This PDF file contains the front matter associated with SPIE Proceedings Volume 9881, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

NASA-ISRO Synthetic Aperture Radar (NISAR), a novel SAR concept will be utilized to image wide swath at high resolution of stripmap SAR. It will have observations in L- and S-bands to understand highly spatial and temporally complex processes such as ecosystem disturbances, ice sheet changes, and natural hazards including earthquakes, tsunamis, volcanoes, and landslides. NISAR with several advanced features such as 12 days interferometric orbit, achievement of high resolution and wide swath images through SweepSAR technology and simultaneous data acquisition in dual frequency would support a host of applications. The primary objectives of NISAR are to monitor ecosystems including monitoring changes in ecosystem structure and biomass estimation, carbon flux monitoring; mangroves and wetlands characterization; alpine forest characterization and delineation of tree-line ecotone, land surface deformation including measurement of deformation due to co-seismic and inter-seismic activities; landslides; land subsidence and volcanic deformation, cryosphere studies including measurements of dynamics of polar ice sheet, ice discharge to the ocean, Himalayan snow and glacier dynamics, deep and coastal ocean studies including retrieval of ocean parameters, mapping of coastal erosion and shore-line change; demarcation of high tide line (HTL) and low tide line (LTL) for coastal regulation zones (CRZ) mapping, geological studies including mapping of structural and lithological features; lineaments and paleo-channels; geo-morphological mapping, natural disaster response including mapping and monitoring of floods, forest fires, oil spills, earthquake damage and monitoring of extreme weather events such as cyclones. In addition to the above, NISAR would support various other applications such as enhanced crop monitoring, soil moisture estimation, urban area development, weather and hydrological forecasting.

NASA-ISRO Synthetic Aperture Radar (NISAR) is a Dual Frequency (L & S band) mission which will be operating in SweepSAR mode. As compared to traditional SAR imaging modes in which Swath and resolution are at trade-off, SweepSAR imaging concept can acquire data over large swath (240 Km) without compromising azimuth resolution (6m approximately). NISAR L-band & S-band sensors will be developed by JPL-NASA and ISRO respectively. NISAR science data will be downloaded at both NASA and ISRO ground stations.

SAC-ISRO will develop the SAR processor for both L & S band data to generate products in compliance with science requirements. Moreover, JPL will develop L-band SAR processor and all data products will be available to users. Distributed data processing architecture will be used for handling large volume of data resulting from moderate resolution and larger swath in SweepSAR mode. Data products will be available in multiple processing levels like raw signal products, signal processed single-look and multi-look products, ground range products and Geo-Referenced products in HDF5 & GeoTiff formats. Derived Geo-Referenced Polarimetric and Interferometric data products will also be available for dissemination to the users. A rigorous calibration exercise will be performed by acquiring data over reference targets like Amazon rain-forest & corner reflectors sites for the generation of calibrated data products. Furthermore, various science data products (for science applications) will also be derived from basic data products for operational dissemination.

The National Aeronautics and Space Administration (NASA) and the Indian Space Research Organization (ISRO) have formed a joint agency mission, NASA ISRO Synthetic Aperture Radar (NISAR) to fly in the 2020 timeframe, charged with collecting Synthetic Aperture Radar data over nearly all of earth’s land and ice, to advance science in ecosystems, solid-earth and cryospheric disciplines with global time-series maps of various phenomenon. Over a three-year mission span, NISAR will collect on the order of 24 Terabits of raw radar data per day.

Developing a plan to collect the data necessary for these three primary science disciplines and their sub-disciplines has been challenging in terms of overlapping geographic regions of interest, temporal requirements, competing modes of the radar instrument, and data-volume resources. One of the chief tools in building a plan of observations against these requirements has been a software tool developed at JPL, the Compressed Large-scale Scheduler Planner (CLASP).

CLASP intersects the temporo-geometric visibilities of a spaceborne instrument with campaigns of temporospatial maps of scientific interest, in an iterative squeaky-wheel optimization loop. While the overarching strategy for science observations has evolved through the formulation phases of this mission, so has the use of CLASP.

We’ll show how this problem space and tool has evolved over time, as well as some of the current parameter estimates for NISAR and its overall mission plan.

provide single, dual, compact and quasi-quad polarization imaging modes. Centre frequency for S-band SAR is 3200MHz with highest bandwidth of 75MHz. S-Band SAR utilizes 24 transmit receive modules (T/R Modules) to illuminate >240kms swath during transmit event and digital beam forming (DBF) on receive to reduce data rate by combining 24 receive channels and enhance SNR of the system. This paper provides details of S-band SAR system design, configuration and realization which is a challenging task since both L-band and S-band radars need to operate at same PRF and clock reference during simultaneous imaging operation. Further to this, SweepSAR technique demands PRF dithering (changing) to avoid dead gaps in the swath due to receive echo conflicting with transmit event.

The National Aeronautics and Space Administration (NASA) in the United States and the Indian Space Research Organization (ISRO) have partnered to develop an Earth-orbiting science and applications mission that exploits synthetic aperture radar to map Earth’s surface every 12 days or less. To meet demanding coverage, sampling, and accuracy requirements, the system was designed to achieve over 240 km swath at fine resolution, and using full polarimetry where needed. To address the broad range of disciplines and scientific study areas of the mission, a dual-frequency system was conceived, at L-band (24 cm wavelength) and S-band (10 cm wavelength). To achieve these observational characteristics, a reflector-feed system is considered, whereby the feed aperture elements are individually sampled to allow a scan-on-receive ("SweepSAR") capability at both L-band and S-band. The instrument leverages the expanding capabilities of on-board digital processing to enable real-time calibration and digital beamforming. This paper describes the mission characteristics, current status of the L-band Synthetic Aperture Radar (L-SAR) portion of the instrument, and the technology development efforts in the United States that are reducing risk on the key radar technologies needed to ensure proper SweepSAR operations.

The Indian Space Research Organisation (ISRO) and the National Aeronautics and Space Administration (NASA) have jointly embarked on NASA-ISRO Synthetic Aperture Radar (NISAR) operating in L-band and S-band, which will map Earth’s surface every 12 days. As a pre-cursor to the NISAR mission, ISRO is planning an airborne SAR (L&S band) which will deliver NISAR analogue data products to the science community. ISRO will develop all the hardware with the aim of adhering to system design aspects of NISAR to the maximum extent possible. It is a fully polarimetric stripmap SAR and can be operated in single, dual, compact, quasi-quad and full polarimetry modes. It has wide incidence angle coverage from 24°–77° with swath coverage from 5.5km to 15 km. Apart from simultaneous imaging operations, this system can also operate in standalone L/S SAR modes. This system is planned to operate from an aircraft platform with nominal altitude of 8000meters. Antenna for this SAR will be rigidly mounted to the aircraft, whereas, motion compensation will be implemented in the software processor to generate data products. Data products for this airborne SAR will be generated in slant & ground range azimuth dimension and geocoded in HDF5/Geotiff formats. This airborne SAR will help to prepare the Indian scientific community for optimum utilization of NISAR data. In-order to collect useful science data, airborne campaigns are planned from end of 2016 onwards.

Application of the principles of metrology for the NASA Climate Absolute Radiance and Refractivity Observatory (CLARREO) infrared high spectral resolution measurements is presented, starting with the use of a Standard International (SI) reference source on orbit, developing uncertainty traceability for intercalibration to other spaceborne sensors, and finally tracing the direct effects of radiance uncertainty on climate products originating from state parameter retrievals. The Absolute Radiance Interferometer (ARI) IR prototype employs an On-orbit Absolute Radiance Standard (OARS), developed under the NASA Instrument Incubator Program for CLARREO, for on-orbit calibration verification to better than 0.1 K 3-sigma. The OARS consists of a variable temperature, high emissivity blackbody with temperature calibration established to better than 16 mK on-orbit and provision for on-orbit emissivity monitoring. The temperature scale is established using miniature melt cells of Ga, H₂O, and Hg. Transferring the high accuracy of ARI measurements to other IR instruments, especially the high spectral resolution operational sounders (AIRS, CrIS and IASI), is an important objective of CLARREO. The mathematical approach to rigorous traceability of sampling uncertainties is explained and applied in simulations of the intercalibration process. Results show that it will be possible to make intercomparisons of better than 0.05 K 3-sigma with just 6 months of observations from a single CLARREO in true polar orbit. Finally, the effects of radiance perturbations representing realistic uncertainties (for the CrIS on Suomi NPP) on retrieved temperature and water vapor profiles are evaluated. The results demonstrate a stable, physically reasonable impact of Dual regression retrievals.

