KEYWORDS: Systems modeling, Equipment, Design, Astronomy, Spectrographs, Systems engineering, Model based design, Interfaces, Instrument modeling, Modeling
ANDES (ArmazoNes high Dispersion Echelle Spectrograph) is one of the second-phase instruments planned for the Extremely Large Telescope (ELT) of ESO. ANDES will provide high-resolution spectroscopy in the visible and near-infrared wavelengths, enabling a wide range of scientific investigations, such as characterizing exoplanet atmospheres, testing fundamental physics, and measuring the cosmic expansion. In this paper, we present the general strategy of the Model-Based Systems Engineering (MBSE) approach that we have used to design the instrument during the Phase B-One, which covers the system architecture review (SAR) successfully completed at end 2023. We describe how we have applied the Cameo Systems Modeler tool to create and manage the system model in compliance with the SysML standard to perform requirements and interfaces management, structure verification and validation, and trade-off analysis. We also emphasize that ANDES is used as a test case for the application of the MBSE methodology in the astronomical field, in order to create a standard of procedures to perform all the actions and tasks that serve to satisfy all the steps in the various design phases of an ESO project. In fact, the initial phases require specific tasks, such as the analysis of requirements, the flow-down of specifications to the subsystems, the tracing of interfaces, the analysis of budgets. Since there is no tool that specifically encompasses all these capabilities in the astronomical field, it is necessary to define a robust methodology that can be taken as an example for future astronomical instrumentation. We discuss the benefits and challenges of using MBSE for ANDES, as well as the lessons learned and best practices that can be useful for other astronomical instrument projects.
Recently, the Italian astronomical community has begun adopting Model Based System Engineering (MBSE) for the development of complex instruments. A significant challenge is the establishment of a robust and flexible method to manage all system aspects, among which the interfaces. This paper presents an in-progress method to trace and verify the interfaces of ANDES, the high-resolution spectrograph for the ELT telescope. The method is part of a customization of SysML language capabilities in Cameo Systems Modeler to meet the needs of the astronomical field. The method uses the nature of the interfaces to populate the interface blocks used to represent the interfaces in the system and to store the numerical and literal values that define the interfaces. The verification process checks if the client side complies with the constraints the host imposes. This whole process employs the use of computational blocks prepared in advance and reused for each interface to lighten the set-up effort and reduce human errors. The application of this methodology shall largely improve interface management leading to more efficient and safer evaluations compared to traditional methods.
Morfeo (Multi-conjugate adaptive Optics Relay For ELT Observations) is an adaptive optics module able to compensate the wavefront disturbances affective the scientific observation. It will be installed on the straight-through port of the telescope Nasmyth platform to serve the first-light instrument MICADO and with the provision for a future second instrument. The module underwent the Preliminary Design Review in 2021 and is expected to be commissioned in 2029. In this paper we present a synthesis of the System Engineering approach adopted to manage the development of the instrument assessing the criticalities of phase B (preliminary design) and preliminary phase C (final design). We will discuss the evolution of the system engineering approach, identifying within the MBSE framework the evolution of the various modelling artefacts. towards the requirements. We will detail the criticalities of the system engineering with a particular focus onto the management of the interfaces between subsystems and external systems (Telescope, other instruments…).
In this paper we will make a revision of the usage of MBSE for an astronomy-oriented instrument. We will in particular trade the benefit Versus the overhead with respect of the traditional System engineering method. We will compare different ground-based instruments for different telescope size in different project phases. We will try then to underline where MBSE have been useful and where the criticalities of this method emerged in order to draw a possible roadmap to exploit the maximum benefit achievable by this method. In detail we will focus on four main aspects. In the first part We will compare different requirement management approaches. Second, we will focus on the Interface management which is one of the most critical elements of the system engineering discipline. We will then compare the product traditional product modelling (excel based) with respect to a database oriented one. Finally, we will assess the use cases management. We will compare traditional Versus MBSE in order to allow the reader to identify which of the two approaches better fits with its needs.
Lately, the Italian astronomical community has begun the transition to Model Based System Engineering (MBSE). This tool has been largely applied to the development of the Cassegrain U-Band Efficient Spectrograph (CUBES) designed to provide high instrumental efficiency ( > 37 %) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R > 20, 000 (with a lower-resolution, skylimited mode of R ≈ 7, 000). Here, MBSE has been used mainly in 3 areas: requirements management, activities modeling, and generation of system structure documents, like the Product Breakdown Structure (PBS) or the Bill of Materials (BoM). Requirements management controls the flow-down process to have a coherent list of requirements. This is achieved using derived properties and tailored numbering. Activities modeling uses traditional MBSE techniques while mimicking the software templates for calibration and observation. To generate structural documents, the system structure is generated in Cameo using the outputs from the subsystems, granting high coherency between the model and the actual design state. The interaction with non-Cameo users relies on Excel files, accessible to all interested parties and usable by Cameo to export and import information.
