Emmanuel Mazy

OMC: An Optical Monitoring Camera for INTEGRAL Instrument description and performance

The Optical Monitoring Camera (OMC) will observe the optical emission from the prime targets of the gamma- ray instruments onboard the ESA mission INTEGRAL, with the support of the JEM-X monitor in the X-ray domain. This capability will provide invaluable diagnostic information on the nature and the physics of the sources over a broad wavelength range. Its main scientific objectives are: (1) to monitor the optical emission from the sources observed by the gamma- and X-ray instruments, measuring the time and intensity structure of the optical emission for comparison with variability at high energies, and (2) to provide the brightness and position of the optical counterpart of any gamma- or X-ray transient taking place within its field of view. The OMC is based on a refractive optics with an aperture of 50 mm focused onto a large format CCD (1024 2048 pixels) working in frame transfer mode (1024 1024 pixels imaging area). With a field of view of 5 5 it will be able to monitor sources down to magnitude V = 18. Typical observations will perform a sequence of dierent integration times, allowing for photometric uncertainties below 0.1 mag for objects with V 16.

The Mid-Infrared Instrument for the James Webb Space Telescope, II: Design and Build

The Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) provides measurements over the wavelength range 5 to 28.5 μm. MIRI has, within a single ‘package’, four key scientific functions: photometric imaging, coronagraphy, single-source low-spectral resolving power (R ∼ 100) spectroscopy, and medium-resolving power (R ∼ 1500 to 3500) integral field spectroscopy. An associated cooler system maintains MIRI at its operating temperature of <6.7 K. This paper describes the driving principles behind the design of MIRI, the primary design parameters, and their realisation in terms of the ‘as-built’ instrument. It also describes the test programme that led to delivery of the tested and calibrated Flight Model to NASA in 2012, and the confirmation after delivery of the key interface requirements.

First light of SWAP on-board PROBA2

The SWAP telescope (Sun Watcher using Active Pixel System detector and Image Processing) is an instrument launched on 2nd November 2009 on-board the ESA PROBA2 technological mission. SWAP is a space weather sentinel from a low Earth orbit, providing images at 174 nm of the solar corona. The instrument concept has been adapted to the PROBA2 mini-satellite requirements (compactness, low power electronics and a-thermal opto-mechanical system). It also takes advantage of the platform pointing agility, on-board processor, Packetwire interface and autonomous operations. The key component of SWAP is a radiation resistant CMOS-APS detector combined with onboard compression and data prioritization. SWAP has been developed and qualified at the Centre Spatial de Liège (CSL) and calibrated at the PTBBessy facility. After launch, SWAP has provided its first images on 14th November 2009 and started its nominal, scientific phase in February 2010, after 3 months of platform and payload commissioning. This paper summarizes the latest SWAP developments and qualifications, and presents the first light results.

Design and tests for the heliospheric imager of the STEREO mission

The Heliospheric Imager (HI) is part of the SECCHI suite of instruments on-board the two STEREO spacecrafts to be launched in 2005. The two HI instruments will provide stereographic image pairs of solar coronal plasma and coronal mass ejections (CME) over a wide field of view (~90°), ranging from 13 to 330 R0. These observations compliment the 15 R0 field of view of the solar corona obtained by the other SECCHI instruments (2 coronagraphs and an EUV imager). The key challenge of the instrument design is the rejection of the solar disk light, with total straylight attenuation of the order of 10-13 to 10-15. A multi-vane diffractive baffle system has been theoretically optimized to achieve the lower requirement (10-13 for HI-1) and is combined with a secondary baffling system to reach the 10-15 rejection performance in the second camera system (HI-2). This paper presents the last updates of the SECCHI/HI design concept, with the expected performance. A verification program is currently in progress. The on-going stray-light verification tests are discussed. A set of tests has been conducted in air, and under vacuum. The results are presented and compared with the expected theoretical data.

Design of the Heliospheric Imager for the STEREO mission

The Heliospheric Imager (HI) is part of the SECCHI suite of instruments on-board the two STEREO spacecrafts to be launched in 2005. The two HI instruments will provide stereographic image pairs of solar coronal plasma and address the observational problem of very faint coronal mass ejections (CME) over a wide field of view (~90 degree(s)) ranging from 13 to 330 R0. The key element of the instrument design is to reject the solar disk light, with straylight attenuation of the order of 10-13 to 10-15 in the camera systems. This attenuation is accomplished by a specific design of straylight baffling system, and two separate observing cameras with complimentary FOVs cover the wide FOV. A multi-vane diffractive system has been theoretically optimized to achieve the lower requirement (10-13 for HI-1) and is combined with a secondary baffling system to reach the 10-15 rejection performance in the second camera system (HI-2). This paper presents the design concept of the HI optics and baffles, and the preparation of verification tests that will demonstrate the instrument straylight performances. The baffle design has been optimized according to accommodation constrains on the spacecraft, and the optics were studied to provide adequate light gathering power and image quality. Straylight has been studied in the complete configuration, including the lens barrels and the focal plane assemblies. A specific testing facility is currently being studied to characterize the effective straylight rejection of the HI baffling. An overview of the developments for those tests is presented.

