfully for observing time on NASA, ESA, and Japanese astronomy satellites. With the formation of the Canadian Space Agency, Canada became partner in the FUSE mission, the ISRO Astrosat, and the JWST, providing hardware and science team membership. The Canadian Astronomy Data centre was one of the three original world-wide archive distribution centres for HST, and now is involved in many space and ground-based data services. The MOST observatory is an all- Canadian microsat that has operated for nearly a decade. Canada is currently involved in partnership in a number of imminent space facilities, as well as participating in teams defining future missions. I will describe this history, and review the technical and scientific capability that exist in Canada now. I will outline prospects for the future, including a concept for a high resolution orbiting telescope that will fill the gap in high resolution UV astronomy when HST operations cease.

We present the current status of SPICA (Space Infrared Telescope for Cosmology and Astrophysics), which is a mission optimized for mid- and far-infrared astronomy with a cryogenically cooled 3.2 m telescope. SPICA is expected to achieve high spatial resolution and unprecedented sensitivity in the mid- and far-infrared, which will enable us to address a number of key problems in present-day astronomy, ranging from the star-formation history of the universe to the formation of planets. We have carried out the “Risk Mitigation Phase” activity, in which key technologies essential to the realization of the mission have been extensively developed. Consequently, technical risks for the success of the mission have been significantly mitigated. Along with these technical activities, the international collaboration framework of SPICA had been revisited, which resulted in maintenance of SPICA as a JAXA-led mission as in the original plan but with larger contribution of ESA than that in the original plan. To enable the ESA participation, a SPICA proposal to ESA is under consideration as a medium-class mission under the framework of the ESA Cosmic Vision. The target launch year of SPICA under the new framework is FY2025.

The Japanese SPace Infrared telescope for Cosmology and Astrophysics, SPICA, aims to provide astronomers with a truly new window on the universe. With a large -3 meter class- cold -6K- telescope, the mission provides a unique low background environment optimally suited for highly sensitive instruments limited only by the cosmic background itself. SAFARI, the SpicA FAR infrared Instrument SAFARI, is a Fourier Transform imaging spectrometer designed to fully exploit this extremely low far infrared background environment. The SAFARI consortium, comprised of European and Canadian institutes, has established an instrument reference design based on a Mach-Zehnder interferometer stage with outputs directed to three extremely sensitive Transition Edge Sensor arrays covering the 35 to 210 μm domain. The baseline instrument provides R > 1000 spectroscopic imaging capabilities over a 2’ by 2’ field of view. A number of modifications to the instrument to extend its capabilities are under investigation. With the reference design SAFARI’s sensitivity for many objects is limited not only by the detector NEP but also by the level of broad band background radiation – the zodiacal light for the shorter wavelengths and satellite baffle structures for the longer wavelengths. Options to reduce this background are dedicated masks or dispersive elements which can be inserted in the optics as required. The resulting increase in sensitivity can directly enhance the prime science goals of SAFARI; with the expected enhanced sensitivity astronomers would be in a better position to study thousands of galaxies out to redshift 3 and even many hundreds out to redshifts of 5 or 6. Possibilities to increase the wavelength resolution, at least for the shorter wavelength bands, are investigated as this would significantly enhance SAFARI’s capabilities to study star and planet formation in our own galaxy.

The infrared space telescope SPICA, Space Infrared Telescope for Cosmology and Astrophysics, is a next-generation astronomical project of the Japanese Aerospace Exploration Agency (JAXA), which features a 3m-class and 6K cryogenically- cooled space telescope. This paper outlines the current status for the preliminary structural design of the SPICA payload module. Dedicated studies were conducted for key technologies to enhance the design accuracy of the SPICA cryogenic assembly and mitigate the development risk. One of the results is described in this paper for the concept of the on-orbit truss separation mechanisms, which aim to both reduce the heat load from the main truss assembly and isolate the micro-vibration by changing the natural frequency of the spacecraft.

The Spitzer Space Telescope Infrared Array Camera (IRAC) is the only space-based instrument currently capable of continuous long duration monitoring of brown dwarfs to detect variability and characterize their atmospheres. Any such studies are limited, however, by the accuracy to which we know the positions and distances to these targets (most of which are newly discovered and therefore do not yet have multiple epochs of astrometric data). To that end, we have begun a new initiative to adapt the astrometric drift scanning technique employed by the Hubble Space Telescope to enhance Spitzer measurements of parallaxes and proper motions of brown dwarfs and other targets. A suite of images are taken with a set of sources scanned across the array. This technique reduces random noise by coaddition, and because each target covers multiple pixels we are able to average over residual instrumental distortion and intra-pixel variations. Although these benefits can be realized with appropriate dithering, scanning is much more effcient because we can take data concurrently with the spacecraft motion, covering many pixels without waiting to reposition and settle. In this contribution we demonstrate that the observing mode works and describe our software for analyzing the observations. We outline ongoing efforts towards simultaneously solving for source position and residual distortion. Initial testing shows a factor of more than 2 improvement in the astrometric precision can be obtained with Spitzer. We anticipate being able to measure parallaxes for sources out to about 50 pc, increasing the volume surveyed by a factor of 100 and enabling luminosity measurements of the young population of brown dwarfs in the β Pictoris moving group. This observing mode will be ready for public use around Winter of 2015.

Solar-C is a mission designed to answer some of the most important questions in solar physics. Recent progress from missions like Hinode has revealed that the different parts of the solar atmosphere are coupled in fundamental ways and has defined the spatial scales and temperature regimes that need to be observed in order to achieve a comprehensive physical understanding of this coupling. Solar-C will deploy a carefully coordinated suite of three complementary instruments: the Solar Ultra-violet Visible and IR Telescope (SUVIT), the high-throughput EUV Spectroscopic Telescope (EUVST), and an X-ray Imaging Telescope (XIT). The science of Solar-C will greatly advance our understanding of the Sun, of basic physical processes operating throughout the universe, and of how the Sun influences the Earth and other planets in our solar system.

A large aperture solar optical telescope and its instruments for the SOLAR-C mission are under study to provide the critical physical parameters in the lower solar atmosphere and to resolve the mechanism of magnetic dynamic events happening there and in the upper atmosphere as well. For the precise magnetic field measurements and high angular resolution in wide wavelength region, covering FOV of 3 arcmin x3 arcmin, an entrance aperture of 1.4 m Gregorian telescope is proposed. Filtergraphs are designed to realize high resolution imaging and pseudo 2D spectro-polarimetry in several magnetic sensitive lines of both photosphere and chromosphere. A full stokes polarimetry is carried out at three magnetic sensitive lines with a four-slit spectrograph of 2D image scanning mechanism. We present a progress in optical and structural design of SOLAR-C large aperture optical telescope and its observing instruments which fulfill science requirements.

The Whipple mission was a proposal submitted to the NASA Discovery AO in 2010 to study the solid bodies of the Kuiper Belt and Oort Cloud via a blind occultation survey. Though not accepted for flight, the proposal was awarded funding for technology development. Detecting a significant number of Trans Neptunian Objects (TNOs) via a blind occultation survey requires a low noise, wide field of view, multi object differential photometer. The light curve decrement is typically a few percent over timescales of tenths of seconds or seconds for Kuiper Belt and Oort cloud objects, respectively. To obtain a statistically interesting number of detections, this photometer needs to observe many thousands of stars over several years since the rate of occultation for a single star given the space density of the TNOs is low. The light curves from these stars must be monitored with a sensor with a temporal resolution of rv 25-50 ms and with a read noise of< 20 e- rms. Since these requirements are outside the capability of CCDs, the Whipple mission intends to use Teledyne H2RG HyViSI Silicon Hybrid CMOS detectors operating in "window" read mode. The full Whipple focal plane consists of a 3x3 array of these sensors, with each sensor comprised of 1024x 1024 36/μm pixels. Combined with the telescope optic, the Whipple focal plane provides a FOV of rv36 deg2 . In operation, each HyViSI detector, coupled to a Teledyne SIDECAR ASIC, monitors the flux from 650 stars at 40 Hz. The ASIC digitizes the data at the required cadence and an FPGA provides preliminary occultation event selection. The proposed 2010 Whipple mission utilized a spacecraft in a a "drift-away" orbit which signifi­ cantly limited the available telemetry data rate. Most of the light curve processing is required to be on-board the satellite so only candidate occultation events are telemetered to the ground. Occul­ tation light curves must be processed in real time on the satellite by an Field Programmable Gate Array (FPGA). A simple, real time band pass filter, called the Equivalent Width (EW) algorithm, has been instantiated in the FPGA. This EW filter selects for telemetry only those occultation event light curves that differed significantly from noise. As part of our technology development program, a key facet of the proposed Whipple focal plane was constructed and operated in our laboratory consisting of a single HyViSI H2RG sensor, a Teledyne SIDECAR ASIC, and a flight-like Virtex-5 FPGA. In order to fully demonstrate the capabilities of this photometer, we also made a occultation light-curve simulator. The entire system can generate simulated occultation light curves, project them onto an H2RG sensor, read out the sensor in windowing mode at 40 Hz, pass the data to an FPGA that continuously monitors the light curves and dumps candidate occultation events to our simulated Ground Support Equipment (GSE). In this paper, we summarize the technical capabilities of our system, present sample data, and discuss how this system will be used to support our proposal effort for the next Discovery round.

The accurate determination of the solar photospheric radius has been an important problem in astronomy for many centuries. From the measurements made by the PICARD spacecraft during the transit of Venus in 2012, we obtained a solar radius of 696,156±145 kilometres. This value is consistent with recent measurements carried out atmosphere. This observation leads us to propose a change of the canonical value obtained by Arthur Auwers in 1891. An accurate value for total solar irradiance (TSI) is crucial for the Sun-Earth connection, and represents another solar astrophysical fundamental parameter. Based on measurements collected from different space instruments over the past 35 years, the absolute value of the TSI, representative of a quiet Sun, has gradually decreased from 1,371W.m⁻² in 1978 to around 1,362W.m⁻² in 2013, mainly due to the radiometers calibration differences. Based on the PICARD data and in agreement with Total Irradiance Monitor measurements, we predicted the TSI input at the top of the Earth’s atmosphere at a distance of one astronomical unit (149,597,870 kilometres) from the Sun to be 1,362±2.4W.m⁻², which may be proposed as a reference value. To conclude, from the measurements made by the PICARD spacecraft, we obtained a solar photospheric equator-to-pole radius difference value of 5.9±0.5 kilometres. This value is consistent with measurements made by different space instruments, and can be given as a reference value.

The Advance Mirror Technology Development (AMTD) project is in Phase 2 of a multiyear effort, initiated in FY12, to mature by at least a half TRL step six critical technologies required to enable 4 meter or larger UVOIR space telescope primary mirror assemblies for both general astrophysics and ultra-high contrast observations of exoplanets. AMTD continues to achieve all of its goals and accomplished all of its milestones to date. We have done this by assembling an outstanding team from academia, industry, and government with extensive expertise in astrophysics and exoplanet characterization, and in the design/manufacture of monolithic and segmented space telescopes; by deriving engineering specifications for advanced normal-incidence mirror systems needed to make the required science measurements; and by defining and prioritizing the most important technical problems to be solved.