The first Joint Polar Satellite System (JPSS-1 or J1) mission is scheduled to launch in January 2017, and will be very similar to the Suomi-National Polar-orbiting Partnership (SNPP) mission. The Visible Infrared Imaging Radiometer Suite (VIIRS) on board the J1 spacecraft completed its sensor level performance testing in December 2014. VIIRS instrument is expected to provide valuable information about the Earth environment and properties on a daily basis, using a wide-swath (3,040 km) cross-track scanning radiometer. The design covers the wavelength spectrum from reflective to long-wave infrared through 22 spectral bands, from 0.412 μm to 12.01 μm, and has spatial resolutions of 370 m and 740 m at nadir for imaging and moderate bands, respectively. This paper will provide an overview of pre-launch J1 VIIRS performance testing and methodologies, describing the at-launch baseline radiometric performance as well as the metrics needed to calibrate the instrument once on orbit. Key sensor performance metrics include the sensor signal to noise ratios (SNRs), dynamic range, reflective and emissive bands calibration performance, polarization sensitivity, bands spectral performance, response-vs-scan (RVS), near field response, and stray light rejection. A set of performance metrics generated during the pre-launch testing program will be compared to the sensor requirements and to SNPP VIIRS pre-launch performance.

The Geostationary Operational Environmental Satellite R (GOES-R) series is the planned next generation of operational weather satellites for the United State’s National Oceanic and Atmospheric Administration. The first launch of the GOES-R series is planned for October 2016. The GOES-R series satellites and instruments are being developed by the National Aeronautics and Space Administration (NASA). One of the key instruments on the GOES-R series is the Advance Baseline Imager (ABI). The ABI is a multi-channel, visible through infrared, passive imaging radiometer. The ABI will provide moderate spatial and spectral resolution at high temporal and radiometric resolution to accurately monitor rapidly changing weather.

Initial on-orbit calibration and performance characterization is crucial to establishing baseline used to maintain performance throughout mission life. A series of tests has been planned to establish the post launch performance and establish the parameters needed to process the data in the Ground Processing Algorithm. The large number of detectors for each channel required to provide the needed temporal coverage presents unique challenges for accurately calibrating ABI and minimizing striping.

This paper discusses the planned tests to be performed on ABI over the six-month Post Launch Test period and the expected performance as it relates to ground tests.

The Geostationary Operational Environmental Satellite - R (GOES-R) is the first of a series of satellites to be launched, with the first launch scheduled for October 2016. The three instruments — Solar UltraViolet Imager (SUVI), Extreme ultraviolet and X-ray Irradiance Sensor (EXIS), and Space Environment In-Situ Suite (SEISS) provide the data needed as inputs for the product updates National Oceanic and Atmospheric Administration (NOAA) provides to the public. SUVI is a full-disk extreme ultraviolet imager enabling Active Region characterization, filament eruption, and flare detection. EXIS provides inputs to solar backgrounds/events impacting climate models. SEISS provides particle measurements over a wide energy-and-flux range that varies by several orders of magnitude and these data enable updates to spacecraft charge models for electrostatic discharge. EXIS and SEISS have been tested and calibrated end-to-end in ground test facilities around the United States. Due to the complexity of the SUVI design, data from component tests were used in a model to predict on-orbit performance. The ground tests and model updates provided inputs for designing the on-orbit calibration tests. A series of such tests have been planned for the Post-Launch Testing (PLT) of each of these instruments, and specific parameters have been identified that will be updated in the Ground Processing Algorithms, on-orbit parameter tables, or both. Some of SUVI and EXIS calibrations require slewing them off the Sun, while no such maneuvers are needed for SEISS. After a six-month PLT period the GOES-R is expected to be operational. The calibration details are presented in this paper.

The proto-flight test (PFT) of Infrared Scanning Radiometer (IRS) started in December 2014 to confirm the sensor performance. IRS is one of the two sensor units of Second Generation Global Imager (SGLI) on GCOM-C satellite. IRS has six optical channels from 1.1micron to 12 micron, corresponds to Short Wave Infrared (SWI) and Thermal Infrared (TIR) observation requirements of GCOM-C mission. The GCOM-C is planned for launch in 2017. This paper describes the SGLI-IRS test status.

The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) are co-operating to develop the EarthCARE satellite mission with the fundamental objective of improving the understanding of the processes involving clouds, aerosols and radiation in the Earth's atmosphere in order to include them correctly and reliably in climate and numerical weather prediction models.

The satellite will be placed in a Sun-Synchronous Orbit at about 400 Km altitude and14h00 mean local solar time. The payload consisting of a High Spectral Resolution UV Atmospheric LIDar (ATLID), a 94GHz Cloud Profiling Radar (CPR) with Doppler capability, a Multi-Spectral Imager (MSI) and a Broad-Band Radiometer will provide information on cloud and aerosol vertical structure of the atmosphere along the satellite track as well as information about the horizontal structures of clouds and radiant flux from sub-satellite cells.

The presentation will cover the configuration of the satellite with its four instruments, the mission implementation approach, an overview of the ground segment and the overall mission development status.

The "Advanced optical satellite" (tentative name) is a follow-on mission from ALOS. Mission objectives of the advanced optical satellite is to build upon the existing advanced techniques for global land observation using optical sensors, as well as to promote data utilization for social needs. Wide swath and high resolution optical imager onboard the advanced optical satellite will extend the capabilities of earlier ALOS missions. The optical imager will be able to collect high-resolution (< 1 m) and wide-swath (70 km) images with high geo-location accuracy. This paper introduces a conceptual design of the advanced optical satellite.

The Second-generation Global Imager (SGLI) is a mission instrument on the Global Change Observation Mission-Climate (GCOM-C) satellite. The SGLI includes two radiometers, the Visible and Near Infrared Radiometer (VNR) and Infrared Scanning Radiometer (IRS). The VNR is a multi-band optical imaging radiometer observing at wavelength range from 380 nm to 868.5 nm, including non-polarization and polarization observation. The test of the instruments consisting of VNR-SRU (Scanning Radiometer Unit) PFM (Proto-Flight model) has been finished, and the VNR-SRU PFM is under the phase of assembly and test. This paper describes the test result of the VNR-SRU PFM.

The Snow and Water Imaging Spectrometer (SWIS) is a fast, high-uniformity, low-polarization sensitivity imaging spectrometer and telescope system designed for integration on a 6U CubeSat platform. Operating in the 350-1700 nm spectral region with 5.7 nm sampling, SWIS is capable of simultaneously addressing the demanding needs of coastal ocean science and snow and ice monitoring. New key technologies that facilitate the development of this instrument include a linear variable anti-reflection (LVAR) detector coating for stray light management, and a single drive on-board calibration mechanism utilizing a transmissive diffuser for solar calibration. We provide an overview of the SWIS instrument design, spacecraft configuration design, and potential science missions.

Hyperspectral imaging spectrometer systems are increasingly being used in the field of remote sensing for variety of civilian and military applications. The ability of such instruments in discriminating finer spectral features along with improved spatial and radiometric performance have made such instruments a powerful tool in the field of remote sensing. Design and development of spaceborne hyper spectral imaging spectrometers poses lot of technological challenges in terms of optics, dispersion element, detectors, electronics and mechanical systems.

The main factors that define the type of detectors are the spectral region, SNR, dynamic range, pixel size, number of pixels, frame rate, operating temperature etc. Detectors with higher quantum efficiency and higher well depth are the preferred choice for such applications. CCD based Si detectors serves the requirement of high well depth for VNIR band spectrometers but suffers from smear. Smear can be controlled by using CMOS detectors. Si CMOS detectors with large format arrays are available. These detectors generally have smaller pitch and low well depth. Binning technique can be used with available CMOS detectors to meet the large swath, higher resolution and high SNR requirements. Availability of larger dwell time of satellite can be used to bin multiple frames to increase the signal collection even with lesser well depth detectors and ultimately increase the SNR. Lab measurements reveal that SNR improvement by frame binning is more in comparison to pixel binning. Effect of pixel binning as compared to the frame binning will be discussed and degradation of SNR as compared to theoretical value for pixel binning will be analyzed.

