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See detailThe Hot and Energetic Universe: The X-ray Integral Field Unit (X-IFU) for Athena+
Barret, D.; den Herder, J. W.; Piro, L. et al

Report (2013)

The Athena+ mission concept is designed to implement the Hot and Energetic Universe science theme submitted to the European Space Agency in response to the call for White Papers for the definition of the ... [more ▼]

The Athena+ mission concept is designed to implement the Hot and Energetic Universe science theme submitted to the European Space Agency in response to the call for White Papers for the definition of the L2 and L3 missions of its science program. The Athena+ science payload consists of a large aperture high angular resolution X-ray optics and twelve meters away, two interchangeable focal plane instruments: the X-ray Integral Field Unit (X-IFU) and the Wide Field Imager (WFI). The X-IFU is a cryogenic X-ray spectrometer, based on a large array of Transition Edge Sensors (TES), offering 2.5 eV spectral resolution, with ~5" pixels, over a field of view of 5 arc minutes in diameter. In this paper, we briefly describe the Athena+ mission concept and the X-IFU performance requirements. We then present the X-IFU detector and readout electronics principles, the current design of the focal plane assembly, the cooling chain and review the global architecture design. Finally, we describe the current performance estimates, in terms of effective area, particle background rejection, count rate capability and velocity measurements. Finally, we emphasize on the latest technology developments concerning TES array fabrication, spectral resolution and readout performance achieved to show that significant progresses are being accomplished towards the demanding X-IFU requirements. [less ▲]

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See detailCHEOPS: A transit photometry mission for ESA's small mission programme
Broeg, C.; Fortier, A.; Ehrenreich, D. et al

in Saglia, Roberto (Ed.) European Physical Journal Web of Conferences (2013, April 01)

Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground based transit searches now reach milli-mag photometric precision and ... [more ▼]

Ground based radial velocity (RV) searches continue to discover exoplanets below Neptune mass down to Earth mass. Furthermore, ground based transit searches now reach milli-mag photometric precision and can discover Neptune size planets around bright stars. These searches will find exoplanets around bright stars anywhere on the sky, their discoveries representing prime science targets for further study due to the proximity and brightness of their host stars. A mission for transit follow-up measurements of these prime targets is currently lacking. The first ESA S-class mission CHEOPS (CHaracterizing ExoPlanet Satellite) will fill this gap. It will perform ultra-high precision photometric monitoring of selected bright target stars almost anywhere on the sky with sufficient precision to detect Earth sized transits. It will be able to detect transits of RV-planets by photometric monitoring if the geometric configuration results in a transit. For Hot Neptunes discovered from the ground, CHEOPS will be able to improve the transit light curve so that the radius can be determined precisely. Because of the host stars' brightness, high precision RV measurements will be possible for all targets. All planets observed in transit by CHEOPS will be validated and their masses will be known. This will provide valuable data for constraining the mass-radius relation of exoplanets, especially in the Neptune-mass regime. During the planned 3.5 year mission, about 500 targets will be observed. There will be 20% of open time available for the community to develop new science programmes. [less ▲]

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See detailThe x-ray microcalorimeter spectrometer onboard Athena
den Herder, J. W.; Bagnali, D.; Bandler, S. et al

in Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series (2012, September 01)

One of the instruments on the Advanced Telescope for High-Energy Astrophysics (Athena) which was one of the three missions under study as one of the L-class missions of ESA, is the X-ray Microcalorimeter ... [more ▼]