The Advance Mirror Technology Development (AMTD) project is in Phase 2 of a multiyear effort, initiated in FY12, to mature by at least a half TRL step six critical technologies required to enable 4 meter or larger UVOIR space telescope primary mirror assemblies for both general astrophysics and ultra-high contrast observations of exoplanets. AMTD uses a science-driven systems engineering approach. We mature technologies required to enable the highest priority science AND provide a high-performance low-cost low-risk system. To give the science community options, we are pursuing multiple technology paths. A key task is deriving engineering specifications for advanced normal-incidence monolithic and segmented mirror systems needed to enable both general astrophysics and ultra-high contrast observations of exoplanets missions as a function of potential launch vehicles and their mass and volume constraints. A key finding of this effort is that the science requires an 8 meter or larger aperture telescope.

The 2010 Decadal Survey stated that an advanced large-aperture ultraviolet, optical, near-infrared (UVOIR) telescope is required to enable the next generation of compelling astrophysics and exoplanet science; and, that present technology is not mature enough to affordably build and launch any potential UVOIR mission concept. Under Science and Technology funding, NASA’s Marshall Space Flight Center (MSFC) and Exelis have developed a more cost effective process to make 4m class or larger monolithic spaceflight UV quality, low areal density, thermally and dynamically stable primary mirrors. A proof of concept 0.43m mirror was completed at Exelis optically tested at 250K at MSFC which demonstrated the ability for imaging out to 2.5 microns. The parameters and test results of this concept mirror are shown. The next phase of the program includes a 1.5m subscale mirror that will be optically and dynamically tested. The scale-up process will be discussed and the technology development path to a 4m mirror system by 2018 will be outlined.

Extreme Lightweight ZERODUR® Mirrors (ELZM) have been developed expressly to provide architects of spaceborne missions a new, cost-effective, option for implementation of medium and large Optical Telescope Assemblies (OTAs, up to 4+ meters in diameter). ZERODUR® is a traditional material in space with over a 30 year heritage. We will discuss the attributes of the material and fabrication methods to aggressively reduce weight to an extent now routinely available. Recent and emerging independent measurements of material properties will confirm the utility of this approach for new generations of OTAs. Data on dimensional stability over a broad practical temperature range will be referenced, as will recent mechanical strength data. Other data confirming suitability for use in space will be referenced. We will discuss how this data can be used for the architecture of a ELZM based cost-effective spaceborne OTA.

The desire to field space-based telescopes with apertures in excess of 10 meter diameter is forcing the development of extreme lightweighted large optomechanical structures. Sparse apertures, shell optics, and membrane optics are a few of the approaches that have been investigated and demonstrated. Membrane optics in particular have been investigated for many years. The MOIRE approach in which the membrane is used as a transmissive diffractive optical element (DOE) offers a significant relaxation in the control requirements on the membrane surface figure, supports extreme lightweighting of the primary collecting optic, and provides a path for rapid low cost production of the primary optical elements. Successful development of a powered meter-scale transmissive membrane DOE was reported in 2012. This paper presents initial imaging results from integrating meter-scale transmissive DOEs into the primary element of a 5- meter diameter telescope architecture. The brassboard telescope successfully demonstrates the ability to collect polychromatic high resolution imagery over a representative object using the transmissive DOE technology. The telescope includes multiple segments of a 5-meter diameter telescope primary with an overall length of 27 meters. The object scene used for the demonstration represents a 1.5 km square complex ground scene. Imaging is accomplished in a standard laboratory environment using a 40 nm spectral bandwidth centered on 650 nm. Theoretical imaging quality for the tested configuration is NIIRS 2.8, with the demonstration achieving NIIRS 2.3 under laboratory seeing conditions. Design characteristics, hardware implementation, laboratory environmental impacts on imagery, image quality metrics, and ongoing developments will be presented.

The USAF Academy Department of Physics has built FalconSAT-7, a membrane solar telescope to be deployed from a 3U CubeSat in LEO. The primary optic is a 0.2m photon sieve - a diffractive element consisting of billions of tiny circular dimples etched into a Kapton sheet. The membrane, its support structure, secondary optics, two imaging cameras and associated control/recording electronics are all packaged within half the CubeSat volume. Once in space, the supporting pantograph structure is deployed, extending out and pulling the membrane flat under tension. The telescope will then be directed at the Sun to gather images at H-alpha for transmission to the ground. Due for launch in 2015, FalconSAT-7 will serve as a pathfinder for future surveillance missions consisting of a 0.3m aperture deployed from a 12U satellite. Such a telescope would be capable of providing sub-meter resolution of ground-based objects.

Hyper Suprime-Cam (HSC) is a next generation wide field optical imaging camera built for 8.2 m Subaru telescope. The field of view is 1.5 degree in diameter and the nearly 50 cm image circle was paved by 116 fully depleted CCDs (2k x 4k 15 micron square pixels). To realize a seeing limit imaging at Mauna Kea, the specification on the overall instrument PSF is set as 0.32 arc-second (FWHM). This is crucial for our primary scientific objectives: weak gravitational weak lensing survey to probe dark matter distribution. We started building the camera in 2006, had a first light in 2012 and now in the final phase of the commissioning. The delivered image quality is mostly seeing limit as designed and we once observed the seeing size of 0.43 arc-second (median value over the field of view) in Y-band with 300 seconds exposure. Our 300 nights observing proposal has been already accepted. The program starts in March 2014 and continues over 5 years.

The Transiting Exoplanet Survey Satellite (TESS ) will search for planets transiting bright and nearby stars. TESS has been selected by NASA for launch in 2017 as an Astrophysics Explorer mission. The spacecraft will be placed into a highly elliptical 13.7-day orbit around the Earth. During its two-year mission, TESS will employ four wide-field optical CCD cameras to monitor at least 200,000 main-sequence dwarf stars with I_C (approximately less than) 13 for temporary drops in brightness caused by planetary transits. Each star will be observed for an interval ranging from one month to one year, depending mainly on the star's ecliptic latitude. The longest observing intervals will be for stars near the ecliptic poles, which are the optimal locations for follow-up observations with the James Webb Space Telescope. Brightness measurements of preselected target stars will be recorded every 2 min, and full frame images will be recorded every 30 min. TESS stars will be 10-100 times brighter than those surveyed by the pioneering Kepler mission. This will make TESS planets easier to characterize with follow-up observations. TESS is expected to find more than a thousand planets smaller than Neptune, including dozens that are comparable in size to the Earth. Public data releases will occur every four months, inviting immediate community-wide efforts to study the new planets. The TESS legacy will be a catalog of the nearest and brightest stars hosting transiting planets, which will endure as highly favorable targets for detailed investigations.

We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential Deformable Mirrors to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and / or segment gaps. We solve the highly non-linear Monge-Ampere equation that is the fundamental equation describing the physics of phase induced amplitude modulation. We determine the optimum configuration for our two sequential Deformable Mirror system and show that high-throughput and high contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to JWST, ACAD can attain at least 10^-7 in contrast and an order of magnitude higher for future Extremely Large Telescopes, even when the pupil features a "missing segment" . Because the converging non-linear mappings resulting from our Deformable Mirror shapes damps near-field diffraction artifacts in the vicinity of the discontinuities this solution is particularly appealing in terms of spectral bandwidth. We present preliminary results that illustrate the performances of ACAD in the presence of diffraction for apertures for with secondary support structures of varying width and argue that the ultimate contrast achieved can by combining ACAD with modern wavefront control algorithms.

For the technology development of the mission EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer)—a 0.7 m telescope equipped with a Phase-Induced Amplitude Apodization Coronagraph (PIAA- C) and a 2000-element MEMS deformable mirror, capable of raw contrasts of 10⁻⁶ at 1.2 λ/D and 10⁻⁷ above 2 λ /D — we developed two test benches simulating its key components, one in air, the other in vacuum. To achieve this level of contrast, one of the main goals is to remove low-order aberrations, using a Low-Order WaveFront Sensor (LOWFS). We tested this key component, together with the coronagraph and the wavefront control, in air at NASA Ames Research Center and in vacuum at Lockheed Martin. The LOWFS, controlling tip/tilt modes in real time at 1 kHz, allowed us to reduce the disturbances in air to 10⁻³ λ/D rms, letting us achieve a contrast of 2.8×10⁻⁷ between 1.2 and 2 λ/D. Tests are currently being performed to achieve the same or a better level of correction in vacuum. With those results, and by comparing them to simulations, we are able to deduce its performances on different coronagraphs— different sizes of telescopes, inner working angles, contrasts, etc. — and therefore study its contribution beyond EXCEDE.

This paper is the third in the series on the technology development for the EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer) mission concept, which in 2011 was selected by NASA's Explorer program for technology development (Category III). EXCEDE is a 0.7m space telescope concept designed to achieve raw contrasts of 1e6 at an inner working angle of 1.2 l/D and 1e7 at 2 l/D and beyond. This will allow it to directly detect and spatially resolve low surface brightness circumstellar debris disks as well as image giant planets as close as in the habitable zones of their host stars. In addition to doing fundamental science on debris disks, EXCEDE will also serve as a technological and scientific precursor for any future exo-Earth imaging mission. EXCEDE uses a Starlight Suppression System (SSS) based on the PIAA coronagraph, enabling aggressive performance. Previously, we reported on the achievement of our first milestone (demonstration of EXCEDE IWA and contrast in monochromatic light) in air. In this presentation, we report on our continuing progress of developing the SSS for EXCEDE, and in particular (a) the reconfiguration of our system into a more flight-like layout, with an upstream deformable mirror and an inverse PIAA system, and (b) testing this system in a vacuum chamber, including IWA, contrast, and stability performance. Even though this technology development is primarily targeted towards EXCEDE, it is also germane to any exoplanet direct imaging space-based telescopes because of the many challenges common to different coronagraph architectures and mission requirements. This work was supported in part by the NASA Explorer program and Ames Research Center, University of Arizona, and Lockheed Martin SSC.

Direct imaging is in general necessary to characterize exoplanets and disks. A coronagraph is an instrument used to create a dim (high-contrast) region in a star’s PSF where faint companions can be detected. All coronagraphic high-contrast imaging systems use one or more deformable mirrors (DMs) to correct quasi-static aberrations and recover contrast in the focal plane. Simulations show that existing wavefront control algorithms can correct for diffracted starlight in just a few iterations, but in practice tens or hundreds of control iterations are needed to achieve high contrast. The discrepancy largely arises from the fact that simulations have perfect knowledge of the wavefront and DM actuation. Thus, wavefront correction algorithms are currently limited by the quality and speed of wavefront estimates. Exposures in space will take orders of magnitude more time than any calculations, so a nonlinear estimation method that needs fewer images but more computational time would be advantageous. In addition, current wavefront correction routines seek only to reduce diffracted starlight. Here we present nonlinear estimation algorithms that include optimal estimation of sources incoherent with a star such as exoplanets and debris disks.