Significantly reducing weather and climate prediction uncertainty requires global observations with substantially higher information content than present observations provide. While GPS occultations have provided a major advance, GPS observations of the atmosphere are limited by wavelengths chosen specifically to minimize interaction with the atmosphere. Significantly more information can be obtained via satellite to satellite occultations made at wavelengths chosen specifically to characterize the atmosphere. Here we describe such a system that will probe cm- and mmwavelength water vapor absorption lines called the Active Temperature, Ozone and Moisture Microwave Spectrometer (ATOMMS). Profiling both the speed and absorption of light enables ATOMMS to profile temperature, pressure and humidity simultaneously, which GPS occultations cannot do, as well as profile clouds and turbulence. We summarize the ATOMMS concept and its theoretical performance. We describe field measurements made with a prototype ATOMMS instrument and several important capabilities demonstrated with those ground based measurements including retrieving temporal variations in path-averaged water vapor to 1%, in clear, cloudy and rainy conditions, up to optical depths of 17, remotely sensing turbulence and determining rain rates. We conclude with a vision of a future ATOMMS low Earth orbiting satellite constellation designed to take advantage of synergies between observational needs for weather and climate, ATOMMS unprecedented orbital remote sensing capabilities and recent cubesat technological innovations that enable a constellation of dozens of very small spacecraft to achieve many critical, but as yet unfulfilled, monitoring and forecasting needs.

This paper discusses about the design &developmental of Ground Penetrating Radar (GPR), various scientific and commercial applications of GPR along with the testing and results of GPR at Antarctica for Ice thickness measurement. GPR instruments are categorised as per their frequency of operation, which is inversely proportional to the depth of penetration. GPRs are also categorized as per method of operation which is time-domain or frequency-domain. Indian market is presently procuring GPRs from only foreign suppliers. Space Applications Centre (SAC) had taken up GPR as R&D Technological development with a view to benchmark the technology which may be transferred to local industry for mass production of instrument at a relatively cheaper cost (~20 times cheaper). Hence, this instrument presents a viable indigenous alternative. Also, the design and configuration was targeted for terrestrial as well as future interplanetary (Lander/Rover) missions of ISRO to map subsurface features. The developed GPR has a very large bandwidth (100%, i.e. bandwidth of 500MHz with centre-frequency of 500MHz) and high dynamic range along with the advantage of being highly portable (<10kg). The system was configured as a Stepped-Frequency-Continuous-Wave (SFCW) GPR which is a frequency domain GPR with the aim to increase the detection capabilities with respect to current systems. In order to achieve this goal, innovative electronic equipment have been designed and developed. Three prototypes were developed and two of them have been delivered for Indian Scientific Expedition to Antarctica (ISEA) in 2013 and 2014-15, respectively and promising results have been obtained. The results from the same closely compare with that from commercial GPR too.

The large number of missions associated with ESA’s Copernicus program has necessitated several new image sensor designs for earth observation (or living planet) applications as each instrument needs to be highly optimized. Whilst the majority of these sensors have utilised CCD technology, the use of CMOS is starting to increase.

New CCD designs and technology trends for hyperspectral applications such as Sentinel 4, Sentinel 5, Sentinel 5 precursor (TropOMI), Flex and 3MI are described. In these the sensor design has been optimized to provide highest possible signal levels with lowest possible noise in combination with higher frame rates and reduced image smear.

CMOS sensors for MTG (Meteosat Third Generation) and METImage are then described. Both use extremely large pixels, up to 250μm square, at high line rates. Radiation test data and key performance measurements are shown for MTG and for a test device that has been made for METImage. Finally, newer developments including back-illumination and means for achieving a TDI function in standard-processed CMOS are briefly described.

Silicon based charge coupled device (CCD) performances have improved immensely over the years. Scientific community across the globe target challenging remote sensing applications with CCD as optical imaging detector. Over the years, both pixel count (from few hundreds to few tens of thousands) and line readout rate (from few kHz to few tens of kHz) have increased considerably. Pixels are readout using a large number of output ports driven up to few tens of MHz Moreover, for multi-spectral applications, same Si die contains multiple arrays sharing input stimuli. This is usually done to optimize package pin count. Si die as well as package level layout of clock and bias lines become critical for closely spaced multi-array devices. The inter-array separation may go down to few hundreds of microns when filter coating is laid on top of the die. Die level layout becomes quite critical for devices with such architecture. The inter-array (consecutive arrays) separation is optimized to reduce optical coupling / stray light in devices integrated multi-band strip filter. Layout constraints along with shared bias/clock lines are known to produce electrical cross-talk or coupling. Effect of this (within one array or between two arrays) cross-talk is more pronounced in systems having low noise floor. Video signal dependent coupling in a multi-port system becomes quite complex and leads to a relatively noisier system (post correction). The paper presents results of simulations and tests (pre and post correction) addressing this type of electrical coupling. The paper presents cause, impact and possible remedial measures to minimize such coupling in a multi-array, multi-port TDI CCD from 1.3% to below 0.06%.

The paper presents the scheme for improving the image contrast in the remote sensing images and highlights the novelty in hardware & software design in the test system developed for measuring image contrast function. Modulation transfer function (MTF) is the most critical quality element of the high-resolution imaging payloads for earth observation consisting of TDI-CCD (Time Delayed Integration Charge Coupled Device) image. From the mathematical model for MTF Smear MTF of 65% (35% degradation) is observed. Then a operating method for TDI-CCD is developed, using which 96% of Motion Smear MTF will occur within the imaging operation. As a major part of the validation, indigenously designed and developed a test system for measuring the dynamic MTF of TDI Sensors which consists of the optical scanning system, TDI-CCD camera drive & video processing electronics, thermal control system and telecentric uniform illumination system. The experimental results confirm that image quality improvement can be achieved by this method. This method is now implemented in the flight model hardware of the remote sensing payload.

This paper discusses the design, development, characterization and qualification aspects of large format Infrared Focal Plane Arrays (IRFPA) required for panchromatic, multi-, hyper- and ultra-spectral imaging applications from a space-borne imager. Detection of feeble radiant flux from the intended target in narrow spectral bands requires a highly sensitive low noise sensor array with high well capacity. For this the photodiode arrays responsive in desired spectral band are grown using different growth techniques and flip-chip bonded with a suitable Si Read-out ICs (ROICs) for signal conditioning. IR detectors require cryogenic cooling to achieve background limited performance. Although passive radiative cooling is always the preferred choice of cooling in space, it is not suitable for cooling IRFPAs due to high thermal loads. To facilitate characterization of IRFPAs and cool them to desired cryogenic temperature, an Integrated Detector Dewar Cooler Assembly (IDDCA) is essential where the detector array sits over the cold tip of an active cooler and the detector cooler assembly is vacuum sealed in a thermally isolated Dewar. A cold shield above the sensor array inside the Dewar restricts its field-of-view and a cold filter fine tunes its spectral response. In this paper, various constituents of an IRFPA like sensor array materials, growth techniques, ROICs, filters, cold shields, cooling techniques etc., their types and selection criteria for different applications are discussed in detail. Design aspects of IRFPA characterization test bench, challenges involved in radiometric and spectral characterization and space qualification of such IDDCA based IRFPAs are also discussed.

Weather satellite instruments require detectors with a variety of wavelengths ranging from the visible to VLWIR. One of the remote sensing applications is the geostationary GOES-ABI imager covering wavelengths from the 450 to 490 nm band through the 13.0 to 13.6 μm band. There are a total of 16 spectral bands covered. The Cross-track infrared Sounder (CrIS) is a Polar Orbiting interferometric sensor that measures earth radiances at high spectral resolution, using the data to provide pressure, temperature and moisture profiles of the atmosphere. The pressure, temperature and moisture sounding data are used in weather prediction models that track storms, predict levels of precipitation etc. The CrIS instrument contains SWIR (λ_c ∼ 5 μm at 98K), MWIR (λ_c ∼ 9 μm at 98K) and LWIRs (λ_c ∼ 15.5 μm at 81K) bands in three Focal Plane Array Assemblies (FPAAs).