One of the instruments on the Advanced Telescope for High-Energy Astrophysics (Athena) which was one of the three missions under study as one of the L-class missions of ESA, is the X-ray Microcalorimeter Spectrometer (XMS). This instrument, which will provide high-spectral resolution images, is based on X-ray micro-calorimeters with Transition Edge Sensor (TES) and absorbers that consist of metal and semi-metal layers and a multiplexed SQUID readout. The array (32 x 32 pixels) provides an energy resolution of < 3 eV. Due to the large collection area of the Athena optics, the XMS instrument must be capable of processing high counting rates, while maintaining the spectral resolution and a low deadtime. In addition, an anti-coincidence detector is required to suppress the particle-induced background. Compared to the requirements for the same instrument on IXO, the performance requirements have been relaxed to fit into the much more restricted boundary conditions of Athena. In this paper we illustrate some of the science achievable with the instrument. We describe the results of design studies for the focal plane assembly and the cooling systems. Also, the system and its required spacecraft resources will be given. [less ▲]

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See detailJupiter system Ultraviolet Dynamics Explorer (JUDE), an instrument proposed for the ESA-JUICE mission
Grodent, Denis ULg; Bunce, Emma J.; Renotte, Etienne ULg et al

Report (2012)

In the proposal that follows we present a detailed concept for the science case, instrument requirements, technical design, calibration and operations, management structure, and financial plan for the ... [more ▼]