Several years ago at Princeton we invented a technique to optimize shaped pupil (SP) coronagraphs for any telescope aperture. In the last year, our colleagues at the Jet Propulsion Laboratory (JPL) invented a method to produce these non-freestanding mask designs on a substrate. These two advances allowed us to design SPs for two possible space telescopes for the direct imaging of exoplanets and disks, WFIRST-AFTA and Exo-C. In December 2013, the SP was selected along with the hybrid Lyot coronagraph for placement in the AFTA coronagraph instrument. Here we describe our designs and analysis of the SPs being manufactured and tested in the High Contrast Imaging Testbed at JPL.We also explore hybrid SP coronagraph designs for AFTA that would improve performance with minimal or no changes to the optical layout. These possibilities include utilizing a Lyot stop after the focal plane mask or applying large, static deformations to the deformable mirrors (nominally for wavefront correction) already in the system.

Imaging planets requires instruments capable of dealing with extreme contrast ratios and that have a high resolution. Coronagraphs that can reach a contrast ratio in a neighborhood of 10⁹ will be capable of observing Jupiter-like planets, while those with a contrast greater than a benchmark number of 10¹⁰ to within a few λ/D of an on-axis star will render possible imaging of Earth-like planets. Plans for achieving this feat have been developed for use on telescopes with unobscured, circularly symmetric apertures. However; given that the next generation of large telescopes are on-axis designs with support structures in the telescope aperture and a central obstruction due to the secondary mirror, it has proven necessary to develop coronagraphic techniques that compensate for obstructions. Pueyo and Norman (2012) present a possible solution to the problem of the support structures using ACAD. In this paper, we present a coronagraphic design that uses a vector vortex and pupil apodization to compensate for the secondary mirror that could possibly be used in conjunction with a wavefront control system and/or ACAD. This coronagraph is capable of achieving a contrast ratio of at least 10¹⁰ in a working angle of (1:5 - 30) λ/D in conjunction with an on-axis telescope. We can construct our pupil using a classical transmissive apodizer or pupil remapping. We find that the mirror shapes required are relatively simple (requiring ≤ 40 degrees of freedom to describe) and we expect they will be feasible to manufacture, and potentially even to implement with deformable mirrors. By combining existing high-contrast imaging techniques, we demonstrate that a relatively simple design may be used to image exo-Earths.

We present a new high-contrast imaging testbed designed to provide complete solutions in wavefront sensing, control and starlight suppression with complex aperture telescopes. The testbed was designed to enable a wide range of studies of the effects of such telescope geometries, with primary mirror segmentation, central obstruction, and spiders. The associated diffraction features in the point spread function make high-contrast imaging more challenging. In particular the testbed will be compatible with both AFTA-like and ATLAST-like aperture shapes, respectively on-axis monolithic, and on-axis segmented telescopes. The testbed optical design was developed using a novel approach to define the layout and surface error requirements to minimize amplitude­ induced errors at the target contrast level performance. In this communication we compare the as-built surface errors for each optic to their specifications based on end-to-end Fresnel modelling of the testbed. We also report on the testbed optical and optomechanical alignment performance, coronagraph design and manufacturing, and preliminary first light results.

Wide Field Camera 3 (WFC3) is the most used instrument on board the Hubble Space Telescope. Providing a broad range of high quality imaging capabilities from 200 to 1700mn using Silicon CCD and HgCdTe IR detectors, WFC3 is fulfilling both our expectations and its formal requirements. With the re-establishment of the observatory level "spatial scan" capability, we have extended the scientific potential ofWFC3 in multiple directions. These controlled scans, often in combination with low resolution slit-less spectroscopy, enable extremely high precision differential photometric measurements of transiting exo-planets and direct measurement of sources considerably brighter than originally anticipated. In addition, long scans permit the measurement of the separation of star images to accuracies approaching 25 micro-arc seconds (a factor of 10 better than prior FGS or imaging measurements) enables direct parallax observations out to 4 kilo-parsecs. In addition, we have employed this spatial scan capability to both assess and improve the mid­ spatial frequency flat field calibrations. WFC3 uses a Teledyne HgCdTe 1014xl014 pixel Hawaii-lR infrared detector array developed for this mission. One aspect of this detector with implications for many types of science observations is the localized trapping of charge. This manifests itself as both image persistence lasting several hours and as an apparent response variation with photon arrival rate over a large dynamic range. Beyond a generally adopted observing strategy of obtaining multiple observations with small spatial offsets, we have developed a multi-parameter model that accounts for source flux, accumulated signal level, and decay time to predict image persistence at the pixel level. Using a running window through the entirety of the acquired data, we now provide observers with predictions for each individual exposure within several days of its acquisition. Ongoing characterization of the sources on infrared background and the causes of its temporal and spatial variation has led to the appreciation of the impact of He I 1.083 micron emission from the earth's atmosphere. This adds a significant and variable background to the two filters and two grisms which include this spectral feature when the HST spacecraft is outside of the earth's shadow. After nearly five years in orbit, long term trending of the scientific and engineering behavior of WFC3 demonstrates excellent stability other than the expected decline in CCD charge transfer efficiency. Addition of post-flash signal to images is shown to markedly improve the transfer efficiency for low level signals. Combined with a pixel based correction algorithm developed at STScl, CCD performance is stabilized at levels only slightly degraded from its initial values.

JEM-EUSO is a space observatory that will be attached to the Japanese module of the International Space Station (ISS) to observe the UV photon tracks produced by Ultra High Energy Cosmic Rays (UHECR) interacting with atmospheric nuclei. The observatory comprises an Atmospheric Monitoring System (AMS) to gather data about the status of the atmosphere, including an infrared camera (IRCAM) for cloud coverage and cloud top height detection. This paper describes the design and characterization tests of IRCAM, which is the responsibility of the Spanish JEM-EUSO Consortium. The core of IRCAM is a 640x480 microbolometer array, the ULIS 04171, sensitive to radiation in the range 7 to 14 microns. The microbolometer array has been tested using the Front End Electronics Prototype (FEEP). This custom designed electronics corresponds to the Breadboard Model, a design built to verify the camera requirements in the laboratory. The FEEP controls the configuration of the microbolometer, digitizes the detector output, sends data to the Instrument Control Unit (ICU), and controls the microbolometer temperature to a 10 mK stability. Furthermore, the FEEP allows IRCAM to preprocess images by the addition of a powerful FPGA. This prototype has been characterized in the laboratories of Instituto de Astrofisica de Canarias (IAC). Main results, including detector response as a function of the scene temperature, NETD and Non-Uniformity Correction (NUC) are shown. Results about thermal resolution meet the system requirements with a NETD lower than 1K including the narrow band filters which allow us to retrieve the clouds temperature using stereovision algorithms.

BATMAN flies is a compact spectro-imager based on MOEMS for generating reconfigurable slit masks, and feeding two arms in parallel. The FOV is 25 x 12 arcmin² for a 1m telescope, in infrared (0.85–1.7μm) and 500-1000 spectral resolution. Unique science cases for Space Observation are reachable with this deep spectroscopic multi-survey instrument: deep survey of high-z galaxies down to H=25 on 5 deg² with continuum detection and all z>7 candidates at H=26.2 over 5 deg²; deep survey of young stellar clusters in nearby galaxies; deep survey of the Kuiper Belt of ALL known objects down to H=22. Pathfinder towards BATMAN in space is already running with ground-based demonstrators.

The far-infrared and submillimeter portions of the electromagnetic spectrum provide a unique view of the astrophysical processes present in the early universe. Our ability to fully explore this rich spectral region has been limited, however, by the size and cost of the cryogenic spectrometers required to carry out such measurements. Micro-Spec (μ-Spec) is a high-sensitivity, direct-detection spectrometer concept working in the 450-1000 μm wavelength range which will enable a wide range of flight missions that would otherwise be challenging due to the large size of current instruments with the required spectral resolution and sensitivity. The spectrometer design utilizes two internal antenna arrays, one for transmitting and one for receiving, superconducting microstrip transmission lines for power division and phase delay, and an array of microwave kinetic inductance detectors (MKIDs) to achieve these goals. The instrument will be integrated on a ~10 cm² silicon chip and can therefore become an important capability under the low background conditions accessible via space and high-altitude borne platforms. In this paper, an optical design methodology for μ-Spec is presented, with particular attention given to its two-dimensional diffractive region, where the light of different wavelengths is focused on the different detectors. The method is based on the maximization of the instrument resolving power and minimization of the RMS phase error on the instrument focal plane. This two-step optimization can generate geometrical configurations given specific requirements on spectrometer size, operating spectral range and performance. Two point designs with resolving power of 260 and 520 and an RMS phase error less than ~0:004 radians were developed for initial demonstration and will be the basis of future instruments with resolving power up to about 1200.

The Spectral and Photometric Imaging Receiver (SPIRE) is one of three scientific instruments on board the European Space Agency's Herschel Space Observatory which ended its operational phase on 29 April 2013. The low to medium resolution spectroscopic capability of SPIRE is provided by an imaging Fourier transform spectrometer (iFTS) of the Mach-Zehnder configuration. With their high throughput, broad spectral coverage, and variable resolution, coupled with their well-defined instrumental line shape and intrinsic wavelength and intensity calibration, iFTS are becoming increasingly common in far-infrared space astronomy missions. The performance of the SPIRE imaging spectrometer will be reviewed and example results presented. The lessons learned from the measured performance of the spectrometer as they apply to future missions will be discussed.

The Exoplanet Characterisation Observatory (EChO) mission was one of the proposed candidates for the European Space Agency’s third medium mission within the Cosmic Vision Framework. EChO was designed to observe the spectra from transiting exoplanets in the 0.55-11 micron band with a goal of covering from 0.4 to 16 microns. The mission and its associated scientific instrument has now undergone a rigorous technical evaluation phase and we report here on the outcome of that study phase, update the design status and review the expected performance of the integrated payload and satellite.

The Exoplanet Characterisation Observatory, EChO, is a dedicated space mission to investigate the physics and chemistry of Exoplanet atmospheres. Using the differential spectroscopy by transit method, it provides simultaneously a complete spectrum in a wide wavelength range between 0.4μm and 16μm of the atmosphere of exoplanets. The payload is subdivided into 6 channels. The mid-infrared channel covers the spectral range between 5μm and 11μm. In order to optimize the instrument response and the science objectives, the bandpass is split in two using an internal dichroic. We present the opto-mechanical concept of the MWIR channel and the detector development that have driven the thermal and mechanical designs of the channel. The estimated end-to-end performance is also presented.