GOES-ABI contains three focal plane modules (FPMs), (i) a visible-near infrared module consisting of three visible and three near infrared channels, (ii) a MWIR module comprised of five channels from 3.9 μm to 8.6 μm and (iii) a 9.6 μm to 13.3 μm, five-channel LWIR module. The VNIR FPM operates at 205 K, and the MWIR and LWIR FPMs operate at 60 K. Each spectral channel has a redundant array built into a single detector chip. Switching is thus permitted from the primary selected array in each channel to the redundant array, given any degradation in performance of the primary array during the course of the mission. Silicon p-i-n detectors are used for the 0.47 μm to 0.86 μm channels. The thirteen channels above 1 μm are fabricated in various compositions of Hg_1-xCd_xTe, and in this particular case using two different detector architectures. The 1.38 μm to 9.61 μm channels are all fabricated in Hg_1-xCd_xTe grown by Liquid Phase Epitaxy (LPE) using the HDVIP detector architecture. Molecular beam epitaxy (MBE)-grown Hg_1-xCd_xTe material are used for the LWIR 10.35 μm to 13.3 μm channels fabricated in Double layer planar heterostructure (DLPH) detectors. This is the same architecture used for the CrIS detectors.

CrIS detectors are 850 μm diameter detectors with each FPAA consisting of nine photovoltaic detectors arranged in a 3 x 3 pattern. Each detector has an accompanying cold preamplifier. SWIR and MWIR FPAAs operate at 98 K and the LWIR FPAA at 81 K, permitting the use of passive radiators to cool the detectors. D* requirements at peak wavelength are ≥ 5.0E+10 Jones for LWIR, ≥ 9.3E+10 Jones for MWIR and ≥ 3.0E+11 Jones for SWIR. All FPAAs exceeded the D* requirements. Measured mean values for the nine photodiodes in each of the LWIR, MWIR and SWIR FPAAs are D* = 5.3 x 10¹⁰ cm-Hz^1/2/W at 14.0 μm, 1.0 x 10¹¹ cm-Hz^1/2/W at 8.0 μm and 3.1 x 10¹¹ cm-Hz^1/2/W at 4.64 μm.

Cryogenically cooled HgCdTe (MCT) quantum detectors are unequalled for applications requiring high imaging as well as high radiometric performance in the infrared spectral range. Compared with other technologies, they provide several advantages, such as the highest quantum efficiency, lower power dissipation compared to photoconductive devices, and fast response times, hence outperforming micro-bolometer arrays. AIM will present its latest results on n-on-p as well as p-on-n low dark current planar MCT photodiode focal plane detector arrays at cut-off wavelengths >11 μm at 80 K. Dark current densities below the Rule’07 have been demonstrated for n-on-p devices. Slightly higher dark current densities and excellent cosmetics with very low cluster and point defect densities have been demonstrated for p-on-n devices.

IASI (Infrared Atmospheric Sounding Interferometer), developed by CNES and launched since 2006 on the Metop satellites, is established as a major source of data for atmospheric science and weather prediction. The next generation - IASI NG - is a French national contribution to the Eumetsat Polar System Second Generation on board of the Metop second generation satellites and is under development by Airbus Defence and Space for CNES. The mission aim is to achieve twice the performance of the original IASI instrument in terms of sensitivity and spectral resolution. In turn, this places very demanding requirements on the infrared detectors for the new instrument. Selex ES in Southampton has been selected for the development of the infrared detector set for the IASI-NG instruments. The wide spectral range, 3.6 to 15.5 microns, is covered in four bands, each served by a dedicated detector design, with a common 4 x 4 array format of 1.3 mm square macropixels. Three of the bands up to 8.7 microns employ photovoltaic MCT (mercury cadmium telluride) technology and the very long wave band employs photoconductive MCT, in common with the approach taken between Airbus and Selex ES for the SEVIRI instrument on Second Generation Meteosat. For the photovoltaic detectors, the MCT crystal growth of heterojunction photodiodes is by the MOVPE technique (metal organic vapour phase epitaxy). Novel approaches have been taken to hardening the photovoltaic macropixels against localised crystal defects, and integrating transimpedance amplifiers for each macropixel into a full-custom silicon read out chip, which incorporates radiation hard design.

The space weather instruments (Space Environment In-Situ Suite – SEISS) on the soon to be launched, NOAA GOES-R series spacecraft offer significant space weather measurement performance advances over the previous GOES N-P series instruments. The specifications require that the instruments ensure proper operation under the most stressful high flux conditions corresponding to the largest solar particle event expected during the program, while maintaining high sensitivity at low flux levels. Since the performance of remote sensing instruments is sensitive to local space weather conditions, the SEISS data will be of be of use to a broad community of users. The SEISS suite comprises five individual sensors and a data processing unit: Magnetospheric Particle Sensor-Low (0.03–30 keV electrons and ions), Magnetospheric Particle Sensor-High (0.05–4 MeV electrons, 0.08–12 MeV protons), two Solar And Galactic Proton Sensors (1 to >500 MeV protons), and the Energetic Heavy ion Sensor (10-200 MeV for H, H to Fe with single element resolution). We present comparisons between the enhanced GOES-R instruments and the current GOES space weather measurement capabilities. We provide an overview of the sensor configurations and performance. Results of extensive sensor modeling with GEANT, FLUKA and SIMION are compared with calibration data measured over nearly the entire energy range of the instruments. Combination of the calibration results and model are used to calculate the geometric factors of the various energy channels. The calibrated geometric factors and typical and extreme space weather environments are used to calculate the expected on-orbit performance.

The GOES-R Flight Project has developed an Image Navigation and Registration (INR) Performance Assessment Tool Set (IPATS) for measuring Advanced Baseline Imager (ABI) and Geostationary Lightning Mapper (GLM) INR performance metrics in the post-launch period for performance evaluation and long term monitoring. For ABI, these metrics are the 3-sigma errors in navigation (NAV), channel-to-channel registration (CCR), frame-to-frame registration (FFR), swath-to-swath registration (SSR), and within frame registration (WIFR) for the Level 1B image products. For GLM, the single metric of interest is the 3-sigma error in the navigation of background images (GLM NAV) used by the system to navigate lightning strikes. 3-sigma errors are estimates of the 99. 73^rd percentile of the errors accumulated over a 24 hour data collection period. IPATS utilizes a modular algorithmic design to allow user selection of data processing sequences optimized for generation of each INR metric. This novel modular approach minimizes duplication of common processing elements, thereby maximizing code efficiency and speed. Fast processing is essential given the large number of sub-image registrations required to generate INR metrics for the many images produced over a 24 hour evaluation period. Another aspect of the IPATS design that vastly reduces execution time is the off-line propagation of Landsat based truth images to the fixed grid coordinates system for each of the three GOES-R satellite locations, operational East and West and initial checkout locations. This paper describes the algorithmic design and implementation of IPATS and provides preliminary test results.

Radar Imaging Satellite (RISAT-1) payload system is configured to perform self-calibration of transmit and receive paths before and after imaging sessions through a special instrument calibration technique. Instrument calibration architecture of RISAT-1 supported ground verification and validation of payload including active array antenna. During on-ground validation of 126 beams of active array antenna which needed precise calibration of boresight pointing, a unique method called "collimation coefficient error estimation" was utilized. This method of antenna calibration was supported by special hardware and software calibration architecture of RISAT-1. This paper concentrates on RISAT-1 hardware and software architecture which supports in-orbit and on-ground instrument calibration. Efforts are also put here to highlight use of special calibration scheme of RISAT-1 instrument to evaluate system response during ground verification and validation.