In the proposal that follows we present a detailed concept for the science case, instrument requirements, technical design, calibration and operations, management structure, and financial plan for the Jupiter system Ultraviolet Dynamics Experiment (JUDE), which will provide an outstanding solution to the UV instrumentation requirements for the JUICE mission. The JUDE instrument will represent a novel technical capability in UV instrumentation for planetary science, and will deliver the first true UV imaging capability beyond Earth orbit. The JUDE instrument design consists of two separate channels – the imaging channel (ImaC) and the spectrograph channel (SpeC), neither of which has any moving parts. This simple combination of two autonomous channels allows a true image and a spectrum at FUV wavelengths to be obtained simultaneously, allowing science goals to be realised which are not possible with a traditional scanning-slit imaging-spectrograph design The international consortium assembled to build the JUDE instrument is formed of two institutes from two European countries, and one from the United States. Prof. Denis Grodent (Université de Liège, Belgium) will act as the PI for the entire instrument team and the ULg/CSL team will provide a substantial hardware contribution to the instrument in the form of the optics, coatings, and Data Processing Unit (DPU). Dr Emma Bunce (University of Leicester, UK) will act as Co-PI for the instrument and the UoL team will supply the Micro-Channel Plate (MCP) detectors and read-out electronics. Prof. John Clarke (Co-I) of Boston University, USA will provide the grating element for the spectral channel of the instrument, in addition to instrument calibration activities. The science Co-Is are gathered from multiple institutes/nations including Belgium, UK, Germany, Italy, and the United States (see Part 1 for the full team list). Collectively, the team have decades of expertise in the areas of outer planet magnetospheres, planetary auroral and atmospheric emissions and surface UV observations from multiple platforms including Cassini UVIS, Juno UVS, Hubble Space Telescope, and numerous terrestrial missions. The team also have roles on non-UV instruments which will maximise the interpretation of the JUDE data. The two instrument channels are built on proven and robust technology with much flight heritage (e.g. Juno, Cassini, BepiColombo, IMAGE, ROSAT, Chandra, Voyager, Freja, DE-1, Swift). More specifically, the optics and focal plane detector proposed for the JUDE instrument are widely based on previous designs by CSL, at the ULg and UoL, for the FUV Spectro-Imager on the NASA IMAGE spacecraft, the UV Spectrograph on the NASA Juno mission to Jupiter, and the ROSAT Wide Field Camera. The data return from the instrument will greatly benefit the European and international science communities in planetary and terrestrial sciences, and the knowledge obtained will be generally applicable to broader astrophysics disciplines (e.g. extrasolar planetary physics). In answering the UV science objectives for the JUICE mission the JUDE instrument will clearly address the ESA Cosmic Vision Themes 1: What are the conditions for planet formation and the emergence of life? and 2: How does the Solar System work? The JUDE images (in particular) provide a clear path towards a high-level related programme of education and public outreach which the JUDE team are well equipped and keen to exploit. The JUDE instrument will contribute to all of the UV-related science objectives of JUICE, plus additional science objectives not listed in the Science Requirements Matrix. - At Ganymede and other moons (Europa and Callisto) JUDE will contribute directly to breakthroughs in the following scientific areas: 1) the characterisation of local environment, specifically through the first investigation of the morphology and variation of Ganymede’s aurora. A clear understanding of the auroral and atmospheric emissions at Ganymede will provide vital information on their formation mechanisms and will contribute to studies of the interaction of the Ganymede magnetosphere with Jupiter’s magnetosphere; 2) the first detailed observations of the satellites’ atmospheric (exosphere/ionosphere) composition and structure through measurements of their atmospheric emission and absorption spectra during multiple stellar occultation opportunities; and 3) the study of the satellites surface composition using surface reflectance measurements. The measurements at UV wavelengths are essential because they allow the study of the relationship between the satellites’ surface weathering, their atmospheres and the external environment which is mainly affected by the surrounding Jovian magnetosphere. By carefully studying processes at the surface and in the satellites’ atmospheres together, JUDE will provide the information required to distinguish between two classes of compositional heterogeneities at the satellites’ surfaces: 1) heterogeneities that arise from interaction with the external environment; 2) heterogeneities that arise from dynamical interaction with the subsurface. - With respect to Jupiter, JUDE will: 1) provide “state of the art” measurements of the Jovian atmospheric dynamics and transport through high temporal and spatial resolution auroral imaging; 2) allow a new understanding of the Jovian magnetosphere as a fast rotator through interpretation of the Jovian aurora as direct evidence for the 3D magnetosphere dynamics – a view which is continuously available in the planet’s upper atmosphere (independent of the spacecraft location within the magnetosphere); 3) investigate the magnetosphere as a giant accelerator through observations of the field-aligned current systems responsible for acceleration of electrons (and production of aurora); 4) discover the plasma sources and sinks of the moons through auroral imaging of the moon footprints in Jupiter’s atmosphere as a witness of the electromagnetic interactions taking place; 5) obtain new information on Jupiter’s atmospheric structure and composition through multiple stellar occultation opportunities. In addition, JUDE will make remote observations of the Io torus emissions and will provide the first in situ observation of the variability of the torus, over the lifetime of the mission, providing important information about the internal activity of the moon. JUDE offers a unique opportunity to obtain the first concurrent datasets of the different coupled elements of the Jupiter system: Io's atmosphere, aurora, the plasma torus, the Jovian plasma sheet and the Jovian aurora. The JUDE imaging and spectral channels are both designed to capture FUV lines from sulphur ions in the Io plasma torus. Finally, JUDE’s remote sensing capability offers an exciting opportunity to discover the Europa “plume” activity that may be present, through limb observations during flybys and from more distant observing locations. The Ganymede-focused and moon related science objectives will be addressed in the Ganymede orbit phase and during the multiple moon flybys, whilst the Jupiter science will be predominantly achieved during the Jupiter Equatorial Phases and during the high-inclination phase. The JUDE UV imager and spectrograph will produce discovery level science at Ganymede and the first true 2D UV images from Jupiter orbit. The exceptional JUICE trajectory affords many opportunities for breakthrough science discoveries in accordance with the SciRD; in addition to those, it provides unprecedented opportunities to directly witness the electromagnetic connection between Ganymede and Jupiter by making the first simultaneous UV observations of the respective atmospheres within the JUDE field-of-view. This is possible as a direct consequence of the JUDE true imaging capability. To successfully meet the science requirements outlined above, the JUDE ImaC has a spatial resolution of 20 arcsec over a circular field-of-view with 6˚ diameter, which