EChO (Exoplanet atmospheres Characterization Observatory), a proposal for exoplanets exploration space mission, is considered the next step for planetary atmospheres characterization. It would be a dedicated observatory to uncover a large selected sample of planets spanning a wide range of masses (from gas giants to super-Earths) and orbital temperatures (from hot to habitable). All targets move around stars of spectral types F, G, K, and M. EChO would provide an unprecedented view of the atmospheres of planets in the solar neighbourhood. The consortium formed by various institutions of different countries proposed as ESA M3 an integrated spectrometer payload for EChO covering the wavelength interval 0.4 to 16 µm. This instrument is subdivided into 4 channels: a visible channel, which includes a fine guidance system (FGS) and a VIS spectrometer, a near infrared channel (SWiR), a middle infrared channel (MWiR), and a long wave infrared module (LWiR). In addition, it contains a common set of optics spectrally dividing the wavelength coverage and injecting the combined light of parent stars and their exoplanets into the different channels. The proposed payload meets all of the key performance requirements detailed in the ESA call for proposals as well as all scientific goals. EChO payload is based on different spectrometers covering the spectral range mentioned above. Among them, SWiR spectrometer would work from 2.45 microns to 5.45 microns. In this paper, the optical and mechanical designs of the SWiR channel instrument are reported on.

The CHaracterising ExOPlanet Satellite (CHEOPS) is a joint ESA-Switzerland space mission (expected to launch in 2017) dedicated to search for exoplanet transits by means of ultra-high precision photometry. CHEOPS will provide accurate radii for planets down to Earth size. Targets will mainly come from radial velocity surveys. The CHEOPS instrument is an optical space telescope of 30 cm clear aperture with a single focal plane CCD detector. The tube assembly is passively cooled and thermally controlled to support high precision, low noise photometry. The telescope feeds a re-imaging optic, which supports the straylight suppression concept to achieve the required Signal to Noise.

“Exo-C” is NASA’s first community study of a modest aperture space telescope designed for high contrast observations of exoplanetary systems. The mission will be capable of taking optical spectra of nearby exoplanets in reflected light, discover previously undetected planets, and imaging structure in a large sample of circumstellar disks. It will obtain unique science results on planets down to super-Earth sizes and serve as a technology pathfinder toward an eventual flagship-class mission to find and characterize habitable exoplanets. We present the mission/payload design and highlight steps to reduce mission cost/risk relative to previous mission concepts. At the study conclusion in 2015, NASA will evaluate it for potential development at the end of this decade.

The nearest solar-type stars are of prime interest for the science of exoplanets because they are the objects most suitable for direct detection and future spectroscopic investigations. Astrometry combined with radial velocity is the technique that can reveal planets with mass as small as the Earth mass in the 1 AU domain. We present in this contribution the result of a 3-year study on a mission capable to perform ultra-precise differential astrometry called NEAT (Nearby Earth Astrometric Telescope) and characterize planetary systems with Earth- mass exoplanets in the vicinity of our Sun. This mission requires exquisite calibration of the focal plane together with innovative approaches to obtain a very stable long focal telescope. This mission will be submitted in 2014 to the ESA M4 Call for Mission.

PROBA-3 is a mission devoted to the in-orbit demonstration of precise formation flying techniques and technologies for future ESA missions. PROBA-3 will fly ASPIICS (Association de Satellites pour l’Imagerie et l’Interferométrie de la Couronne Solaire) as primary payload, which makes use of the formation flying technique to form a giant coronagraph capable of producing a nearly perfect eclipse allowing to observe the sun corona closer to the rim than ever before. The coronagraph is distributed over two satellites flying in formation (approx. 150m apart). The so called Coronagraph Satellite carries the camera and the so called Occulter Satellite carries the sun occulter disc. This paper is reviewing the design and evolution of the ASPIICS instrument as at the beginning of Phase C/D.

The idea behind FIRST (Fibered Imager foR a Single Telescope) is to use single-mode fibers to combine multiple apertures in a pupil plane as such as to synthesize a bigger aperture. The advantages with respect to a pure imager are i) relaxed tolerance on the pointing and cophasing, ii) higher accuracy in phase measurement, and iii) availability of compact, precise, and active single-mode optics like Lithium Niobate. The latter point being a huge asset in the context of a space mission. One of the problems of DARWIN or SIM-like projects was the difficulty to find low cost pathfinders missions. But the fact that Lithium Niobate optic is small and compact makes it easy to test through small nanosats missions. Moreover, they are commonly used in the telecom industry, and have already been tested on communication satellites. The idea of the FIRST-S demonstrator is to spatialize a 3U CubeSat with a Lithium Niobate nulling interferometer. The technical challenges of the project are: star tracking, beam combination, and nulling capabilities. The optical baseline of the interferometer would be 30 cm, giving a 2.2AU spatial resolution at distance of 10 pc. The scientific objective of this mission would be to study the visible emission of exozodiacal light in the habitable zone around the closest stars.

The external starshade is a prospective method for the direct detection and spectral characterization of terrestrial planets around other stars, a key goal identified in ASTRO2010. As part of an ongoing campaign to validate the starlight-suppression performance of the starshade, we present our first results from our most recent desert test campaign, completed June 2, 2014. Our preliminary contrast measurement is ~1x10^-8, consistent with our previous result for the same 60 cm starshade. These data were collected with a 50% spectral bandpass, using a white-light LED as an incoherent light source, in a challenging outdoor test environment. Additional analysis may improve the calculated contrast and/or provide additional improvements to our test configuration, which is currently limited by a halo around the starshade, presumably caused by dust scatter in the atmosphere. The spectral coverage is limited only by the optics and detector in our test setup, not by the starshade itself. Our experimental setup is designed to provide starshade to telescope separation and telescope aperture size that are scaled as closely as possible to the canonical flight system. In this paper we describe key improvements to our test configuration and our latest results with the Hypergaussian starshade. Plans for the next phase of ground testing under a 2013 NASA TDEM award are discussed.

An external occulter is a specially-shaped spacecraft own along the line-of-sight of a space telescope to block starlight before reaching its entrance pupil. Using optimization methods, occulter shapes can be designed to most effectively block starlight. A full-scale occulter cannot be tested on the ground and its performance must be predicted; therefore the fidelity of the optical propagation models used for design and performance prediction must be verified under scaled conditions. In this paper we present both contrast and suppression laboratory measurements for a scaled occulter, and perform a diffractive analysis to determine the factors limiting performance of the laboratory occulter.

This paper provides a survey of the state-of-the-art in coronagraph and starshade technologies and highlights areas where advances are needed to enable future NASA exoplanet missions. An analysis is provided of the remaining technology gaps and the relative priorities of technology investments leading to a mission that could follow JWST. This work is being conducted in support of NASAs Astrophysics Division and the NASA Exoplanet Exploration Program (ExEP), who are in the process of assessing options for future missions. ExEP has funded Science and Technology Definition Teams to study coronagraphs and starshade mission concepts having a lifecycle cost cap of less than $1B. This paper provides a technology gap analysis for these concepts.

Detecting light reflected from exoplanets by direct imaging is the next major milestone in the search for, and characterization of, an Earth twin. Due to the high-risk and cost associated with satellites and limitations imposed by the atmosphere for ground-based instruments, we propose a bottom-up approach to reach that ultimate goal with an endeavor named MAPLE. MAPLE first project is a stratospheric balloon experiment called MAPLE-50. MAPLE-50 consists of a 50 cm diameter off-axis telescope working in the near-UV. The advantages of the near-UV are a small inner working angle and an improved contrast for blue planets. Along with the sophisticated tracking system to mitigate balloon pointing errors, MAPLE-50 will have a deformable mirror, a vortex coronograph, and a self-coherent camera as a focal plane wavefront-sensor which employs an Electron Multiplying CCD (EMCCD) as the science detector. The EMCCD will allow photon counting at kHz rates, thereby closely tracking telescope and instrument-bench-induced aberrations as they evolve with time. In addition, the EMCCD will acquire the science data with almost no read noise penalty. To mitigate risk and lower costs, MAPLE-50 will at first have a single optical channel with a minimum of moving parts. The goal is to reach a few times 109 contrast in 25 h worth of flying time, allowing direct detection of Jovians around the nearest stars. Once the 50 cm infrastructure has been validated, the telescope diameter will then be increased to a 1.5 m diameter (MAPLE-150) to reach 10¹⁰ contrast and have the capability to image another Earth.

Exoplanet coronagraphy will be driven by the telescope architectures available and thus the system designer must have available one or more suitable coronagraphic instrument choices that spans the set of telescope apertures, including filled (off-axis), obscured (e.g. with secondary mirror spiders and struts), segmented apertures, such as JWST, and interferometric apertures. In this work we present one such choice of coronagraph, known as the visible nulling coronagraph (VNC), that spans all four types of aperture and also employs differential sensing and control.

Here we present preliminary results of the integration of two recently proposed vortex coronagraph (VC) concepts for on-axis telescopes on the Stellar Double Coronagraph (SDC) bench behind PALM-3000, the extreme adaptive optics system of the 200-inch Hale telescope of Palomar observatory. The multi-stage vortex coronagraph (MSVC) uses the ability of the vortex to move light in and out of apertures through multiple VC in series to restore the nominal attenuation capability of the charge 2 vortex regardless of the aperture obscurations. The ring-apodized vortex coronagraph (RAVC) is a one-stage apodizer exploiting the VC Lyot-plane amplitude distribution in order to perfectly null the diffraction from any central obscuration size, and for any vortex topological charge. The RAVC is thus a simple concept that makes the VC immune to diffraction effects of the secondary mirror. It combines a vortex phase mask in the image plane with a single pupil-based amplitude ring apodizer, tailor-made to exploit the unique convolution properties of the VC at the Lyot-stop plane. The prototype apodizer uses the same microdot technology that was used to manufacture the apodized pupil Lyot coronagraph (APLC) equipping SPHERE, GPI and P1640.

Space missions, as EChO, or ground based experiments, as SPHERE, have been proposed to measure the atmospheric transmission, reflection and emission spectra. In particular, EChO is foreseen to probe exoplanetary atmospheres over a wavelength range from 0.4 to 16 micron by measuring the combined spectra of the star, its transmission through the planet atmosphere and the emission of the planet. The planet atmosphere characteristics and possible biosignatures will be inferred by studying such composite spectrum in order to identify the emission/absorption lines/bands from atmospheric molecules such as water (H₂O), carbon monoxide (CO), methane (CH₄), ammonia (NH₃) etc. The interpretation of the future EChO observations depends upon the understanding of how the planet atmosphere affects the stellar spectrum and how this last affects the planet emission/absorption. In particular, it is important to know in detail the optical characteristics of gases in the typical physical conditions of the planetary atmospheres and how those characteristics could be affected by radiation induced phenomena such as photochemical and biological one. Insights in this direction can be achieved from laboratory studies of simulated planetary atmosphere of different pressure and temperature conditions under the effects of radiation sources, used as proxies of different bands of the stellar emission.