The MODIS has successfully operated on-board the NASA’s EOS Terra and Aqua spacecraft for more than 16 and 14 years, respectively. MODIS instrument was designed with stringent calibration requirements and comprehensive on-board calibration capability. In the reflective solar spectral region, Aqua MODIS has performed better than Terra MODIS and, therefore, has been chosen by the Global Space-based Inter- Calibration System (GSICS) operational community as the calibration reference sensor in cross-sensor calibration and calibration inter-comparisons. For the same reason, it has also been used by a number of earth-observing sensors as their calibration reference. Considering that Aqua MODIS has already operated for nearly 14 years, it is essential to transfer its calibration to a follow-on reference sensor with a similar calibration capability and stable performance. The VIIRS is a follow-on instrument to MODIS and has many similar design features as MODIS, including their on-board calibrators (OBC). As a result, VIIRS is an ideal candidate to replace MODIS to serve as the future GSICS reference sensor. Since launch, the S-NPP VIIRS has already operated for more than 4 years and its overall performance has been extensively characterized and demonstrated to meet its overall design requirements. This paper provides an overview of Aqua MODIS and S-NPP VIIRS reflective solar bands (RSB) calibration methodologies and strategies, traceability, and their on-orbit performance. It describes and illustrates different methods and approaches that can be used to facilitate the calibration reference transfer, including the use of desert and Antarctic sites, deep convective clouds (DCC), and the lunar observations.

Moderate Resolution Imaging Spectroradiometer (MODIS) is the keystone instrument for NASA’s EOS Terra and Aqua missions, designed to extend and improve heritage sensor measurements and data records of the land, oceans and atmosphere. The reflective solar bands (RSB) of MODIS covering wavelengths from 0.41 μm to 2.2 μm, are calibrated on-orbit using a solar diffuser (SD), with its on-orbit bi-directional reflectance factor (BRF) changes tracked using a solar diffuser stability monitor (SDSM). MODIS is a scanning radiometer using a two-sided paddle-wheel mirror to collect earth view (EV) data over a range of ±55° off instrument nadir. In addition to the solar calibration provided by the SD and SDSM system, lunar observations at nearly constant phase angles are regularly scheduled to monitor the RSB calibration stability. For both Terra and Aqua MODIS, the SD and lunar observations are used together to track the on-orbit changes of RSB response versus scan angle (RVS) as the SD and SV port are viewed at different angles of incidence (AOI) on the scan mirror. The MODIS Level 1B (L1B) Collection 6 (C6) algorithm incorporated several enhancements over its predecessor Collection 5 (C5) algorithm. A notable improvement was the use of the earth-view (EV) response trends from pseudo-invariant desert targets to characterize the on-orbit RVS for select RSB (Terra bands 1-4, 8, 9 and Aqua bands 8, 9) and the time, AOI, and wavelength-dependent uncertainty. The MODIS Characterization Support Team (MCST) has been maintaining and enhancing the C6 algorithm since its first update in November, 2011 for Aqua MODIS, and February, 2012 for Terra MODIS. Several calibration improvements have been incorporated that include extending the EV-based RVS approach to other RSB, additional correction for SD degradation at SWIR wavelengths, and alternative approaches for on-orbit RVS characterization. In addition to the on-orbit performance of the MODIS RSB, this paper also discusses in detail the recent calibration improvements implemented in the MODIS L1B C6.

Since launch, both Terra and Aqua MODIS instruments have continued to operate and make measurements of the earth’s top of atmospheric (TOA) radiances and reflectance. MODIS collects data in 36 spectral bands covering wavelengths from 0.41 to 14.4 μm. These spectral bands and detectors are located on four focal plane assemblies (FPAs). MODIS on-board calibrators (OBC) include a spectro-radiometric calibration assembly (SRCA), which was designed to characterize and monitor sensor spatial and spectral performance, such as on-orbit changes in the band-to-band registration (BBR), modulation transfer function (MTF), spectral band center wavelengths (CW) and bandwidths (BW). In this paper, we provide a status update of MODIS spatial and spectral characterization and performance, following a brief description of SRCA functions and on-orbit calibration activities. Sensor spatial and spectral performance parameters derived from SRCA measurements are introduced and discussed. Results show that on-orbit spatial performance has been very stable for both Terra and Aqua MODIS instruments. The large BBR shifts in Aqua MODIS, an issue identified pre-launch, have remained the same over its entire mission. On-orbit changes in CW and BW are less than 0.5 nm and 1 nm, respectively, for most VIS/NIR spectral bands of both instruments.

It has been nearly four years that the S-NPP was launched. In an effort to improve the VIIRS calibration, VIIRS has undergone a number of major look up table updates during this period. RSB bands such as M1 through M3 suggested higher solar diffuser degradation rate. Similarly, for higher wavelengths, even though the solar diffuser degradation is much smaller and even negligible for SWIR bands, bands such as M7 suffer from major degradation due to RTA throughput degradation. Even though the solar diffuser and mirror degradation is well characterized, the data quality needs to be independently validated to ensure that data are well within the specification. We have used on-orbit calibration/validation techniques such as extended SNOs to estimate the bias of these bands and quantify the radiometric performance since launch. Assuming MODIS as a standard reference, intercomparison was performed to analyze the VIIRS radiometric performance. It was observed that some of the VIIRS bands such as M5 and M7 suggest bias on the order of 1.5% or more for most of the time period since early launch. VIIRS bias trends keep changing over time which can be mainly correlated to calibration updates and instrument anomalies. Results on VIIRS on-orbit calibration performance and its bias since early launch will be presented during meeting to help users better understand the data quality and its impacts on broader scientific research and applications.

In this work, vicarious calibration coefficients for all the four bands (green, red, NIR and SWIR) of Resourcesat-2 AWiFS sensor for four dates during Dec 2013-Nov 2014 and for seven bands (blue, green, red, NIR, SWIR1, SWIR2 and PAN) of OLI sensor onboard Landsat-8 for six dates during Dec 2013-Feb 2015 were estimated using field measured reflectance and measured atmospheric parameters during sensor image acquisition over Rann of Kutch site in Gujarat. The top of atmosphere (TOA) at-satellite radiances for all the bands were simulated using 6S radiative transfer code with field measured reflectance, synchronous atmospheric measurements and respective sensor’s spectral response functions as an input. These predicted spectral radiances were compared with the radiances from the respective sensor’s image in the respective band over the calibration site. Cross-calibration between the sensors AWiFS and OLI was also attempted using near-simultaneous same day image acquisition. Effect of spectral band adjustment factor was also studied with OLI sensor taken as reference sensor. Results show that the variation in average estimated radiance ratio for the AWiFS sensor was found to be within 10% for all the bands, whereas, for OLI sensor, the variation was found to be within 6% for all the bands except green and SWIR2 for which the variation was 8% and 11% respectively higher than the 5% uncertainty of the OLI sensor specification for TOA spectral radiance. At the 1σ level, red, NIR, SWIR1 and Panchromatic bands of OLI sensor showed close agreement between sensor-measured and vicarious TOA radiance resulting no change in calibration coefficient and hence indicating no sensor degradation. Two sets of near-simultaneous SBAFs were derived from respective ground measured target reflectance profiles and applied to the AWiFS and it was observed that overall, SBAF compensation provides a significant improvement in sensor agreement. The reduction in the difference between AWiFS and OLI measured TOA reflectance was found to be within 1% for green band and within 0.5% for Red band, whereas, maximum difference was observed for NIR band (within 3.4%) after applying SBAF correction.

Radiometric performances of earth observation satellite/sensors vary from ground pre-launch calibration campaign to post launch period extended to lifetime of the satellite due to launching vibrations. Therefore calibration is carried out worldwide through various methods throughout satellite lifetime. In India Indian Space Research Organization (ISRO) calibrates the sensor of Resourcesat-2 satellite by vicarious method. One of these vicarious calibration methods is the reflectance-based approach that is applied in this study for radiometric calibration of sensors on-board Resouresat-2 satellite. The results of ground-based measurement of atmospheric conditions and surface reflectance are made at Bap, Rajasthan Calibration/Validation (Cal/Val) site. Cal/Val observations at site were carried out with hyper-spectral Spectroradiometer covering spectral range of 350nm- 2500nm for radiometric characterization of the site. The Sunphotometer/Ozonometer for measuring the atmospheric parameters has also been used. The calibrated radiance is converted to absolute at-sensor spectral reflectance and Top-Of-Atmosphere (TOA) radiance. TOA radiance was computed using radiative transfer model ‘Second simulation of the satellite signal in the solar spectrum’ (6S), which can accurately simulate the problems introduced by the presence of the atmosphere along the path from Sun to target (surface) to Sensor. The methodology for band averaged reflectance retrieval and spectral reflectance fitting process are described. Then the spectral reflectance and atmospheric parameters are put into 6S code to predict TOA radiance which compare with Resourcesat-2 radiance. Spectral signature and its reflectance ratio indicate the uniformity of the site. Thus the study proves that the selected site is suitable for vicarious calibration of sensor of Resourcesat-2. Further the study demonstrates the procedure for similar exercise for site selection for Cal/Val analysis of other satellite over India region.

