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HyperScout-1 is based on a long line of development led by cosine measurement systems. The project to develop, build and launch the first HyperScout-1 was funded by ESA, with support from the Dutch, Belgian and Norwegian national space organizations: Netherlands Space Office, BELSPO and Norsk Romsenter. cosine, as the prime contractor, enlisted the help of consortium partners S&T, TU Delft, VDL and VITO.
The aim of the demonstration mission is to assess the quality of the data that will be acquired and the consequent suitability for the intended applications. Furthermore, the basic functionalities of the instrument as well as the onboard processing in real time will be demonstrated. The demonstration is divided in three operational blocks, during which HyperScout® will be operated to acquire data from invariant sites for vicarious calibration, from application sites to qualify HyperScout® for all the applications it has been conceived for, and to perform software experiments to demonstrate the novel approach to overcome the bandwidth limitation on small platforms.
The recent progress of manufacturing techniques favours this rapid change. For instance, for some applications the possibility to use a spectrometer with a magnification different from one is a key factor to enable instrument designs that are compact, cost effective and with high performance. This can be for instance achieved by using freeform or aspheric mirrors and freeform or spherical gratings. Other compact designs use instead linearly variable filters as dispersive devices, pointing to a different set of applications and performance.
The progress on small satellites and payloads, especially in the vision of large constellations, also benefits from the rapid development of imaging processing and deep learning machines, for instance equipping the payloads with powerful onboard data processor for real time generation of Level 2 data to face the challenge of handling the huge amount of data that is produced on-board.
By combining all these developments, it is possible to produce a portfolio of innovative multi/hyperspectral payloads covering a broad range of applications, spanning from high spatial resolution to large swath width, from minisatellite to cubesat format. Exploiting the flexibility and interoperability of these payloads, the users will be provided with turnkey solutions and real time response to their specific needs.
The European Space Agency is leading several R&D activities in the field of compact multispectral and hyperspectral payloads, fit for small platforms. These activities encompass technology development of novel optical designs, materials and processes, including also engineering of detectors, EEE components and dedicated data processing to achieve innovative and cost-effective solutions.
The paper provides an overview of the technology developments, the status of the instruments manufactured so far and those in operation, their performance and their expected applications. An example of an imaging spectrometer design that is extremely compact, realized with only two spherical optical elements and with a magnification different from one (1:3) is also addressed.
UHECRs can be studied in two ways: either via direct detection of the secondary particles, i.e. extensive air shower (EAS), produced by UEHRCs interaction with the atmosphere, or by observing during night the track of the UV fluorescence emitted by EAS. The origin direction of the cosmic rays can be therefore determined.
While ground-based observatories are already operative, different optical configurations, based mainly on the Schmidt camera layout or double Fresnel lenses concept, can be envisaged for future space-based ones. Both solutions faced in the past technological issues: transmission and resolution at large field angles for Fresnel lenses and weight of the primary mirror for the Schmidt. However, recent advances in the technology of ultra-lightweight, large and deployable active mirrors made the Schmidt camera approach feasible, becoming the preferred option.
This work describes a lightweight Schmidt space telescope design for UHECRs detection conceived for a mission intended to orbit at 600 km altitude.
The instrument concept is a fast, high-pixelized, large aperture and large Field-of-View (FoV) digital camera, working in the near-UV wavelength range with single photon counting capability. The telescope will record the track of an EAS with a time resolution of 2.5 μs and a spatial resolution of about 0.6 km (corresponding to ~ 4’), thus allowing the determination of energy and direction of the primary particles.
The proposed design has about 50° FoV and a 4.2 m entrance pupil diameter. The mirror is 7.5 m in diameter, it is deployable and segmented to fit the diameter of the considered launcher fairing (i.e. Ariane 6.2). The Schmidt corrector plate is a lightweight annular corona.
This configuration provides a polychromatic angular resolution less than 4' RMS over the whole FoV with a very fast relative aperture, i.e. F/# 0.7. Thanks to its very large pupil and large FoV, the design could be fit for a space-based observatory, thus enhancing the science achievable with respect to the presently operating ground-based counterparts, such as Telescope Array and Auger. A key advantage of this catadioptric design over the classic all refractive adopted in the past is the higher attainable global throughput. This parameter guarantees to reach and fulfil the required instrument photon collection specifications.
The innovation of this proposed star tracker is conceived by using spatial filtering with a concept complementary to that of coronagraph for sun corona observation, allowing to drastically reduce the size of the shadow. It can also work close to antennas and other part of the platform, which, when illuminated by the sun, become secondary sources capable to blind the star tracker.
This kind of accommodation offers three main advantages: no cumbersome shadows (baffle), maximum flexibility in terms of mission profile, less platform location constraints.
This new star sensor concept, dated 2007, is now patent pending. Galileo Avionica (now Selex Galileo) is the owner of the patent.