The European Space Agency (ESA) and e2v, together with the Euclid Imaging Consortium, have designed and manufactured pre-development models of a novel imaging detector for the visible channel of the Euclid space telescope. The new detector is an e2v back-illuminated, 4k x 4k, 12 micron square pixel CCD designated CCD273-84. The backilluminated detectors have been characterised for many critical performance parameters such as read noise, charge transfer efficiency, quantum efficiency, Modulation Transfer Function and Point Spread Function. Initial analysis of the MTF and PSF performance of the detectors has been performed by e2v and at MSSL and the results have enabled the Euclid VIS CCD project to move in to the C/D or flight phase delivery contract. This paper describes the CCD273-84 detector, the test method used for MTF measurements at e2v and the test method used for PSF measurements at MSSL. Results are presented for MTF measurements at e2v over all pre development devices. Also presented is a cross comparison of the data from the MTF and PSF measurement techniques on the same device. Good agreement between the measured PSF Full Width Half Maximum and the equivalent Full Width Half Maximum derived from the MTF images and test results is shown, with results that indicate diffusion FWHM values at or below 10 micron for the CCD273-84 detectors over the spectral range measured. At longer wavelengths the diffusion FWHM is shown to be in the 6-8 micron range.

The Near Infrared Spectrograph and Photometer (NISP) is one of the instruments on board the ESA EUCLID mission. The Universidad Politecnica de Cartagena and Instituto de Astrofisica de Canarias are responsible of the Instrument Control Unit of the NISP (NI-ICU) in the Euclid Consortium. The NI-ICU main functions are: communication with the S/C and the Data Processing Unit, control of the Filter and Grism Wheels, control of the Calibration Unit and thermal control of the instrument. This paper presents the NI-ICU status of definition and design at the end of the preliminary design phase.

Within ESAs 2015 - 2025 Cosmic Vision framework the EUCLID mission satellite addresses cosmological questions related to dark matter and dark energy. EUCLID is equipped with two instruments that are simultaneously observing patches of > 0.5 square degree on the sky. The VIS visual light high spacial resolution imager and the NISP near infrared spectrometer and photometer are separated by a di-chroic beam splitter. Having a large FoV (larger than the full moon disk), together with high demands on the optical performance and strong requirements on in flight stability lead to very challenging demands on alignment and post launch { post cool-down optical element position. The role of an accurate and trust-worthy tolerance analysis which is well adopted to the stepwise integration and alignment concept, as well as to the missions stability properties is therefore crucial for the missions success. With this paper we present a new iteration of the baseline tolerancing concept for EUCLID NISP. All 7 operational modes being low resolution slit-less spectroscopy and three band Y, J& H+ band photometry are being toleranced together. During the design process it was noted that the desired performance can only be reached when alignment and tolerancing methods are closely connected and optimized together. Utilizing computer generated - multi zone - holograms to align and cross reference the four lenses of the NISP optical system. We show our plan to verify these holograms and what alignment sensitivities we reach. In the main section we present the result of the tolerancing and the main contributers that drive the mechanical and thermal design of the NISO optical subsystems. This analysis presents the design status of NISP at the system PDR of the mission.

One of the main challenges for current and near future space experiments is the increase of focal plane complexity in terms of amount of pixels. In the frame work of the ESA Euclid mission to be launched in 2020, the Euclid Consortium is developing an extremely large and stable focal plane for the VIS instrument. CEA has developed the thermomechanical architecture of that Focal Plane taking into account all the very stringent performance and mission related requirements. The VIS Focal Plane Assembly integrates 36 CCDs (operated at 150K) connected to their front end electronics (operated at 280K) as to obtain one of the largest focal plane (∼0.6 billion pixels) ever built for space application after the GAIA one. The CCDs are CCD273 type specially designed and provided by the e2v company under ESA contract, front end electronics is studied and provided by MSSL. In this paper we first recall the specific requirements that have driven the overall architecture of the VIS-FPA and especially the solutions proposed to cope with the scientific needs of an extremely stable focal plane, both mechanically and thermally. The mechanical structure based on SiC material used for the cold sub assembly supporting the CCDs is detailed. We describe also the modular architecture concept that we have selected taking into account AIT-AIV and programmatic constraints.

Euclid is a space mission dedicated to the high-precision study of dark energy and dark matter. Its visible instrument (VIS) will acquire wide field images by means of an array of 36 CCD focal plane detectors. Considering that each acquired full frame produces a huge amount of data (~1.2GByte), an overall daily production of ~120 GByte is expected, which must be compressed to fit the 520 Gbit VIS daily telemetry. Due to the highly demanding science requirements such compression must be rigorously lossless. This software requirement is very hard to meet because of the following constraints: i) the average Compression Ratio (CR) must be greater than 2.8; ii) the activities of data compression inside the Control Data Processing Unit and transmission towards the satellite shall complete in less than 369s, that fits to the acquisition time of the near-infrared instrument; and iii) the compressors parameters as well as the transmission packet size must be tuned to ensure minimal data loss in case of transmission errors. The results obtained with 1D and 2D compression algorithms based on the CCSDS 121 and CCSDS 122 recommended standards, fed with improved focal plane simulations, have been compared to each other. Moreover, a set of various reordering and pre-processing procedures has been applied to the read-out data stream, considering different sizes of the input data segments. The overall scope of these comparative works has been not only to maximize the compression ratio and to minimize the compression time, but also to provide a trade-off between the input data size and the minimum output compressed data segment in order to minimize the data loss due to transmission errors propagation. From our test we found that performing a full (at CCD level) reordering of the read-out data-stream leads to a better compression ratio with both algorithms. The CCSDS 121, however, gives the best results in terms of CR. Finally we found that, for the considered simulated images, the standard pre-processing activities like bias subtraction, bitshift and windowing do not affect the CR significantly. Analogously an additional analysis of the effect of the expected source crowding showed that it is also not important.

In this paper we describe the main requirements driving the development of the Application software of the ICU of NISP, the Near-Infrared Spectro-Photometer of the Euclid mission. This software will be based on a real-time operating system and will interface with all the subunits of NISP, as well as the CMDU of the spacecraft for the Telecommand and Housekeeping management. We briefly detail the services (following the PUS standard) that will be made available, and also possible commonalities in the approach with the ASW of the VIS CDPU, which could make the development effort more efficient; this approach could also make easier the maintenance of the SW during the mission. The development plan of the ASW and the next milestones foreseen are described, together with the architectural design approach and the development environment we are setting up.

In this paper we describe the status of the development of the Data Processing Unit (DPU) of the Near-Infrared Spectro- Photometer (NISP) of the Euclid mission. The architecture of this unit is described, along with the Detector Control Unit (DCU), which operates the 16 HAWAII-2RG (H2RG), composing the NISP Focal Plane Array (FPA), by an equivalent number of SIDECAR systems. The design is evolved from the previous phases, with the implementation of a different approach in the data processing and consequently with the implementation of a large data buffer. The approach in implementing failure tolerance on this unit is described in detail; effort has been made to realize an architecture in which the impact of a single failure can be limited, in the worst case, to the loss of only one detector (out of 16). The main requirements driving the design are also described, in order to emphasize the most challenging areas and the foreseen solutions. The foreseen implementation of the on-board processing pipeline is also described, along with the basic interactions with the Instrument Control Unit (ICU) and with the Mass Memory Unit (MMU). Finally, we outline the on going activity for DPU/DCU bread-boarding.

We report on laboratory demonstrations of a vision-based sensor to aid in the formation flying of suborbital vehicles. Precision formation flying of such vehicles will allow us to hold a starshade external occulter in the line of sight between a telescope and star at large separations. This will enable us to perform the first astronomical demonstrations of starshades as we attempt high-contrast imaging of the outer planetary systems of nearby stars. In this report, we identify two sensor architectures and detail the equations for a closed loop visual feedback system to be used for precision formation flying. We investigate the sensor's expected performance through a suite of Monte Carlo simulations and system-level demonstrations in the lab. We also report on the development and demonstration of a means for visual attitude and position determination.

We have been developing focal-plane phase-mask coronagraphs ultimately aiming at direct detection and characterization of Earth-like extrasolar planets by future space coronagraph missions. By utilizing photonic-crystal technology, we manufactured various coronagraphic phase masks such as eight-octant phase masks (8OPMs), 2nd-order vector vortex masks, and a 4th-order discrete (32-sector) vector vortex mask. Our laboratory experiments show that the 4th-order vortex mask reaches to higher contrast than the 2nd-order one at inner region on a focal plane. These results demonstrate that the higher-order vortex mask is tolerant of low-order phase aberrations such as tip-tilt errors. We also carried out laboratory demonstration of the 2nd-order vector vortex masks in the High-Contrast Imaging Testbed (HCIT) at the Jet Propulsion Laboratory (JPL), and obtained 10^-8-level contrast owing to an adaptive optics system for creating dark holes. In addition, we manufactured a polarization-filtered 8OPM, which theoretically realizes achromatic performance. We tested the manufactured polarization-filtered 8OPM in the Infrared Coronagraphic Testbed (IRCT) at the JPL. Polychromatic light sources are used for evaluating the achromatic performance. The results suggest that 10^-5- level peak-to-peak contrasts would be obtained over a wavelength range of 800-900 nm. For installing the focal-plane phase-mask coronagraph into a conventional centrally-obscured telescope with a secondary mirror, pupil-remapping plates have been manufactured for removing the central obscuration to enhance the coronagraphic performance. A result of preliminary laboratory demonstration of the pupil-remapping plates is also reported. In this paper, we present our recent activities of the photonic-crystal phase coronagraphic masks and related techniques for the high-contrast imaging.

Direct imaging of extra-solar planets has now become a reality, especially with the deployment and commissioning of the first generation of specialized ground-based instruments such as the GPI, SPHERE, P1640 and SCExAO. These systems will allow detection of planets 10⁷ times fainter than their host star. For space- based missions, such as EXCEDE, EXO-C, EXO-S, WFIRST/AFTA, different teams have shown in laboratories contrasts reaching 10^-10 within a few diffraction limits from the star using a combination of a coronagraph to suppress light coming from the host star and a wavefront control system. These demonstrations use a de- formable mirror (DM) to remove residual starlight (speckles) created by the imperfections of telescope. However, all these current and future systems focus on detecting faint planets around a single host star or unresolved bi- naries/multiples, while several targets or planet candidates are located around nearby binary stars such as our neighbor star Alpha Centauri. Until now, it has been thought that removing the light of a companion star is impossible with current technology, excluding binary star systems from target lists of direct imaging missions. Direct imaging around binaries/multiple systems at a level of contrast allowing Earth-like planet detection is challenging because the region of interest, where a dark zone is essential, is contaminated by the light coming from the hosts star companion. We propose a method to simultaneously correct aberrations and diffraction of light coming from the target star as well as its companion star in order to reveal planets orbiting the target star. This method works even if the companion star is outside the control region of the DM (beyond its half-Nyquist frequency), by taking advantage of aliasing effects.

We have carried out a study of the performance of high-contrast coronagraphs in the presence of mask defects. We have considered the effects of opaque and dielectric particles of various dimensions, as well as systematic mask fabrication errors and the limitations of material properties in creating dark holes. We employ sequential deformable mirrors to compensate for phase and amplitude errors, and show the limitations of this approach in the presence of coronagraph image-mask defects.