allows a 100 km spatial resolution on Jupiter from Ganymede orbital distances (and 20 m resolution on Ganymede from 200 km, for example). JUDE’s ImaC mirrors and detector window will be covered with multilayer coatings which efficiently select a narrow bandpass from 130 to 143 nm, to allow measurements of the faint Oxygen lines at 130.4 nm and 135.6 nm in Ganymede’s (and other moon’s) atmosphere. This bandpass also allows observations of the SIV lines (between 140.5 and 142.4 nm) emitted within the Io plasma torus and in Io’s atmosphere. The bright Jovian emissions will also be suppressed within this bandpass which will necessarily limit the count rate to an acceptable level. The Ly-α line at 122 nm will be largely excluded as will the reflected sunlight longward of 150 nm. The sensitivity of the ImaC is 50 Rayleigh (at 3-sigma). The SpeC has a spectral resolution of 0.5 nm in order to meet the requirements of the SciRD, and has a field-of-view which is a 6˚ x 0.1˚ slit co-aligned with, and centred on, the ImaC circular field-of-view. The lower wavelength of the SpeC bandpass is set to ~110 nm in order to include the bright Ly-α line (useful to study the H corona) in a region of reduced transmission. The upper wavelength limit, ~195 nm, is such that transmission is slowly decreasing in the 180-195 nm spectral region, allowing measurements of the moon’s albedos beyond 165 nm, as well as the detection of compounds such as CO2, SO2, O2, O3, H2CO3 and H2O2 by comparing JUDE reflectance spectra to those obtained in laboratory studies. FUV emission lines from S and O are also observable within the bandpass and B-type stars emitting within this waveband will allow occultation experiments to be performed, to determine the composition and structure of the moon’s atmospheres and the detection of a possible Europa plume. The same is true for the Jovian atmosphere for which attenuation by H2 and hydrocarbons allows determination of the atmospheric structure. The sensitivity of the SpeC is 10 R/nm (at 3-sigma). The JUDE instrument channels: ImaC and the co-aligned SpeC, are both operating within the 110–195 nm range. Each channel has independent optics and detector elements, providing a level of redundancy such that loss of either imager or spectrograph does not constitute an entire loss of science. In contrast to more conventional (e.g. scanning or pushbroom) imaging spectrographs, JUDE can provide high time resolution (<1 second) high throughput images over a wide field of view (6° diameter) with no time variation across the field – a capability which is critical in gaining a better understanding of the complex dynamical processes taking place in the Jovian magnetosphere. The primary optic in each channel is a multilayer-coated mirror operating at normal incidence, with flight heritage in the form of the scan mirror in the Ultraviolet Spectrograph (UVS) now en-route to Jupiter onboard JUNO. The imaging channel uses a secondary mirror to of a similar type to focus the image onto the focal plane detector, while in the spectrograph channel, the secondary is a spherical, holographic grating. The spectrograph design is simple, with heritage in airglow spectrographs flown on terrestrial UV missions, and the Imaging UV Spectrograph for MAVEN. The grating element is produced by Jobin-Yvon, who have produced diffraction gratings for major missions including SOHO and HST. Each channel includes an identical microchannel plate (MCP) detector with the robust, radiation-tolerant performance required for a mission in the formidable environment of Jupiter. Such detectors are well proven, having flown on many missions including ROSAT (UoL heritage). They have also operated in the vicinity of Jupiter, in the focal plane of the UV spectrograph onboard the Voyager probes. The detector readout is a new type of capacitive division image charge readout (C-DIR; invented by Dr Jon Lapington) which offers, simultaneously, high spatial resolution and high count rate performance. Adaptive signal processing capabilities allow JUDE to accommodate the very wide dynamic range expected, from observations of Jupiter’s auroral ovals which emit with intensities of mega Rayleighs, to the weak (few tens of Rayleigh) emissions found at Ganymede. The readout structure is simple and robust, and has already been demonstrated in laboratory trials, while the electronics chain has its heritage in particle physics detectors, and has therefore been designed with radiation tolerance as a primary consideration. Pre-launch and in-flight calibrations will be implemented to assure that the JUDE data are suitable for quantitative scientific analysis. The proposed JUDE configuration successfully meets the scientific objectives of the JUICE mission. Our decision to implement an imaging channel instead of covering the MUV waveband increases the whole mission’s scientific output while remaining compliant with the MPDD. Due to its high-temporal resolution read-out system, JUDE is capable of producing volumes of data that are incompatible with the limited telemetry allocated to the UV instrument, even after a modest compression factor is applied. We therefore have proposed a mode of operation (the JUDE reference mode) which takes 1 minute snapshots over an observation opportunity (for example during a flyby sequence). Using this reference mode, and taking the maximum count rate estimates for the various targets, we find that the JUDE data volume is compliant with the tight allocation for the UV instrumentation of 40 GBytes/year The JUDE design presented in this proposal is above the mass allocation. We believe that all components of our design are necessary to reach the scientific goals of JUICE mission and that any major changes (such as the descope of a channel) will be at the considerable expense of the expected science return. However, further optimisation will be performed during the Phase A to bring JUDE into the allocated mass envelope while compromising its scientific return only slightly. We propose an efficient management structure with clearly delineated responsibilities. The Principal Investigator, Prof. Denis Grodent (Be) will take on the responsibilities as specified in the JUICE payload Announcement of Opportunity, supported closely by the Co-PI Dr Emma Bunce (UK) and by the team of Co-Investigators. The contribution of each country is represented by lead Co-Investigators: Prof. John Clarke (Boston University), Dr. Candy Hansen (PSI), and Dr Xianzhe Jia (University of Michigan), and Dr Nigel Bannister (UK) as CoI and Instrument Scientist (see Figure 1 below). The philosophy has been to assign well-defined tasks to each institute with an overall project manager to coordinate the efforts. The Consortium Project Manager (Etienne Renotte, CSL) will execute the managerial tasks relevant to the instrument development. The Product and Quality Assurance management will be implemented by all hardware contributors. Each consortium institute has a local project manager for their respective work packages, reporting to the Consortium Project Manager. The outreach potential of JUDE’s instantaneous wide field images is enormous. The potential PhD students of 2030 who we hope to educate and inspire with JUDE images and spectra are currently 3 years old; their supervisors are in secondary school. The team regards the educational aspects of the instrument and data as particularly important, and we plan a comprehensive JUDE/JUICE programme of outreach to schools and to the public, as part of the project and one which will be initiated upon selection. The national funding agency of Belgium serves as the Lead Funding Agency (LFA) for the JUDE instrument. The letters of endorsement from Belgium and United Kingdom are included in this proposal. Although the agencies endorse their respective national contributions, funding will be secured after the selection of the instrument proposal, according to the usual procedure. [less ▲]