The absolute radiometric calibration of the reflective solar bands (RSBs) of Aqua- and Terra-MODIS is performed using on-board calibrators. A solar diffuser (SD) panel along with a solar diffuser stability monitor (SDSM) system, which tracks the degradation of the SD over time, provides the baseline for calibrating the MODIS sensors. MODIS also views the moon and deep space through its space view (SV) port for lunar-based calibration and computing the background, respectively. The MODIS instrument views the Earth’s surface using a two-sided scan mirror, whose reflectance is a function of the angle of incidence (AOI) and is described by response versus scan-angle (RVS). The RVS for both MODIS instruments was characterized prior to launch. MODIS also views the SD and the moon at two different AOIs. There is sufficient evidence that the RVS is changing on orbit over time and as a function of wavelength. The SD and lunar observation scans can only track the RVS variation at two AOIs. Consequently, the MODIS Characterization Support Team (MCST) developed enhanced approaches that supplement the onboard calibrator measurements with responses from the pseudo-invariant desert sites. This approach has been implemented in Level 1B (L1B) Collection 6 (C6) for select short-wavelength bands. This paper presents an alternative approach of characterizing the mirror RVS to derive the time-dependent RVS correction factors for MODIS RSBs using tropical deep convective cloud (DCC) targets. An initial assessment of the DCC response from Aqua-MODIS band 1 C6 data indicates evidence of RVS artifacts, which are not uniform across the scans and are more prevalent at the beginning of the earth-view scan.

The push-broom sensors in bands meant to study oceans, in general suffer from residual non uniformity even after radiometric correction. The in-orbit data from OCM-2 shows pronounced striping in lower bands. There have been many attempts and different approaches to solve the problem using image data itself. The success or lack of it of each algorithm lies on the quality of the uniform region identified. In this paper, an image based destriping algorithm is presented with constraints being derived from Ground Calibration exercise. The basis of the methodology is determination of pixel to pixel non-uniformity through uniform segments identified and collected from large number of images, covering the dynamic range of the sensor. The results show the effectiveness of the algorithm over different targets. The performance is qualitatively evaluated by visual inspection and quantitatively measured by two parameters.

This paper presents an overview of the estimation of noise, techniques for noise removal in Single Look Complex (SLC) as well as hybrid polarimetry decomposed images and the effects of noise removal in SAR images, using RISAT-1 data. Thermal noise affects the signal to noise ratio as well as radiometry of the SAR images. Different approaches adopted for estimating the thermal noise using onboard noise measurements and from the noise equivalent area of the images like calm reservoirs, lakes, etc., for RISAT-1 SAR are discussed. Subsequent to noise removal, its effect on minimum detectable noise and SNR of the images is addressed. Traditional noise removal methods affect the phase of the data, which in turn affect advanced SAR applications. A brief overview of the hybrid polarimetry configuration of RISAT-1 SAR, one of the emerging trends in polarimetry domain, is given and the effect of using noise removed single look complex (SLC) images for polarimetry decomposition is brought out. Thereby, a new technique for thermal noise removal in polarimetry decomposed data is presented.

There is a trend of SAR imaging at low frequencies (VHF/UHF, L-band) and wide bandwidth, for penetration into foliage for high resolution applications. The propagation of spaceborne radar signals operating at L-band frequency or below can be seriously affected by the ionosphere. While these effects are negligible at X-band, Faraday Rotation and the frequency-dependent path delays can become seriously problematic at L-band. Range delay, interferometric phase bias, range defocussing and Faraday rotation are the most prominent ones. Due to ionospheric effects, blind use of a generic matched filter causes inaccuracies when correlating the received signal with transmitted replica. In this paper we study the effects of frequency dependent path delays in L-band SAR chirp signal due to ionospheric electron density. Also a method to correct ionospheric anomalies without the knowledge of electron content level in a single SAR acquisition is proposed.

Cryospheric surface feature classification is one of the widely used applications in the field of polar remote sensing. Precise surface feature maps derived from remotely sensed imageries are the major requirement for many geoscientific applications in polar regions. The present study explores the capabilities of C-band dual polarimetric (HH & HV) SAR imagery from Indian Radar Imaging Satellite (RISAT-1) for land cryospheric surface feature mapping. The study areas selected for the present task were Larsemann Hills and Schirmacher Oasis, East Antarctica. RISAT-1 Fine Resolution STRIPMAP (FRS-1) mode data with 3-m spatial resolution was used in the present research attempt. In order to provide additional context to the amount of information in dual polarized RISAT-1 SAR data, a band HH+HV was introduced to make use of the original two polarizations. In addition to the data calibration, transformed divergence (TD) procedure was performed for class separability analysis to evaluate the quality of the statistics before image classification. For most of the class pairs the TD values were comparable, which indicated that the classes have good separability. Fuzzy and Artificial Neural Network classifiers were implemented and accuracy was checked. Nonparametric classifier Support Vector Machine (SVM) was also used to classify RISAT-1 data with an optimized polarization combination into three land-cover classes consisting of sea ice/snow/ice, rocks/landmass, and lakes/waterbodies. This study demonstrates that C-band FRS1 image mode data from the RISAT-1 mission can be exploited to identify, map and monitor land cover features in the polar regions, even during dark winter period. For better landcover classification and analysis, hybrid polarimetric data (cFRS-1 mode) from RISAT-1, which incorporates phase information, unlike the dual-pol linear (HH, HV) can be used for obtaining better polarization signatures.

Synthetic Aperture Radar (SAR) is one of the most recent imaging technology to study the forest parameters. The invincible characteristics of microwave acquisition in cloudy regions and night imaging makes it a powerful tool to study dense forest regions. A coherent combination of radar polarimetry and interferometry (PolInSAR) enhances the accuracy of retrieved biophysical parameters. This paper attempts to address the issue of estimation of forest structural information caused due to instability of radar platforms through simulation of SAR image. The Terai Central Forest region situated at Haldwani area in Uttarakhand state of India was chosen as the study area. The system characteristics of PolInSAR dataset of Radarsat-2 SAR sensor was used for simulation process. Geometric and system specifications like platform altitude, center frequency, mean incidence angle, azimuth and range resolution were taken from metadata. From the field data it was observed that average tree height and forest stand density were 25 m and 300 stems/ha respectively. The obtained simulated results were compared with the sensor acquired master and slave intensity images. It was analyzed that for co-polarized horizontal component (HH), the mean values of simulated and real master image had a difference of 0.3645 with standard deviation of 0.63. Cross-polarized (HV) channel showed better results with mean difference of 0.06 and standard deviation of 0.1 while co-polarized vertical component (VV) did not show similar values. In case of HV polarization, mean variation between simulated and real slave images was found to be the least. Since cross-polarized channel is more sensitive to vegetation feature therefore better simulated results were obtained for this channel. Further the simulated images were processed using PolInSAR inversion modelling approach using three different techniques DEM differencing, Coherence Amplitude Inversion and Random Volume over Ground Inversion. DEM differencing technique calculates tree height by generating Digital Elevation Models (DEM) from interferograms in different polarizations and differences in DEM estimates the vegetation height. In CAI technique the phase of coherence is ignored and volume scattering is mainly considered for estimating height. The RVoG model considers both vegetation layer and ground interactions. In this model, the vertical distribution of scatterers do not change with the change in polarization. It was found that with vertical wavenumber values between 0.2113 to .2249 rad/m for mean incidence angle 34.226 degrees the range of tree height achieved by Coherence Amplitude Inversion and RVoG was better among the three inversion techniques.