The Italian astronomical community has begun adopting Model Based System Engineering (MBSE) to develop complex instruments using Cameo Systems Modeler targeting various system engineering tasks including requirements management, system structure management, activities modelling and simulation, and many more. Lately, the focus moved also to managing the system interfaces and the associated cabling and connectors. The proposed methodology uses interface blocks to represent the connectors and their location in the system. The interface blocks generate a proxy port owned by the structural element they are applied to. These ports are then connected to represent the interactions among parts, subsystems, and with external actors using SysML connectors. The connectors are then refined through association blocks also used to represent the cable with all their characteristics. The association blocks are linked to the structural blocks as their parts leading to their inclusion in the PBS of the subsystems. The main output is a table listing all the cables of the system, their connectors, the system parts they connect, and other specifics of the cable like its length, weight, and so on.
We present here the preliminary design of the RIZ module, one of the visible spectrographs of the ANDES instrument. It is a fiber-fed high-resolution, high-stability spectrograph. Its design follows the guidelines of successful predecessors such as HARPS and ESPRESSO. In this paper we present the status of the spectrograph at the preliminary design stage. The spectrograph will be a warm, vacuum-operated, thermally controlled and fiber-fed echelle spectrograph. Following the phase A design, the huge etendue of the telescope will be reformed in the instrument with a long slit made of smaller fibers. We discuss the system design of the spectrographs system.
The first generation of ELT instruments includes an optical-infrared High Resolution Spectrograph, ANDES (ArmazoNes high Dispersion Echelle Spectrograph). The optical design and architecture of ANDES is primarily dictated by its high spectral resolving power (R=100'000), the area of the spectrograph slit projected onto the sky (> 1 arcsec2), its broad wavelength coverage and the large primary mirror of the ELT, and must foresee several huge fiber-fed spectrograph units. One of them is the RIZ spectrograph, covering wavelengths from 620 to 960 nm. It deals with a recomposed ~40-mm-long entrance slit and a pupil anamorphic magnification to overcome the limitation size of a mosaic 1.6-meter R4 Echelle grating. It requires two fast cameras with F/# close to the unity. This paper describes the preliminary optical design of the RIZ spectrograph instrument, its challenges, and its nominal and expected performances.
We present the design of the ANDES UBV module, the bluest spectrograph of the ANDES instrument. It is a fiber-fed high resolution, high stability spectrograph, which will be installed on the ELT-Nasmyth platform to minimize blue fibre losses from the focal plane to the spectrograph. In this paper we present the status of development of the spectrograph, its optical design, and auxiliary devices like exposure meter and leveling system, at the preliminary design stage. As stability is the prime design driver, a thermal enclosure is provided to keep temperature of the optical train stable at ambient conditions, and the pressure is kept constant at high vacuum level. The science, sky background and simultaneous calibration light is fed to the spectrographs via fiber bundles of 66 fibres, which are arranged in a straight row forming the spectrograph slit.
In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high instrumental efficiency ( > 37%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R > 20, 000 (with a lower-resolution, sky-limited mode of R ∼ 7, 000). With the design focusing on maximizing the instrument throughput (ensuring a Signal to Noise Ratio – SNR– ∼ 20 per spectral resolution element at 313 nm for U ∼ 17.5 mag objects in 1h of observations), it will offer new possibilities in many fields of astrophysics: i) access to key lines of stellar spectra (e.g. lighter elements, in particular Beryllium), extragalactic studies (e.g. circumgalactic medium of distant galaxies, cosmic UV background) and follow-up of explosive transients. We present the CUBES instrument design, currently in Phase-C and approaching the final design review, summarizing the hardware architecture and interfaces between the different subsystems as well as the relevant technical requirements. We describe the optical, mechanical, electrical design of the different subsystems (from the telescope adapter and support structure, through the main opto-mechanical path, including calibration unit, detector devices and cryostat control, main control electronics), detailing peculiar instrument functions like the Active Flexure Compensation (AFC). Furthermore, we outline the AIT/V concept and the main instrument operations giving an overview of its software ecosystem. Installation at the VLT is planned for 2028/2029 and first science operations in late 2029.