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See detailUltrathin EUV Filters Testing and Characterization under High Flux (13 SC) for Solar Orbiter EUI Instrument
Jacques, Lionel ULg; Halain, Jean-Philippe ULg; Rossi, Laurence ULg et al

Conference (2011, October 07)

The test setup and characterization parameters of ultrathin EUV filters under high solar flux are presented. These 150nm thick aluminium filters are used at the entrance of the Extreme Ultraviolet Imager ... [more ▼]

The test setup and characterization parameters of ultrathin EUV filters under high solar flux are presented. These 150nm thick aluminium filters are used at the entrance of the Extreme Ultraviolet Imager (EUI) payload, which is developed at the Centre Spatial de Liège for the Solar Orbiter ESA M-class mission. The solar flux that they shall have to withstand will be as high as 13 solar constants when the spacecraft reach its 0.28AU perihelion. A specific design based on additional ribs has therefore been developed to enhance the thermal behaviour and heat evacuation while preserving its optical properties. It is essential to assess the design performances under the Solar Orbiter high solar flux. Therefore, thermal vacuum test under 13 solar constants will be performed. The filters temperature profiles will be measured during the tests through infrared imaging. A thermal correlation of the test will then be performed to deduce the filters actual thermal properties to be used in the global instrument geometrical and thermal mathematical models. [less ▲]