A major component of the estimation and correction of starlight at very high contrasts is the creation of a dark hole: a region in the vicinity of the core of the stellar point spread function (PSF) where speckles in the PSF wings have been greatly attenuated, up to a factor of 10¹⁰ for the imaging of terrestrial exoplanets. At these very high contrasts, removing these speckles requires distinguishing between light from the stellar PSF scattered by instrument imperfections, which may be partially corrected across a broad band using deformable mirrors in the system, from light from other sources which generally may not. These other sources may be external or internal to the instrument (e.g. planets, exozodiacal light), but in either case, their distinguishing characteristic is their inability to interfere coherently with the PSF. In the following we discuss the estimation, structure, and expected origin of this incoherent" signal, primarily in the context of a series of experiments made with a linear band-limited mask in Jan-Mar 2013. We find that the incoherent" signal at moderate contrasts is largely estimation error of the coherent signal, while at very high contrasts it represents a true floor which is stable over week-timescales.

Direct observations of habitable zone exoplanets within 10 pc require very high contrast attenuation of the parent star. While "pale blue dot" earth twins have strong signals in the near-UV and blue portion of the spectrum, and a G-class star like our sun has the most energy in the same region, the contrast ratio of star to exoplanet is 10¹⁰. However the ratio is 10⁸ when the exoplanet albedo is reflecting an emission band inside of the spectrum of the star's absorption band. These interlaced emission and absorption bands are numerous and sharply defined in the blue region when the system is viewed through circular diffractive pupil optics. We show how to use a circular diffraction grating pupil to create asymmetrical circular diffraction images of exoplanetary systems that can be extracted from the central star's perfectly circular diffraction pattern by a series of iterative data reduction steps. We present a model of the apparatus that forms the diffraction images and a demonstration of the process in a laboratory experiment. The process may prove useful if large circular diffractive optic telescopes are successfully fabricated in on-going projects for earth reconnaissance from GEO where 10 meter diffractive optic telescopes are now contemplated.

We have studied a coronagraph system with an unbalanced nulling interferometer (UNI). An important characteristic is a pre-reduction of the star light to 1/100 at the UNI stage which enables to enhance the final contrast. In other point of view, the UNI stage magnifies the wavefront aberrations, which lead us to compensate for the wavefront aberrations beyond the AO systems capabilities. It consists of the UNI, adaptive optics, and a coronagraph. In our experiments, we have observed the extra speckle reduction of better than 0.07 by the advantage of the UNI system. In order to obtain better contrast, we planned to reconstruct all of the optics, which use UNI with 4QPM, a coronagraph with 8OPM or VVM, a dual feedback control method, and a wavefront correction inside the UNI by an upstream AO.

A stellar coronagraph system for direct observations of extra solar planets is under development by combining unbalanced nulling interferometer (UNI), adaptive optics, and a focal plane mask coronagraph^1,2,3,4,5,6. It can reach a high contrast as using λ/10000 precision optics by λ/1000 quality ones. However, a sufficient high contrast is not obtained yet in the experiment before. It is thought that the remained speckle noise at the final coronagraph focal plane detector are produced by a “non-common path error” of λ/100 level, which is a wavefront error of the coronagraph different from that of a wavefront sensor (WFS) of adaptive optics, even when the WFS indicates λ/1000 conversion. The non-common path error can be removed by the dark zone method that is the way of wavefront correction by wavefront sensing at the final focal plane detector, although it has an issue of operation for very faint targets because of a slow feedback loop. In the present paper, we describe that our coronagraph system becomes practically higher contrast by upgrading the control method of deformable mirror (DM) with the WFS assisted by final focal plane wavefront sensing method. We accomplished contrast of 8×10^-7 relative to the star in experiment.

The Exoplanet Characterisation Observatory (EChO) is a space project currently under study by ESA in the context of a medium class mission within the Cosmic Vision programme for launch post 2020. The EChO main scientific objectives are based on spectroscopy of transiting exoplanets over a wide range of wavelengths, from visible to mid-infrared. The high sensitivity requirements of the mission need an extremely stable thermo-mechanical platform. In this paper we describe the thermal architecture of the payload and discuss the main requirements that drive the design. The instrument is passively cooled to a temperature close to 45K, together with the telescope, to achieve the required sensitivity and photometric stability. Passive cooling is achieved by a V-Groove based design that exploits the L2 orbit favorable thermal conditions. The Visible and short-IR wavelength detectors are maintained at the operating temperature of 40K by a dedicated radiator coupled to cold space. The mid-IR channels require lower temperature references for both the detectors and part of the optical units. These colder stages are provided by an active cooling system based on a Neon Joule-Thomson cold end, fed by a mechanical compressor, able to reach temperatures <30K. The design has to be compliant with the severe requirements on thermal stability of the optical and detector units. The periodical perturbations due to orbital changes, to the cooling chain or to other internal instabilities make the temperature control one of the most critical issues of the whole architecture. The thermal control system design, based on a combination of passive and active solutions needed to maintain the required stability at the detector stages level is described. We report here about the baseline thermal architecture at the end of the Study Phase, together with the main trade-offs needed to enable the EChO exciting science in a technically feasible payload design. Thermal modeling results and preliminary performance predictions in terms of steady state and transient behavior are also discussed. This paper is presented on behalf of the EChO Consortium.

Vega is one of only a few stars calibrated against an SI-traceable blackbody, and is the historical flux standard. Photometric zeropoints of the Hubble Space Telescope’s instruments rely on Vega, through the transfer of its calibration via stellar atmosphere models to the suite of standard stars. HST’s recently implemented scan mode has enabled us to develop a path to an absolute SI traceable calibration for HST IR observations. To fill in the crucial gap between 0.9 and 1.7 micron in the absolute calibration, we acquired -1st order spectra of Vega with the two WFC3 infrared grisms. At the same time, we have improved the calibration of the -1st orders of both WFC3 IR grisms, as well as extended the dynamic range of WFC3 science observations by a factor of 10000. We describe our progress to date on the WFC3 ‘flux calibration ladder’ project to provide currently needed accurate zeropoint measurements in the IR

We propose an architecture for the control system of BETTII,¹ a far-infrared, balloon-borne interferometer with a baseline of 8 meters. This system involves multiple synchronized control loops for real-time pointing control and precise attitude knowledge. This will enable accurate phase estimation and control, a necessity for successful interferometry. We present the overall control strategy and describe our flight hardware in detail. We also show our current test setup and the first results of our coarse pointing loop.

JANUS (Jovis, Amorum ac Natorum Undique Scrutator) is the visible camera selected for the ESA JUICE mission to the Jupiter system. Resources constraints, S/C characteristics, mission design, environment and the great variability of observing conditions for several targets put stringent constraints on instrument architecture. In addition to the usual requirements for a planetary mission, the problem of mass and power consumption is particularly stringent due to the long-lasting cruising and operations at large distance from the Sun. JANUS design shall cope with a wide range of targets, from Jupiter atmosphere, to solid satellite surfaces, exosphere, rings, and lightning, all to be observed in several color and narrow-band filters. All targets shall be tracked during the mission and in some specific cases the DTM will be derived from stereo imaging. Mission design allows a quite long time range for observations in Jupiter system, with orbits around Jupiter and multiple fly-bys of satellites for 2.5 years, followed by about 6 months in orbit around Ganymede, at surface distances variable from 10⁴ to few hundreds km. Our concept was based on a single optical channel, which was fine-tuned to cover all scientific objectives based on low to high-resolution imaging. A catoptric telescope with excellent optical quality is coupled with a rectangular detector, avoiding any scanning mechanism. In this paper the present JANUS design and its foreseen scientific capabilities are discussed.

One of the key goals of NASA’s astrophysics program is to answer the question: How did galaxies evolve into the spiral, elliptical, and irregular galaxies that we see today? We describe a space mission concept called Galaxy Evolution Spectroscopic Explorer (GESE) to help address this question by making a large ultraviolet spectroscopic survey of galaxies at a redshift, z~1 (look-back time of ~8 billion years). GESE is a 1.5-m space telescope with an near-ultraviolet (NUV) multi-object slit spectrograph covering the spectral range, 0.2-0.4 μm (0.1-0.2 μm as emitted by galaxies at a redshift, z~1) at a spectral resolution of Δλ=6 Å.

Fluctuations in the extragalactic background light trace emission from the history of galaxy formation, including the emission from the earliest sources from the epoch of reionization. A number of recent near-infrared measure- ments show excess spatial power at large angular scales inconsistent with models of z < 5 emission from galaxies. These measurements have been interpreted as arising from either redshifted stellar and quasar emission from the epoch of reionization, or the combined intra-halo light from stars thrown out of galaxies during merging activity at lower redshifts. Though astrophysically distinct, both interpretations arise from faint, low surface brightness source populations that are difficult to detect except by statistical approaches using careful observations with suitable instruments. The key to determining the source of these background anisotropies will be wide-field imaging measurements spanning multiple bands from the optical to the near-infrared. The Cosmic Infrared Background ExpeRiment 2 (CIBER-2) will measure spatial anisotropies in the extra- galactic infrared background caused by cosmological structure using six broad spectral bands. The experiment uses three 2048 x 2048 Hawaii-2RG near-infrared arrays in three cameras coupled to a single 28.5 cm telescope housed in a reusable sounding rocket-borne payload. A small portion of each array will also be combined with a linear-variable filter to make absolute measurements of the spectrum of the extragalactic background with high spatial resolution for deep subtraction of Galactic starlight. The large field of view and multiple spectral bands make CIBER-2 unique in its sensitivity to fluctuations predicted by models of lower limits on the luminosity of the first stars and galaxies and in its ability to distinguish between primordial and foreground anisotropies. In this paper the scientific motivation for CIBER-2 and details of its first flight instrumentation will be discussed, including detailed designs of the mechanical, cryogenic, and electrical systems. Plans for the future will also be presented.

The Primary Mirror (PM) of NASA’s James Webb Space Telescope (JWST) consists of 18 segment assemblies that are aligned on-orbit using hexapod actuators to function as a single monolithic optic. The individual segment assemblies are polished into one of three different prescriptions. Each segment of a given prescription may be placed in one of six different locations for that prescription, resulting in tens of millions of possible placement combinations of the 18 segments on the backplane of the telescope. A method is proposed to optimize the placement based on minimizing the known alignment offsets of as-built mirrors in combination with the predicted shifts of each attachment point on the telescope backplane due to material creep, cool down shifts, launch shifts, and gravity release. The optimization routine can be configured to allow for minimization of errors in any of the six rigid-body degrees of freedom and can further reduce selection options based on defined hardware constraints. Such a routine can be utilized to minimize initial misalignments of the PM on-orbit, reducing the need to exercise mirror actuators to achieve an aligned state. The end result is reduced commissioning time and increased probability of success of the mission.