We describe the instrument’s design and architecture, emphasizing its unique features. The design is driven by requirements on resolving power, slit area, spectral coverage and stability. The instrument can operate in seeinglimited or SCAO modes, with options for sky and/or calibration measurements. In SCAO mode, it can use a small Integral Field Unit (IFU) with different spaxel scales. The light from the telescope reaches the Front-End on the Nasmyth platform, which has four insertable modules: two seeing-limited arms, one SCAO arm and one IFU arm. They are connected by fibres or fibre bundles to the Spectrographs in different locations: the Nasmyth Platform and the Coud´e room. The wavelength splitting depends on the fibre transparency. The subsystems are placed at different distances from the telescope. In Phase-B-one, we performed analyses to define the best trade-off for the budgets and architecture. We extended the spectrographs toward the goal ranges as much as possible. ANDES is complex, but its sophisticated and modular design will enable next-generation astronomy research.
The Extremely Large Telescopes (ELTs), thanks to their large apertures and cutting-edge Multi-Conjugate Adaptive Optics (MCAO) systems, promise to deliver sharper and deeper data even than the JWST. SHARP is a concept study for a near-IR (0.95-2.45 μm) spectrograph conceived to fully exploit the collecting area and the angular resolution of the upcoming generation of ELTs. In particular, SHARP is designed for the 2nd port of MORFEO@ELT. Composed of a Multi-Object Spectrograph, NEXUS, and a multi-Integral Field Unit, VESPER, MORFEO-SHARP will deliver high angular (∼30 mas) and spectral (R≃300, 2000, 6000, 17000) resolution, outperforming NIRSpec@JWST (100 mas). SHARP will enable studies of the nearby Universe and the early Universe in unprecedented detail. NEXUS is fed by a configurable slit system deploying up to 30 slits with ∼2.4” length and adjustable width, over a field of about 1.2’×1.2’ (35 mas/pix). Each slit is fed by an inversion prism able to rotate by an arbitrary angle the field that can be seen by the slit. VESPER is composed of 12 probes of 1.7”×1.5” each (spaxel 31 mas) probing a field 24”×70”. SHARP is conceived to exploit the ELT aperture reaching the faintest flux and the sharpest angular resolution by joining the sensitivity of NEXUS and the high spatial sampling of VESPER to MORFEO capabilities. This article provides an overview of the scientific design drivers, their solutions, and the resulting optical design of the instrument achieving the required optical performance.
KEYWORDS: Telescopes, James Webb Space Telescope, Design and modelling, Vibration, Space operations, Astronomical imaging, Actuators, Mirrors, Glasses, Disk lasers
The latest high-performance telescopes for deep space observation employ very large primary mirrors that are made of smaller segments, like the JWST which employs monolithic beryllium hexagonal segments. A very promising development stage of these systems is to make them active and to operate on their reflective surfaces to change their shape and compensate for aberrations as well as to perform a very precise alignment. This is possible by employing a reference body that stores actuators to modify the shape of the shell, like in the SPLATT project where voice coil actuators are used. However, the lack of physical contact between the main body and shell places – along with the many advantages related to the physical decoupling of the two bodies - some concerns related to the retaining of the shell under all the possible acceleration conditions affecting the system during the mission lifetime. This paper aims to study the acceleration environment affecting the spacecraft during its lifetime and to use it as a baseline for operational requirements of a retaining system for the shells. Any solution is selected in this paper to leave complete freedom for the development of a constraining system, just some are qualitatively discussed.
In the last few years the concept of an active space telescope has been greatly developed, to meet demanding requirements with a substantial reduction of tolerances, risks and costs. This is the frame of the LATT project (an ESA TRP) and its follow-up SPLATT (an INAF funded R&D project). Within the SPLATT activities, we outline a novel approach and investigate, both via simulations and in the optical laboratory, two main elements: an active segmented primary with contactless actuators and a pyramid wavefront sensor (PWFS) to drive the correction chain. The key point is the synergy between them: the sensitivity of the PWFS and the intrinsic stability of a contactless-actuated mirror segment. Voice-coil, contactless actuators are in facts a natural decoupling layer between the payload and the optical surface and can suppress the high frequency vibration as we verified in the lab. We subjected a 40 cm diameter prototype with 19 actuators to an externally injected vibration spectrum; we then measured optically the reduction of vibrations when the optical surface is floating controlled by the actuators, thus validating the concept at the first stage of the design. The PWFS, which is largely adopted on ground-based telescope, is a pupil-conjugated sensor and offers a user-selectable sampling and capture range, in order to match different use cases; it is also more sensitive than Shack-Hartmann sensor especially at the low-mid spatial scales. We run a set of numerical simulations with the PWFS measuring the misalignment and phase steps of a JWST-like primary mirrors: we investigated the PWFS sensitivity in the sub-nanometer regime in presence of photon and detector noise, and with guide star magnitudes in the range 8 to 14. In the paper we discuss the outcomes of the project and present a possible roadmap for further developments.