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See detailJUDE: A Far-UV Imager for JUICE
Grodent, Denis ULg; Bunce, Emma; Bannister, Nigel et al

Poster (2011, August 31)

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See detailA Far-UV Imager for the Jupiter Ganymede Orbiter
Bunce, E. J.; Molyneux, P.; Bannister, N. et al

Poster (2010, May 17)

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See detailThe technical challenges of the Solar-Orbiter EUI instrument
Halain, Jean-Philippe ULg; Rochus, Pierre ULg; Renotte, Etienne ULg et al

in Proceedings - Society of Photo-Optical Instrumentation Engineers (2010), 7732(26),

The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide EUV and Lyman-α images of the ... [more ▼]

The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of a suite of two high-resolution imagers (HRI) and one dual-band full Sun imager (FSI) that will provide EUV and Lyman-α images of the solar atmospheric layers above the photosphere. The EUI instrument is based on a set of challenging new technologies allowing to reach the scientific objectives and to cope with the hard space environment of the Solar Orbiter mission. The mechanical concept of the EUI instrument is based on a common structure supporting the HRI and FSI channels, and a separated electronic box. A heat rejection baffle system is used to reduce the Sun heat load and provide a first protection level against the solar disk straylight. The spectral bands are selected by thin filters and multilayer mirror coatings. The detectors are 10µm pitch back illuminated CMOS Active Pixel Sensors (APS), best suited for the EUI science requirements and radiation hardness. This paper presents the EUI instrument concept and its major sub-systems. The current developments of the instrument technologies are also summarized. [less ▲]

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See detailFirst light of SWAP on-board PROBA2
Halain, Jean-Philippe ULg; Defise, Jean-Marc ULg; Rochus, Pierre ULg et al

in Proceedings of SPIE (2010), 7732

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 ... [more ▼]

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 PTB-Bessy 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. [less ▲]

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See detailTHE EXTREME ULTRAVIOLET IMAGER (EUI) ONBOARD THE SOLAR ORBITER MISSION
Rochus, Pierre ULg; Halain, Jean-Philippe ULg; Renotte, Etienne ULg et al

in A3. 4. Space-based Astronomy (2009)

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See detailThe JWST MIRI Double-Prism, Design and Science Drivers
Fisher, Sebastian; Rossi, Laurence ULg; Renotte, Etienne ULg et al

in Proceedings of SPIE (2008, July 12), 7010

We present how it is achieved to mount a double prism in the filter wheel of MIRIM - the imager of JWST’s Mid Infrared Instrument. In order to cope with the extreme conditions of the prisms’ surroundings ... [more ▼]

We present how it is achieved to mount a double prism in the filter wheel of MIRIM - the imager of JWST’s Mid Infrared Instrument. In order to cope with the extreme conditions of the prisms’ surroundings, the low resolution double prism assembly (LRSDPA) design makes high demands on manufacturing accuracy. The design and the manufacturing of the mechanical parts are presented here, while ’Manufacturing and verification of ZnS and Ge prisms for the JWST MIRI imager’ are described in a second paper [1]. We also give insights on the astronomical possibilities of a sensitive MIR spectrometer. Low resolution prism spectroscopy in the wavelength range from 5-10 microns will allow to spectroscopically determine redshifts of objects close to/at the re-ionization phase of the universe. [less ▲]

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See detailManufacturing and verification of ZnS and Ge prisms for the JWST MIRI imager
Rossi, Laurence ULg; Renotte, Etienne ULg; Plesseria, Jean-Yves ULg et al

in Proceedings of SPIE (2008, June 23), 7018

The JWST Mid-Infrared Instrument (MIRI) is designed to meet the JWST science requirements for mid-IR capabilities and includes an Imager MIRIM provided by CEA (France). A double-prism assembly (DPA ... [more ▼]