The James Webb Space Telescope (JWST) is a large cryogenic telescope observing over a spectral range from 0.6 μm to 29 μm. A large sun shield blocks sunlight and provides thermal isolation for the optics. Analyses characterizing the stray light reaching the instrument focal planes from the galactic sky, zodiacal background, bright objects near the line-of-sight, and earth and moon shine are presented along with the self-generated thermal infrared background from Observatory structures. The latter requires thermal analysis to characterize the Observatory temperatures. Dependencies on the surface properties of BRDF and emittance are discussed for the underlying materials and the effects of contamination

The James Webb Telescope (JWST) is a large cryo-optical system. Many critical thermal control or optical surfaces are exposed to ground and flight environments and are expected to be contaminated to some level. In order to calculate key system performance parameters, such as stray light and radiative thermal transfer, the emissivity must be known in terms of contamination level and temperature. This paper will introduce the methods of determining these emissivities, and the discussion will cover the types of particulate and molecular contamination expected on JWST. The results of the calculations will be introduced and discussed.

We present the results of ongoing coronagraphic simulations aimed at designing strategies for optimizing oper- ations of the coronagraphs in the mid-infrared instrument (MIRI) on-board the James Webb Space Telescope (JWST). In particular, the adverse effects on the point spread function caused by the phase mask coronagraphs and the observatory slew accuracy are known to limit our ability to position stars at the center of the coron- agraph. Here, we investigate these two effects on our ability to perform target acquisition (TA) and consider different scenarios involving single and multiple acquisitions to mitigate them. We assess the performance of the coronagraphs under various slew accuracy models as well as noise sources. In general, we find that scenarios that require fewer acquisitions yield final positions with smaller dispersions but larger offsets. Our Single TA scenario yields the best repeatability for all three slew accuracy models that we considered although a dual Twin TA strategy generally yields more accurate centering. We also investigate the use of the contamination control cover (CCC) inside MIRI during TA of bright objects, and ways to mitigate the resulting latent images when the CCC is not used. Our results are expressed in terms of achieved contrast with simple, single reference star subtraction. Given our preliminary prescription for latency, our simulations suggest that the CCC need not be used except for very bright sources; detailed guidelines will require additional information on the latent image decay time scale. Furthermore, we find that contrast is dependent on the observatory slew accuracy at any wavelength. The highest contrast is achieved with the highest slew accuracy model, although the background photon noise limits the contrast at longer wavelengths.

We present several engineering and algorithmic aspects of non-redundant masking (NRM) as they pertain to the James Webb Space Telescope (JWST). NRM's fundamental data structures have multiple uses in wavefront sensing as well in as high resolution imaging. Kernel phases are a full aperture generalization of NRM applicable to moderate and high Strehl ratio images. Eigenphases, the complement to kernel phases, provide wavefront sensing with single in-focus images. Thus this set of phases is relevant to wavefront sensing with routine science images on any Nyquist-sampled science camera on JWST. We attempt to organize these apparently diverse aspects of such Fizeau interferometry into an inter-related picture in order to facilitate their development and potential use on JWST and future space telescopes.

The JamesWebb Space Telescope (JWST) Optical Simulation Testbed (JOST) is a tabletop experiment designed to reproduce the main aspects of wavefront sensing and control (WFS and C) for JWST. To replicate the key optical physics of JWST’s three-mirror anastigmat (TMA) design at optical wavelengths we have developed a three-lens anastigmat optical system. This design uses custom lenses (plano-convex, plano-concave, and bi-convex) with fourth-order aspheric terms on powered surfaces to deliver the equivalent image quality and sampling of JWST NIRCam at the WFS and C wavelength (633 nm, versus JWST’s 2.12 μm). For active control, in addition to the segmented primary mirror simulator, JOST reproduces the secondary mirror alignment modes with five degrees of freedom. We present the testbed requirements and its optical and optomechanical design. We study the linearity of the main aberration modes (focus, astigmatism, coma) both as a function of field point and level of misalignments of the secondary mirror. We find that the linearity with the transmissive design is similar to what is observed with a traditional TMA design, and will allow us to develop a linear-control alignment strategy based on the multi-field methods planned for JWST.

For large space missions maximizing the time spent observing science targets by minimizing overhead increases the scientific return of the mission. On the James Webb Space Telescope (JWST), the baseline mode of resetting the near infrared detectors is a pixel-by-pixel reset. For the Hawaii-2RG detectors this requires 10.5 seconds. Over the life of the mission, 2-3% of the total time is spent performing these resets. In this paper, we investigate using the much faster row-by- row reset mode of the Hawaii-2RG as an alternative. Resets in this mode can be performed in only 40 milliseconds allowing more time for science. We investigate how the changing of the reset modes affects: thermal stability of the detectors, total noise, and observed persistence after bright sources are observed. Overall, any negative side effects seem to be outweighed by the increase in the available exposure time for science during the lifetime of JWST.

Coronagraphic Target Acquisition (TA) is an important factor that contributes to the contrast performance and typically depends on the coronagraph design. In the case of JWST, coronagraphic TAs rely on measuring the centroid of the star's point spread function away from the focal plane mask, and performing a small angle ma- neuver (SAM), to place the star behind the coronagraphic mask. Therefore, the accuracy of the TA is directly limited by the SAM accuracy. Typically JWST coronagraphic observations will include the subtraction of a reference (either a reference star, or a self-reference after a telescope roll). With such differential measurement, the reproducibility of the TA is a very important factor. We propose a novel coronagraphic observation concept whereby the reference PSF is first acquired using a standard TA, followed by coronagraphic observations of a reference star on a small grid of dithered positions. Sub-pixel dithers (5-10 mas each) provide a small reference PSF library that samples the variations in the PSF as a function of position relative to the mask, thus compen- sating for errors in the TA process. This library can be used for PSF subtraction with a variety of algorithms (e.g; LOCI or KLIP algorithms, Lafrenière et al. 2007; Soummer, Pueyo and Larkin 2012). These sub-pixel dithers are executed under closed-loop fine guidance, unlike a standard SAM that executes the maneuver in coarse point mode, which can result in a temporary target offset of 1 arcsecond and would bring the star out from behind the coronagraphic mask. We discuss and evaluate the performance gains from this observation scenario compared to the standard TA both for MIRI coronagraphs.

Accurate models of optical performance are an essential tool for astronomers, both for planning scientific observations ahead of time, and for a wide range of data analysis tasks such as point-spread-function (PSF)-fitting photometry and astrometry, deconvolution, and PSF subtraction. For the James Webb Space Telescope, the WebbPSF program provides a PSF simulation tool in a flexible and easy-to-use software package available to the community and implemented in Python. The latest version of WebbPSF adds new support for spectroscopic modes of JWST NIRISS, MIRI, and NIRSpec, including modeling of slit losses and diffractive line spread functions. It also provides additional options for modeling instrument defocus and/or pupil misalignments. The software infrastructure of WebbPSF has received enhancements including improved parallelization, an updated graphical interface, a better configuration system, and improved documentation. We also present several comparisons of WebbPSF simulated PSFs to observed PSFs obtained using JWST's flight science instruments during recent cryovac tests. Excellent agreement to first order is achieved for all imaging modes cross-checked thus far, including tests for NIRCam, FGS, NIRISS, and MIRI. These tests demonstrate that WebbPSF model PSFs have good fidelity to the key properties of JWST's as-built science instruments.

We present a general algorithm to perform the linear fit of non-destructive ramps, the most common readout mode of IR detectors in Astronomy. The algorithm is based on the Generalized Least Square Method, appropriate when the data are heteroscedastic and correlated, and uses a covariance matrix accounting for readout noise, correlated Poisson noise of the integrated signal, group-averages, and digitization noise. The basic algorithm is expanded to allow for detection and removal of cosmic rays within the ramp on solid statistical ground. The procedure returns a statistically accurate estimate of the ramp’s slope, intercept and of the intensity of possible cosmic rays together with their associated uncertainties and correlation terms. An example of implementation exploiting IDL’s matrix operators is provided in the Appendix.

JWST’s Near-Infrared Imager and Slitless Spectrograph (NIRISS) includes an Aperture Masking Interferometry (AMI) mode designed to be used between 2.7μm and 4.8μm. At these wavelengths, it will have the highest angular resolution of any mode on JWST, and, for faint targets, of any existing or planned infrastructure. NIRISS AMI is uniquely suited to detect thermal emission of young massive planets and will permit the characterization of the mid-IR flux of exoplanets discovered by the GPI and SPHERE adaptive optics surveys. It will also directly detect massive planets found by GAIA through astrometric accelerations, providing the first opportunity ever to get both a mass and a flux measurement for non-transiting giant planets. NIRISS AMI will also enable the study of the nuclear environment of AGNs.

In the context of a stereo-camera, measuring the image quality allows to define the accuracy of the 3D reconstruction. In fact, depending on the precision of the camera position data, on the kind of reconstruction algorithm, and on the adopted camera model, it determines the vertical accuracy of the reconstructed terrain model. Aim of this work is to describe the results and the method implemented to determine the Line Spread Function (LSF) of the Stereoscopic Channel (STC) of the SIMBIOSYS imaging system for the BepiColombo mission. BepiColombo is the cornerstone mission n.5 of the European Space Agency dedicated to the exploration of the innermost planet of the Solar System, Mercury, and it is expected to be launched in 2016. STC is a double push-frame single-detector camera composed by two identical sub-channels looking at ±21° wrt the nadir direction. STC has been designed so to have many optical elements common to both sub-channels. Also the image focal plane is common to the sub-channels and this permits the use of a single detector for the acquisition of the two images, i.e. one for each viewing direction. Considering the novelty of the design, conceived to sustain a harsh environment and to be as compact as possible, the STC unit is very complex. To obtain the most accurate 3D reconstruction of the Mercury surface, a camera model as precise as possible is needed, and an ad-hoc calibration set-up has been designed to calibrate the instrument both from the usual geometrical and radiometrical points of view and more specifically for the instrument stereo capability. In this context LSF estimation was performed with a new method applying a particular oversampling approach for the curve fitting to determine at first the entire calibration system transfer function and at the end the optical properties of the single instrument.

The Earth’s atmosphere introduces a spatial frequency filtering in the object images recorded with ground-based instruments. A solution is to observe with telescopes onboard satellites to avoid atmospheric effects and to obtain diffraction limited images. However, similar atmosphere problems encountered with ground-based instruments may subsist in space when we observe the Sun since thermal gradients at the front of the instrument affect the observations. We present in this paper some simulations showing how solar images recorded in a telescope focal plane are directly impacted by thermal gradients in its pupil plane. We then compare the results with real solar images recorded with the PICARD mission in space.