SWAP and LYRA: space weather from a small spacecraft

Two scientific instruments for Sun observations are being developed to be part of the payload of the ESAs second microsatellite, Proba-II (Project for On-board Autonomy). PROBA-2 is scheduled for launch in early 2007, on a low Earth orbit. Like Proba-1, in orbit since October 2001, Proba-2 is a 100-kilogram class spacecraft. PROBA-II will demonstrate new advanced technologies on its scientific payload but also on new platform subsystems such as star tracker, digital Sun sensor, cool gas generator, solar array concentrator, Li-Ion Battery, new central processor. This paper is dedicated to the solar payload, comprising the Sun Watcher using Active Pixel System detector and image Processing (SWAP) and the Lyman alpha Radiometer (LYRA), both aiming at Sun observations. SWAP, the Belgian-led main instrument, will continuously provide detailed images of the solar atmosphere, by the light of extreme ultraviolet rays, at 17.4 nm, completely absorbed by the terrestrial atmosphere. SWAP will perform as an operational solar monitoring tool for space weather forecasting while it will also demonstrate new technological solutions: CMOS/APS detector, new off-axis telescope design, a thermal structure. LYRA (LYman-alpha RAdiometer) is a small compact solar VUV radiometer. This instrument is designed, manufactured and calibrated by a Belgian-Swiss-German consortium. It will monitor the solar flux in four UV passbands. The spectral channels have been carefully selected for their relevance to space weather, solar physics and aeronomy, ranging from 1 nm to 220 nm. On the technological side, LYRA will benefit from the pioneering UV detectors program using diamond technology. The LYRA data will produce valuable solar monitoring information, for operational space weather nowcasting and research. This paper will detail the instrument concepts and their preparation for delivery to the platform.

NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 2-design, manufacturing, and testing of the ultraviolet and visible channel

NOMAD is a spectrometer suite on board the ESA/Roscosmos ExoMars Trace Gas Orbiter, which launched in March 2016. NOMAD consists of two infrared channels and one ultraviolet and visible channel, allowing the instrument to perform observations quasi-constantly, by taking nadir measurements at the day- and night-side, and during solar occultations. Here, in part 2 of a linked study, we describe the design, manufacturing, and testing of the ultraviolet and visible spectrometer channel called UVIS. We focus upon the optical design and working principle where two telescopes are coupled to a single grating spectrometer using a selector mechanism.

INTEGRAL's Optical Monitoring Camera stray-light design

The Optical Monitor Camera (OMC) is a part of the scientific payload of the INTEGRAL spacecraft, scheduled to be launched in 2001. The OMC is an imager that will monitor star variations in the V-band in a 5 X 5 degree field of view. It is required that the instrument detects object of plus 19.7 magnitude within the FOV. This requires highly sophisticated baffling techniques to provide attenuation up to 10-45. To obtain such performances, the design of each sub-element is optimized to fulfill very stringent stray-light requirements. The stray-light sources are discussed and performances are simulated with a 3D ray-tracing model.

Dynamic holography for the space qualification of large reflectors

The next generation of infrared - sub mm space telescopes requires reflectors with large dimensions, high quality and, according to weight issues, are based on composite or new materials technology. The challenging tasks of on-ground testing are to achieve the required accuracy in the measurement of these reflectors shape and antenna structures and to verify their performance under simulated space conditions (vacuum, low-high temperatures). A holographic camera for the verification and validation of this type of reflector in a space environment is presented. A diffuser is implemented to measure the deformations of reflective surfaces in a more flexible way. The system has been made compatible with the vacuum conditions. Some elements of the holographic camera (camera lenses, CCD, crystal, optical fibre) have been adapted and tested under vacuum. The metrological certification of the whole system is realised by the measurement of a parabolic CFRP reflector with a 1.1 meter diameter. The results are compared to the one achieved with a high spatial resolution IR interferometer on the same reflector in laboratory conditions and under thermal vacuum conditions. This later test consists in measuring the deformations of the reflector between an initial state at a selected temperature and a final state at another temperature. The comparison between the high spatial resolution IR interferometer and this dynamic holographic method showed very good qualitative and quantitative agreement between the techniques, thus verifying the potential of this new Holographic approach.

Design and performances of the heliospheric imager for the STEREO mission

The Heliospheric Imager (HI) is part of the SECCHI suite of instruments on-board the two STEREO spacecrafts to be launched in 2006. Located on two different orbits, the two HI instruments will provide stereographic images of solar coronal plasma and coronal mass ejections (CME) over a wide field of view (~90°), ranging from 13 to 330 solar radii (R0). These observations complete the 15 R0 field of view of the solar corona obtained with the other SECCHI instruments (2 coronagraphs and an EUV imager). The HI instrument is a combination of 2 refractive optical systems with 2 different multi-vanes baffle system. The key challenge of the instrument design is the rejection of the solar disk light, with total straylight attenuation of the order of 10-13 to 10-15. The optics and baffles have been specifically designed to reach the required rejection. This paper presents the SECCHI/HI opto-mechanical design, with the achieved performances. A test program has been run on one flight unit, including vacuum straylight verification test, thermo-optical performance test and co-alignment test. The results are presented and compared with the initial specifications.