The JWST Mid-Infrared Instrument (MIRI) is designed to meet the JWST science requirements for mid-IR capabilities and includes an Imager MIRIM provided by CEA (France). A double-prism assembly (DPA) allows MIRIM to perform low-resolution spectroscopy. The MIRIM DPA shall meet a number of challenging requirements in terms of optical and mechanical constraints, especially severe optical tolerances, limited envelope and very high vibration loads. <br />The University of Cologne (Germany) and the Centre Spatial de Liege (Belgium) are responsible for design, manufacturing, integration, and testing of the prism assembly. A companion paper (Fischer et al. 2008) is presenting the science drivers and mechanical design of the DPA, while this paper is focusing on optical manufacturing and overall verification processes. <br />The first part of this paper describes the manufacturing of Zinc-sulphide and Germanium prisms and techniques to ensure an accurate positioning of the prisms in their holder. (1) The delicate manufacturing of Ge and ZnS materials and (2) the severe specifications on the bearing and optical surfaces flatness and the tolerance on the prism optical angles make this process innovating. The specifications verification is carried out using mechanical and optical measurements; the implemented techniques are described in this paper. <br />The second part concerns the qualification program of the double-prism assembly, including the prisms, the holder and the prisms anti-reflective coatings qualification. Both predictions and actual test results are shown. [less ▲]

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See detailOMC: An Optical Monitoring Camera for INTEGRAL - Instrument description and performance
Mas-Hesse, J. M.; Gimenez, A.; Culhane, J. L. et al

in Astronomy and Astrophysics (2003), 411(1), 261-268

The Optical Monitoring Camera (OMC) will observe the optical emission from the prime targets of the gammaray instruments onboard the ESA mission INTEGRAL, with the support of the JEM-X monitor in the X ... [more ▼]

The Optical Monitoring Camera (OMC) will observe the optical emission from the prime targets of the gammaray 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 x 2048 pixels) working in frame transfer mode (1024 x 1024 pixels imaging area). With a field of view of 5degrees x 5degrees it will be able to monitor sources down to magnitude V = 18. Typical observations will perform a sequence of different integration times, allowing for photometric uncertainties below 0.1 mag for objects with V less than or equal to 16. [less ▲]

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See detailThe Herschel-PACS Grating Drive and its controller
Renotte, Etienne ULg; Callut, Eric ULg; Guiot, Marc ULg et al

(2003)

The Photodetector Array Camera and Spectrometer (PACS), on board the Herschel Space Observatory, is designed for imaging and spectroscopy in the wavelength region between 60 and 210 gm. This paper reports ... [more ▼]

The Photodetector Array Camera and Spectrometer (PACS), on board the Herschel Space Observatory, is designed for imaging and spectroscopy in the wavelength region between 60 and 210 gm. This paper reports the design of the grating cryogenic mechanism of the PACS spectrometer and its remote controller (DEC/MEC) located on the outside of the Herschel cryostat. The PACS grating shall be capable of accurate positioning (4 arcsec) within a large angular stroke (40 arcdeg) in cryogenic environment (4.2 K). Technologies of actuators, position sensors, pivots, dry lubricants, servo-control and cryogenic test set-up are presented. At the other end of the Herschel 10-meter high-impedance cryogenic harness, the DEC/MEC consists of DSP processor-based electronics that control and synchronise the cold focal plane mechanisms and infrared detector arrays. The DEC/MEC operates an on board software running under a real-time operating system. Technologies involved in the control electronics are discussed and correlated to validation tests conducted with actual hardwares. [less ▲]

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See detailThe IMAGE mission (NASA) : design, test and results from the far UV spectrographic Imager
Habraken, Serge ULg; Renotte, Etienne ULg; Jamar, Claude ULg et al

in Space scientific research in Belgium (Space Sciences) (2002)