MORFEO (formerly known as MAORY) is a post-focal adaptive optics module that forms part of the first light instrument suite for the Extreme Large Telescope (ELT). The project passed the Preliminary Design Review in two stages in April and July 2021 and is now entering the Final Design Phase. In this paper we report the status of the project.
Large format deformable mirrors have been proposed in the last few years as key elements to implement active wave front correction for future space telescopes. Active optics is, in fact, an enabling technology for high stability, high contrast and high resolution systems. We present in this work a 40 cm diameter prototype, together with its laboratory characterization, based on voice-coil actuators. When the mirror is operated, such contact-less actuation allows the optical surface to float at a given distance from its support and the mirror is virtually decoupled from the mechanics; such condition offers an intrinsic isolation from external vibrations with no need for further damping devices. We demonstrated experimentally this concept in the laboratory on a dedicated interferometric setup, registering a substantial rejection of the vibrations injected. We will present in this work the test results and a roadmap for future developments.
System engineering and project-team management are essential tools to ensure the project success and the Redmine is a valuable platform for the work organization and for a system engineered approach. We review in this work the management needs related to our project, and suggest the possibility that they fit to many research activities with a similar scenario: small team, technical difficulties (or unknowns), intense activity sprints and long pauses due to external schedule management, a large degree of shared leadership. We will then present our implementation with the Redmine, showing that the use of the platform resulted in a strong engagement and commitment of the team. The explicit goal of this work is also to rise, at least internally, the awareness about team needs and available organizational tools and methods; and to highlight a shareable approach to team management and small scale system engineering.
MORFEO (formerly known as MORFEO) an adaptive optics module able to compensate the wavefront disturbances affective the scientific observation. It will be installed on the straight-through port of the telescope Nasmyth platform to serve the first-light instrument MICADO and with the provision for a future second instrument. The module underwent the Preliminary Design Review in 2021 and is expected to be commissioned in 2029. In this paper we present a synthesis of the System Engineering approach adopted to manage the development of the instrument. We will discuss the evolution of the architecture towards the requirements. We will detail the criticalities of the system engineering with a particular focus onto the management of the interfaces between subsystems and external systems (Telescope, other instruments…). We will also make a brief description of way in which we implemented Model Based System Engineering and the tools adopted in order to manage requirements, use cases and interfaces.
Systems Engineering requires the involvement of different engineering disciplines: Software, Electronics, Mechanics (often nowadays together as Mechatronics), Optics etc. Systems Engineering of Astronomical Instrumentation is no exception to this. A critical point is the handling of the different point of view introduced by these disciplines often related to different tools and cultures. Model Based Systems Engineering (MBSE) approach can help the Systems Engineer to always have a complete view of the full system. Moreover, in an ideal situation, all of the information resides in the model thus allowing different views of the System without having to resort to different sources of information, often outdated. In the real world, however, this does not happen because the different actors (Optical Designers, Mechanical Engineers, Astronomers etc.) should adopt the same language and this is clearly, at least nowadays and for the immediate future, close to impossible. In the Italian Astronomical Community, we are developing methodologies and tools to share the expertise in this field among the different projects. In this paper we present the status of this activity that aims to deliver to the community proper tools and template to enable a uniformed use of MBSE (friendly name Astro MBSE) among different projects (ground and space based). We will analyze here different software and different approaches. The target and synthesis of this work will be a support framework for the MBSE based system Engineering activity to the Italian Astronomical Community (INAF).
Systems Engineering requires the involvement of different engineering disciplines: Software, Electronics, Mechanics (often nowadays together as Mechatronics), Optics etc. Systems Engineering of Astronomical Instrumentation is no exception to this. A critical point is the handling of the requirements, their tracing, flow down and the interaction with stakeholders (flow up) and subsystems (flow down) in order to have traceable and methodical evolution and management. In the Italian Astronomical Community, we are developing methodologies and tools to share the expertise in this field among the different projects. In this paper we will focus on the requirement management approach among different projects (ground and space based). We will analyses here different architectures and tools in order to provide to the end user a useful tool optimized for Astronomical instrumentation. The target and synthesis of this work will be a support framework for the Requirement management of the Italian Astronomical Community (INAF) projects.
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