The LISS-IV sensor aboard Resourcesat-2 is a modern relatively high resolution multispectral sensor having immense potential for generation of good quality land use land cover maps. It generates data in high (10-bit) radiometric resolution and 5.8 m spatial resolution and has three bands in the visible-near infrared region. This is of particular importance to global community as the data are provided at highly competitive prices. However, no literature describing the atmospheric correction of Resourcesat-2-LISS-IV data could be found. Further, without atmospheric correction full radiometric potential of any remote sensing data remains underutilized. The FLAASH and QUAC module of ENVI software are highly used by researchers for atmospheric correction of popular remote sensing data such as Landsat, SPOT, IKONOS, LISS-I, III etc. This article outlines a methodology for atmospheric correction of Resourcesat-2-LISS-IV data. Also, a comparison of reflectance from different atmospheric correction modules (FLAASH and QUAC) with TOA and standard data has been made to determine the best suitable method for reflectance estimation for this sensor.

The Advanced Wide Field Sensor (AWiFS) camera caters to high temporal resolution requirement of Resourcesat-2A mission with repeativity of 5 days. The AWiFS camera consists of four spectral bands, three in the visible and near IR and one in the short wave infrared. The imaging concept in VNIR bands is based on push broom scanning that uses linear array silicon charge coupled device (CCD) based Focal Plane Array (FPA). On-Board Calibration unit for these CCD based FPAs is used to monitor any degradation in FPA during entire mission life. Four LEDs are operated in constant current mode and 16 different light intensity levels are generated by electronically changing exposure of CCD throughout the calibration cycle. This paper describes experimental setup and characterization results of various flight model visible LEDs (λ_P=650nm) for development of On-Board Calibration unit of Advanced Wide Field Sensor (AWiFS) camera of RESOURCESAT-2A. Various LED configurations have been studied to meet dynamic range coverage of 6000 pixels silicon CCD based focal plane array from 20% to 60% of saturation during night pass of the satellite to identify degradation of detector elements. The paper also explains comparison of simulation and experimental results of CCD output profile at different LED combinations in constant current mode.

MODerate resolution Imaging Spectroradiometer (MODIS), a leading heritage sensor in the fleet of Earth Observing System for the National Aeronautics and Space Administration (NASA) is in space orbit on two spacecrafts. They are the Terra (T) and Aqua (A) platforms. Both instruments have successfully continued to operate beyond the 6 year design life time, with the T-MODIS currently functional beyond 15 years and the A-MODIS operating beyond 13 years respectively. The MODIS sensor characteristics include a spectral coverage from 0.41 μm – 14.4 μm, of which wavelengths ranging from 3.7 μm – 14. 4 μm cover the thermal infrared region also referred to as the Thermal Emissive Bands (TEBs). The TEBs is calibrated using a v-grooved BlackBody (BB) whose temperature measurements are traceable to the National Institute of Standards and Technology temperature scales. The TEBs calibration based on the onboard BB is extremely important for its high radiometric fidelity. In this paper, we provide a complete characterization of the lifetime instrument performance of both MODIS instruments in terms of the sensor gain, the Noise Equivalent difference Temperature, key instrument telemetry such as the BB lifetime trends, the instrument temperature trends, the Cold Focal Plane telemetry and finally, the total assessed calibration uncertainty of the TEBs.

The Ocean Colour Monitor (OCM) sensor on-board the Oceansat-2 spacecraft has been operational since its launch in September, 2009. The Oceansat 2 OCM primary design goal is to provide continuity to Oceansat-1 OCM to obtain information regarding various ocean-colour variables. OCM acquires Earth scene measurements in eight multi-spectral bands in the range from 402 to 885 nm. The MODIS sensor on the Terra and Aqua spacecraft has been successfully operating for over a decade collecting measurements of the earth’s land, ocean surface and atmosphere. The MODIS spectral bands, designed for land and ocean applications, cover the spectral range from 412 to 869 nm. This study focuses on comparing the radiometric calibration stability of OCM using near-simultaneous TOA measurements with Terra and Aqua MODIS acquired over the Libya 4 target. Same-day scene-pairs from all three sensors (OCM, Terra and Aqua MODIS) between August, 2014 and September, 2015 were chosen for this analysis. On a given day, the OCM overpass is approximately an hour after the Terra overpass and an hour before the Aqua overpass. Due to the orbital differences between Terra and Aqua, MODIS images the Libya 4 site at different scan-angles on a given day. Some of the high-gain ocean bands for MODIS tend to saturate while viewing the bright Libya 4 target, but bands 8-10 (412 nm – 486 nm) provide an unsaturated response and are used for comparison with the spectrally similar OCM bands. All the standard corrections such as bidirectional reflectance factor (BRDF), relative spectral response mismatch, and impact for atmospheric water-vapor are applied to obtain the reflectance differences between OCM and the two MODIS instruments. Furthermore, OCM is used as a transfer radiometer to obtain the calibration differences between Terra and Aqua MODIS reflective solar bands.

Ocean Color Monitor-2 (OCM-2) on-board Oceansat 2 satellite is a multi-spectral sensor with a spatial resolution of 360×250m. Despite the presence of improved spatial resolution for better ocean color interpretation within coastal zones; differences among the OCM-2 detectors lead to striping artifacts in the along-track direction limiting the ocean color observations. Existing calibration methods do not characterize the striping noise efficiently. Destriping algorithms are generally applied to Level 2 radiance or biogeochemical products (i.e., post-radiometric and atmospheric correction), to remove the striping artifacts in order to ensure quality products. The present study focuses to reveal a robust method which effectively removes the striping effects in the TOA radiance products. Preliminary results obtained from this approach have been highlighted which show significant improvement in image quality for Level 1B (TOA radiance) and Level 2 (Water leaving radiance (L_w) and biogeochemical) products. The proposed method operates on a pixel by pixel basis with an aim to maintain the spatial and spectral resolution of data and ensure image quality in the derived products.

Atmospheric Motion Vector (AMV) over Indian Ocean and surrounding region is one of the most important sources of tropospheric wind information assimilated in numerical weather prediction (NWP) system. Earlier studies showed that the quality of Indian geo-stationary satellite Kalpana-1 AMVs was not comparable to that of other geostationary satellites over this region and hence not used in NWP system. Indian satellite INSAT-3D was successfully launched on July 26, 2013 with upgraded imaging system as compared to that of previous Indian satellite Kalpana-1. INSAT-3D has middle infrared band (3.80 - 4.00 μm) which is capable of night time pictures of low clouds and fog. Three consecutive images of 30-minutes interval are used to derive the AMVs. New height assignment scheme (using NWP first guess and replacing old empirical GA method) along with modified quality control scheme were implemented for deriving INSAT-3D AMVs. In this paper an attempt has been made to validate these AMVs against in-situ observations as well as against NCMRWF's NWP first guess for monsoon 2015. AMVs are subdivided into three different pressure levels in the vertical viz. low (1000 – 700 hPa), middle (700 – 400 hPa) and high (400 – 100 hPa) for validation purpose. Several statistics viz. normalized root mean square vector difference; biases etc. have been computed over different latitudinal belt. Result shows that the general mean monsoon circulations along with all the transient monsoon systems are well captured by INSAT-3D AMVs, as well as the error statistics viz., RMSE etc of INSAT-3D AMVs is now comparable to other geostationary satellites.

Space Applications Centre develops various electro-optical (EO) sensors for space borne platforms and inter-planetary missions. Sensor complexities vary for different applications and therefore performance evaluation and characterization pose different challenges. Performance optimization tasks demand repeated measurements and characterization needs to be done under different phases of testing. It is difficult to meet such requirements in case of short sensor development lifecycles or tight schedules. Activities which are amenable to automation are identified and targeted to reduce the manual intervention and to avoid delays due to errors and to speed up the overall activity.

Laboratory instruments, either in-house developed or COTS, play an important role in automating the test setup as they have different types of interfaces and have their own complications. In order to make an automated test setup, software intelligence need to be built based on the instrument feedback and the other check points based on the test sequence. A complete automation needs machine intelligence and sufficient amount of traceability, so that the process can be easily verified for confidence. Overall software architecture should be such that it allows connecting various types of instruments, decision making based on output of the device under test, complete traceability and fault tolerance.