The JANUS (Jovis, Amorum ac Natorum Undique Scrutator) will be the on board camera of the ESA JUICE satellite dedicated to the study of Jupiter and its moons, in particular Ganymede and Europa. This optical channel will provide surface maps with plate scale of 15 microrad/pixel with both narrow and broad band filters in the spectral range between 0.35 and 1.05 micrometers over a Field of View 1.72 × 1.29 degrees². The current optical design is based on TMA design, with on-axis pupil and off-axis field of view. The optical stop is located at the secondary mirror providing an effective collecting area of 7854 mm² (100 mm entrance pupil diameter) and allowing a simple internal baffling for first order straylight rejection. The nominal optical performances are almost limited by the diffraction and assure a nominal MTF better than 63% all over the whole Field of View. We describe here the optical design of the camera adopted as baseline together with the trade-off that has led us to this solution.

SIMBIOSYS is a highly integrated instrument suite that will be mounted on-board BepiColombo, which is the fifth cornerstone mission of the European Space Agency dedicated to the exploration of the planet Mercury and it is expected to be launched in 2016. The SIMBIOSYS instrument consists of three channels: the STereo imaging Channel (STC), with broad spectral bands in the 400–950 nm range and medium spatial resolution (up to 50 m/px); the High Resolution Imaging Channel (HRIC), with broad spectral bands in the 400–900 nm range and high spatial resolution (up to 5 m/px), and the Visible and near- Infrared Hyperspectral Imaging channel (VIHI), with high spectral resolution (up to 6 nm) in the 400–2000 nm range and spatial resolution up to 100 m/px. The on-ground calibration system has to cover the full spectral range of the instrument, i.e. from 400 to 2000 nm, and the emitted radiance has to vary over a range of four decades to account for both simulations of Mercury surface acquisition and star field observations. The methods and the results of the measurements done to calibrate the integrating sphere needed for the on-ground radiometric testing of the SIMBIOSYS instrument will be given and discussed. Temporal stability, both on short and long periods, spatial and spectral uniformity, and the emitted radiance for different lamp configurations and different shutter apertures have been measured. The results of the data analysis confirm that the performance of the integrating sphere is well suited for the radiometric calibration of all the three different channels of the SIMBIOSYS instrument.

The Japanese SPace Infrared telescope for Cosmology and Astrophysics (SPICA), a 3 m class telescope cooled to ~ 6 K, will provide extremely low thermal background far-infrared observations. An imaging Fourier transform spectrometer (SAFARI) is being developed to exploit the low background provided by SPICA. Evaluating the performance of the interferometer translation stage and key optical components requires a cryogenic test facility. In this paper we discuss the design challenges of a pulse tube cooled cryogenic test facility that is under development for this purpose. We present the design of the cryostat and preliminary results from component characterization and external optical metrology.

IRAP is developing the warm electronic, so called Detector Control Unit" (DCU), in charge of the readout of the SPICA-SAFARI's TES type detectors. The architecture of the electronics used to readout the 3 500 sensors of the 3 focal plane arrays is based on the frequency domain multiplexing technique (FDM). In each of the 24 detection channels the data of up to 160 pixels are multiplexed in frequency domain between 1 and 3:3 MHz. The DCU provides the AC signals to voltage-bias the detectors; it demodulates the detectors data which are readout in the cold by a SQUID; and it computes a feedback signal for the SQUID to linearize the detection chain in order to optimize its dynamic range. The feedback is computed with a specific technique, so called baseband feedback (BBFB) which ensures that the loop is stable even with long propagation and processing delays (i.e. several µs) and with fast signals (i.e. frequency carriers at 3:3 MHz). This digital signal processing is complex and has to be done at the same time for the 3 500 pixels. It thus requires an optimisation of the power consumption. We took the advantage of the relatively reduced science signal bandwidth (i.e. 20 - 40 Hz) to decouple the signal sampling frequency (10 MHz) and the data processing rate. Thanks to this method we managed to reduce the total number of operations per second and thus the power consumption of the digital processing circuit by a factor of 10. Moreover we used time multiplexing techniques to share the resources of the circuit (e.g. a single BBFB module processes 32 pixels). The current version of the firmware is under validation in a Xilinx Virtex 5 FPGA, the final version will be developed in a space qualified digital ASIC. Beyond the firmware architecture the optimization of the instrument concerns the characterization routines and the definition of the optimal parameters. Indeed the operation of the detection and readout chains requires to properly define more than 17 500 parameters (about 5 parameters per pixel). Thus it is mandatory to work out an automatic procedure to set up these optimal values. We defined a fast algorithm which characterizes the phase correction to be applied by the BBFB firmware and the pixel resonance frequencies. We also defined a technique to define the AC-carrier initial phases in such a way that the amplitude of their sum is minimized (for a better use of the DAC dynamic range).

SPICA (Space Infrared Telescope for Cosmology and Astrophysics) is an astronomical mission optimized for mid- and far-infrared astronomy with a 3-m class telescope which is cryogenically cooled to be less than 6 K. The SPICA mechanical cooling system is indispensable for the mission but, generates micro-vibrations which could affect to the pointing stability performances. Activities to be undertaken during a risk mitigation phase (RMP) include consolidation of micro-vibration control design for the satellite, as well as a number of breadboarding activities centered on technologies that are critical to the success of the mission. This paper presents the RMP activity results on the microvibration control design.

The contamination control for the next-generation space infrared observatory SPICA is presented. The optical performance of instruments on space observatories are often degraded by particulate and/or molecular contamination. Therefore, the contamination control has a potential to produce a significant risk, and it should be investigated in the risk mitigation phase of the SPICA development. The requirements from contamination- sensitive components onborad SPICA, the telescope assembly and focal plane instruments, are summarized. Possible contamination sources inside and outside the SPICA spacecraft were investigated. Based on impact on the SPICA system design, the following contamination sources were extensively studied through simulation and measurement; (1) outgassing from the payload module surrounding the telescope mirror and focal plane instruments, (2) contamination due to the thruster plume, and (3) environmental contamination during the integration, storage and verification phases. Although the outgas from the payload module and the thruster plume were estimated to produce only a negligible influence, the environmental contamination was suggested to affect significantly the telescope and focal plane instruments. Reasonable countermeasures to reduce the environmental contamination were proposed, some of which were confirmed to be actually effective.

The Space Infrared Telescope for Cosmology and Astrophysics (SPICA) is a pre-project of JAXA in collaboration with ESA to be launched around 2025. The SPICA mission is to be launched into a halo orbit around the second Lagrangian point in the Sun-Earth system, which allows us to use effective radiant cooling in combination with a mechanical cooling system in order to cool a 3m large IR telescope below 6K. The use of 4K / 1K-class Joule-Thomson coolers is proposed in order to cool the telescope and provide a 4K / 1K temperature region for Focal Plane Instruments (FPIs). This paper introduces details of the thermal design study for the SPICA payload module in the Risk-Mitigation-Phase (RMP), in which the activity is focused on mitigating the mission’s highest risks. As the result of the RMP activity, most of all the goals have been fully satisfied and the thermal design of the payload module has been dramatically improved.

The scientific goals of the far-infrared astronomy mission SPICA challenge the design of a large-stroke imaging FTS for Safari, inviting for the development of a new generation of cryogenic actuators with very low dissipation. In this paper we present the Fourier Transform Spectrometer (FTS) system concept, as foreseen for SPICA-Safari, and we discuss the technical developments required to satisfy the instrument performance.

This paper describes the optical design of the far infrared imaging spectrometer for the JAXA’s SPICA mission. The SAFARI instrument, is a cryogenic imaging Fourier transform spectrometer (iFTS), designed to perform backgroundlimited spectroscopic and photometric imaging in the band 34-210 μm. The all-reflective optical system is highly modular and consists of three main modules; input optics module, interferometer module (FTS) and camera bay optics. A special study has been dedicated to the spectroscopic performance of the instrument, in which the spectral response and interference of the instrument have been modeled, as the FTS mechanism scans over the total desired OPD range.

This communication presents the feasibility study of an image slicer for future space missions, especially for the integral field unit (IFU) of the SUVIT (Solar UV-Visible-IR telescope) spectro-polarimeter on board the Japanese-led solar space mission Solar-C as a backup option. The MuSICa (Multi-Slit Image slicer based on collimator-Camera) image slicer concept, originally developed for the European Solar Telescope, has been adapted to the SUVIT requirements. The IFU will reorganizes a 2-D field of view of 10 x 10 arcsec² into three slits of 0.18 arcsec width by 185.12 arcsec length using flat slicer mirrors of 100 μm width. The layout of MuSICa for Solar-C is telecentric and offers an optical quality limited by diffraction. The entrance for the SUVIT spectro-polarimeter is composed by the three IFU slits and one ordinal long slit to study, using high resolution spectro-polarimetry, the solar atmosphere (Photosphere and Chromosphere) within a spectral range between 520 nm (optionally 280 nm) and 1,100 nm.

This paper describes the Electrical Ground Support Equipment (EGSE) of the Dust characterization, Risk assessment, and Environment Analyser on the Martian Surface (DREAMS) scientific instrument, an autonomous surface payload package to be accommodated on the Entry, Descendent and landing Module (EDM) of the ExoMars 2016 European Space Agency (ESA) mission. DREAMS will perform several kinds of measurements, such as the solar irradiance with different optical detectors in the UVA band (315-400nm), NIR band (700-1100nm) and in "total luminosity" (200 –1100 nm). It will also measure environmental parameters such as the intensity of the electric field, temperature, pressure, humidity, speed and direction of the wind. The EGSE is built to control the instrument and manage the data acquisition before the integration of DREAMS within the Entry, Descendent and landing Module (EDM) and then to retrieve data from the EDM Central Checkout System (CCS), after the integration. Finally it will support also the data management during mission operations. The EGSE is based on commercial off-the-shelf components and runs custom software. It provides power supply and simulates the spacecraft, allowing the exchange of commands and telemetry according to the protocol defined by the spacecraft prime contractor. This paper describes the architecture of the system, as well as its functionalities to test the DREAMS instrument during all development activities before the ExoMars 2016 launch.

The Visible and Near Infrared (VNIR) is one of the modules of EChO, the Exoplanets Characterization Observatory proposed to ESA for an M-class mission. EChO is aimed to observe planets while transiting by their suns. Then the instrument has be designed to assure a high efficiency over the whole spectral range. In fact, it has to be able to observe stars with an apparent magnitude M_v= 9÷12 and able to see contrasts of 10^-4÷10^-5 in order to reveal the characteristics of the atmospheres of the exoplanets under investigation. VNIR was originally designed for covering the spectral range from 0.4 to 1.0 μm [1] but now the design has been reviewed and its spectral range has been extended up to 2.5 μm. It is a spectrometer in a cross-dispersed configuration that, then, uses the combination of a diffraction grating and a prism to spread the light in different wavelengths and in a useful number of orders of diffraction. Its resolving power is about 330 over the entire spectral range and its field of view is approximately 2 arcsec. The spectrometer is functionally split into two channels respectively working in the 0.4-1.0 μm and 1.0-2.5 μm spectral ranges. Such a solution is imposed by the fact the light at low wavelengths has to be shared with the EChO Fine Guiding System (FGS) devoted to the pointing of the stars under observation. The instrument works at 45K and its weight is 6 kg.