The presented advanced detection system is a spaceborne LEO telescope, with better performance than ground-based observatories, detecting up to 103 - 104 events/year. Different design approaches are implemented, all with very large FOV and focal surface detectors with sufficient segmentation and time resolution to allow precise reconstructions of the arrival direction. In particular, two Schmidt cameras are suggested as an appropriate solution to match most of the optical and technical requirements: large FOV, low f/#, reduction of stray light, optionally flat focal surface, already proven low-cost construction technologies. Finally, a preliminary proposal of a wideFOV retrofocus catadioptric telescope is explained.
The high versatility of these concepts allows to exploit the presented technology for any project willing to consider large aperture, segmented lightweight telescopes. A possible scientific application is for Ultra High Energy Cosmic Rays detection through the fluorescence traces in atmosphere and diffused Cerenkov signals observation via a Schmidt-like spaceborne LEO telescope with large aperture, wide Field of View (FOV) and low f/#.
A technology demonstrator has been manufactured and tested in order to investigate two project critical areas identified during the preliminary design: the performances of the long-stroke actuators used to implement the mirror active control and the mirror survivability to launch. In particular, this breadboard demonstrates at first that the mirror actuators are able to control with the adequate accuracy the surface shape and to recover a deployment error with their long stroke; secondly, the mirror survivability has been demonstrated using an electrostatic locking between mirror and backplane able to withstand without failure a vibration test representative of the launch environment.
The study is mainly addressed to a DIAL (Differential Absorption Lidar) at 935.5 nm for the measurement of water vapour profile in atmosphere, to be part of a typical small ESA Earth Observation satellite to be launched with ROCKOT vehicle. A detailed telescope optical design will be presented, including the results of angular and spatial resolution, effective optical aperture and radiometric transmission, optical alignment tolerances, stray-light and baffling. Also the results of a complete thermo-mechanical model will be shown, discussing temporal and thermal stability, deployment technology and performances, overall mass budget, technological and operational risk and system complexity.
Aim of this paper is to present the latest developments on the main issues related to the fabrication of a breadboard, covering two project critical areas identified during the preliminary studies: the design and performances of the long-stroke actuators used to implement the mirror active control and the mirror survivability to launch via Electrostatic Locking (EL) between mirror and backplane. The described work is developed under the ESA/ESTEC contract No. 22321/09/NL/RA.
The lightweight mirror is structured as a central sector surrounded by petals, all of them actively controlled to reach the specified shape after initial deployment and then maintained within specs for the entire mission duration. The presented study concerns: a) testing the Carbon Fiber Reinforced Plastic (CFRP) backplane manufacturing and EL techniques, with production of suitable specimens; b) actuator design optimisation; c) design of the deployment mechanism including a high precision latch; d) the fabrication of thin mirrors mock-ups to validate the fabrication procedure for the large shells.
The current activity aims to the construction of an optical breadboard capable of demonstrating the achievement of all these coupled critical aspects: optical quality of the thin shell mirror surface, actuators performances and back-plane - EL subsystem functionality.
The Vegetation Instrument is a high spatial resolution pushbroom 4 spectral bands imager composed of three distinct Spectral Imagers (SI). Each SI has 34° Field Of View (FOV) across track, and the total FOV of the VI is 102°, covering an Earth swath of 2260 Km with ground sampling distance down to 96 m at Nadir for VNIR bands.
The spectral bands are centred around 460 nm for the blue, 655 nm for the red, 845nm for the NIR and 1600 nm for the SWIR. The imaging telescope is built from a Three-Mirrors Anastigmat (TMA) configuration, including two highly aspheric mirrors. The optics is manufactured from special grade aluminium by diamond turning. The material being identical to the whole structure, no defocus or stresses build up with temperature variations in flight.
This paper gives an overview of the VI performances, and focuses on the results of the optical tests and on-ground calibrations.
1) control accuracy in the mirror surface shaping. 2) mirror survivability to launch.
The aim is to evaluate the effective performances of the long stroke smart-actuators used for the mirror control and to demonstrate the effectiveness and the reliability of the electrostatic locking (EL) system to restraint the thin shell on the mirror backup structure during launch. The paper presents a comprehensive vision of the breadboard focusing on how the requirements have driven the design of the whole system and of the various subsystems. The manufacturing process of the thin shell is also presented.
This paper presents a conceptual design of a facility placed in a vacuum chamber to eliminate undesired air particles scatter light sources. The specification of the clean room class or vacuum will depend on the required rejection to be measured. Once the vacuum chamber is closed, the stray light level from the external environment can be considered as negligible. Inside the chamber a dedicated baffle design is required to eliminate undesired light generated by the set up itself e.g. retro reflected light away from the instrument under test. This implies blackened shrouds all around the specimen. The proposed illumination system is a 400 mm off axis parabolic mirror with a focal length of 2 m. The off axis design suppresses the problem of stray light that can be generated by the internal obstruction. A dedicated block source is evaluated in order to avoid any stray light coming from the structure around the source pinhole. Dedicated attention is required on the selection of the source to achieve the required large measurement dynamic.
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