In this paper authors have identified the activities that can be automated for various EO sensor categories and approaches are discussed for automation with radiometric calibration, spectral response measurement and focusing as test cases. Also, software architecture is presented which allows uniform access to instruments, back-end database and macro level automation process.

Drive electronics for generating fast, bipolar clocks, which can drive capacitive loads of the order of 5-10nF are indispensable for present day Charge Coupled Devices (CCDs). Design of these high speed bipolar clocks is challenging because of the capacitive loads that have to be driven and a strict constraint on the rise and fall times. Designing drive electronics circuits for space applications becomes even more challenging due to limited number of available discrete devices, which can survive in the harsh radiation prone space environment. This paper presents the design, simulations and test results of a set of such high speed, bipolar clock drivers. The design has been tested under a thermal cycle of -15 deg C to +55 deg C under vacuum conditions and has been designed using radiation hardened components. The test results show that the design meets the stringent rise/fall time requirements of 50±10ns for Multiple Vertical CCD (VCCD) clocks and 20±5ns for Horizontal CCD (HCCD) clocks with sufficient design margins across full temperature range, with a pixel readout rate of 6.6MHz. The full design has been realized in flexi-rigid PCB with package volume of 140x160x50 mm³.

Resourcesat-2A is a follow-on mission of Resourcesat-2, belongs to Indian Remote Sensing Program. It is expected to be launched in 2016 and is dedicated mainly to agricultural applications. One of the payloads, LISS3* is a medium resolution (23.5 m) sensor having four multispectral bands from 450 to 1650 nm. These spectral bands are named as B2 (550 nm), B3 (650 nm), B4 (815 nm) and B5 (1625 nm) respectively covering Visible, Near Infrared (NIR) and Short Wave Infrared (SWIR) regions. In order to provide quality data to the user community for long term scientific applications pre-flight ground calibration is carried out. This paper describes pre-flight spectral and radiometric calibration of LISS3* payload and its performance evaluation. Since it is a continuity mission to Resourcesat-2, which was launched in April 2011 so for generating long-term data record and correlation with previous observations, its parameters are compared with Resourcesat-2 LISS3* payload. The main spectral parameters like central wavelength, and pass band is determined using system level spectral response and compared for both the mission and differences are outlined. The next important exercise is pre-flight radiometric calibration, which was carried out in laboratory using a standard integrating sphere traceable to NIST standards. This paper highlights the technique adopted during pre-flight calibration of the radiometric response and performance assessment of all 4 bands of LISS3* in terms of major electro-optical parameters like Signal to Noise Ratio (SNR), Saturation Radiance (SR) etc. The observed SR shows that the sensor can measure spectral radiance from Earth up to 100% albedo.

The S-NPP VIIRS instrument has successfully operated since its launch in October 2011. The VIIRS Day-Night Band (DNB) is a panchromatic channel covering wavelengths from 0.5 to 0.9 μm that is capable of observing Earth scenes during both day and nighttime orbits at a spatial resolution of 750 m. To cover the large dynamic range, the DNB operates at low, mid, or high gain stages, and it uses an onboard solar diffuser (SD) for its low gain stage calibration. The SD observations also provide a means to compute gain ratios of low-to-mid and mid-to-high gain stages. This paper describes the DNB on-orbit calibration methodologies used by the VIIRS Characterization Support Team (VCST) in supporting the NASA earth science community with consistent VIIRS sensor data records (SDRs) made available by the Land Science Investigator-led Processing Systems (SIPS). It provides an assessment and update of DNB on-orbit performance, including the SD degradation in the DNB spectral range, detector gain and gain ratio trending, stray light contamination and its correction. Also presented in this paper are performance validations based on earth scenes and lunar observations.

A new approach to reconstruction of pseudo quad-polarized data from hybrid polarimetric data has been presented in this research. The algorithm is based on certain assumptions which were validated upon testing the aptness of the results and their comparison with true optical images of the region under study. This involved direct construction of the 3X3 coherency matrix from the 2X1 scattering matrices obtained from the hybrid polarimetric data. The reasonableness of the assumptions were tested by decomposing the reconstructed pseudo quad-pol data using a coherent decomposition mechanism. The data set used in this project was Level-1 FRS-1 Hybrid Polarimetric data and FRS-2 Quad-pol data of RISAT-1. Reliable scattering retrieval from SAR data involves the calibration of the data. Polarimetric calibration was performed on real and imaginary channels of the single look complex SAR data. The newly developed algorithm was implemented on calibrated data. To extract complete information of different scattering elements of any location, second order derivative of scattering matrix is the most suitable and widely used matrix. Coherency matrix of pseudo quad-pol obtained from hybrid polarimetric data using reconstruction algorithm was decomposed using Yamaguchi four component decomposition for scattering information extraction. The obtained surface, double-bounce and volume scattering were compared with the scattering elements of hybrid-polarimetric decomposition, m-alpha and decomposition of quad-pol data of RISAT-1. The comparison revealed that the results obtained were satisfactory and thus the assumptions made during the reconstruction of pseudo quad-pol data were reasonable for specific purposes. Further comparisons of results using different decompositions technique at pixel level comparison can help better understand the aptness of the algorithm.

The Geostationary Operational Environmental Satellite R (GOES-R) series is the planned next generation of operational weather satellites for the United States National Oceanic and Atmospheric Administration (NOAA). The National Aeronautics and Space Administration (NASA) is procuring the GOES-R spacecraft and instruments with the first launch of the GOES-R series planned for October 2016. Included in the GOES-R Instrument suite is the Geostationary Lightning Mapper (GLM). GLM is a single-channel, near-infrared optical detector that can sense extremely brief (800 μs) transient changes in the atmosphere, indicating the presence of lightning. GLM will measure total lightning activity continuously over the Americas and adjacent ocean regions with near-uniform spatial resolution of approximately 10 km.

Due to its large CCD (1372x1300 pixels), high frame rate, sensitivity and onboard event filtering, GLM will require extensive post launch characterization and calibration. Daytime and nighttime images will be used to characterize both image quality criteria inherent to GLM as a space-based optic system (focus, stray light, crosstalk, solar glint) and programmable image processing criteria (dark offsets, gain, noise, linearity, dynamic range). In addition ground data filtering will be adjusted based on lightning-specific phenomenology (coherence) to isolate real from false transients with their own characteristics. These parameters will be updated, as needed, on orbit in an iterative process guided by pre-launch testing. This paper discusses the planned tests to be performed on GLM over the six-month Post Launch Test period to optimize and demonstrate GLM performance.

The GOES-R magnetometer subsystem accuracy requirement is 1.7 nanoteslas (nT). During quiet times (100 nT), accuracy is defined as absolute mean plus 3 sigma error per axis. During storms (300 nT), accuracy is defined as absolute mean plus 2 sigma error per axis. Error comes both from outside the magnetometers, e.g. spacecraft fields and misalignments, as well as inside, e.g. zero offset and scale factor errors. Because zero offset and scale factor drift over time, it will be necessary to perform annual calibration maneuvers. To predict performance before launch, we have used Monte Carlo simulations and covariance analysis. With the proposed calibration regimen, both suggest that the magnetometer subsystem will meet its accuracy requirements.

The new-generation Himawari-8 geostationary meteorological satellite of the Japan Meteorological Agency (JMA) started operation in July 2015 after the completion of in-orbit testing and checking of the overall system. Himawari-8 features the new Advanced Himawari Imager (AHI), which has 16 bands and double the spatial resolution of its MTSAT-series predecessor satellites [1]. Full-disk imagery is obtained every 10 minutes, and regional observation at 2.5-minute intervals is also conducted. These significant improvements are expected to bring unprecedented levels of performance in nowcasting services and short-range weather forecasting systems. To leverage the full potential of the advanced imager, high precision in navigation and radiometric calibration is essential. This is estimated in off-line processes such as pattern matching for navigation and the Global Space-based Inter-Calibration System (GSICS) for radiometric calibration.

On 9 March 2016, JMA updated its ground processing system, including the image navigation and registration (INR) module, for further quality improvement. This update covered improvement of the band-to-band co-registration process for infrared bands, improvement of the resampling process, and implementation of a coherent noise reduction process. Results from the off-line processes showed that the update had improved Himawari Standard Data (HSD), which is Himawari-8/AHI L1B-equivalent data.