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See detailA Test Cryostat for Herschel-PACS Mechanism
Renotte, Etienne ULg; Barzin, Pascal ULg; Guiot, Marc ULg et al

in SCHÜRMANN B. (Ed.) ESA-SP-467 (2001, September)

The PACS Grating Assembly consists of a flat ruled grating of 320x80 mm²; its positioning mechanism; and launch-locking system. The Grating Assembly is part of the PACS Focal Plane Unit (FPU) and is ... [more ▼]

The PACS Grating Assembly consists of a flat ruled grating of 320x80 mm²; its positioning mechanism; and launch-locking system. The Grating Assembly is part of the PACS Focal Plane Unit (FPU) and is operated at liquid helium temperature (4K). It is remote-controlled from the Detector & Mechanism Controller (DEC/MEC), which is located on the Herschel Service Module. The grating shall be capable of accurate positioning (4 arcsec) within a large angular throw (40 arcdeg) and restricted dissipation to the 4K heat sink (< 5 mW). The development of the Grating mechanism controller has urged the need for a cryogenic simulator of the Grating Assembly with regard to the large change in value of mechanical and electrical characteristics between room temperature and liquid helium temperature. The simulator consists of a functional prototype of the Grating Assembly and a dedicated helium cryostat with appropriate interfaces. The test cryostat is a homemade facility (CSL) designed to cool down the prototype (and subsequent models) to liquid helium temperature. The test set-up also provides relevant instrumentation such as cryogenic temperature read-out, electrical feedthroughs toward the payload and optical viewport. [less ▲]

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See detailStellar calibration of the WIC and SI imagers and the GEO photometers on IMAGE/FUV
Gladstone, G. R.; Mende, S. B.; Frey, H. U. et al

Poster (2000, December)

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See detailObservations of substorm auroras from the IMAGE spacecraft
Frey, H. U.; Mende, S. B.; Lampton, M. et al

Conference (2000, October)

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See detailFar ultraviolet imaging of the aurora: new directions
Mende, S. B.; Frey, H. U.; Lampton, M. et al

Conference (2000, October)

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See detailFar ultraviolet imaging from the IMAGE spacecraft. 1. System design
Mende, S. B.; Heetderks, H.; Frey, H. U. et al

in Space Science Reviews (2000), 91

Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora, the footprint of magnetospheric regions. To assure the simultaneity of these ... [more ▼]

Direct imaging of the magnetosphere by the IMAGE spacecraft will be supplemented by observation of the global aurora, the footprint of magnetospheric regions. To assure the simultaneity of these observations and the measurement of the magnetospheric background neutral gas density, the IMAGE satellite instrument complement includes three Far Ultraviolet (FUV) instruments. In the wavelength region 120-190 nm, a downward-viewing auroral imager is only minimally contaminated by sunlight, scattered from clouds and ground, and radiance of the aurora observed in a nadir viewing geometry can be observed in the presence of the high-latitude dayglow. The Wideband Imaging Camera (WIC) will provide broad band ultraviolet images of the aurora for maximum spatial and temporal resolution by imaging the LBH N_2 bands of the aurora. The Spectrographic Imager (SI), a monochromatic imager, will image different types of aurora, filtered by wavelength. By measuring the Doppler-shifted Ly-alpha, the proton-induced component of the aurora will be imaged separately. Finally, the GEO instrument will observe the distribution of the geocoronal emission, which is a measure of the neutral background density source for charge exchange in the magnetosphere. The FUV instrument complement looks radially outward from the rotating IMAGE satellite and, therefore, it spends only a short time observing the aurora and the Earth during each spin. Detailed descriptions of the WIC, SI, GEO, and their individual performance validations are discussed in companion papers. This paper summarizes the system requirements and system design approach taken to satisfy the science requirements. One primary requirement is to maximize photon collection efficiency and use efficiently the short time available for exposures. The FUV auroral imagers WIC and SI both have wide fields of view and take data continuously as the auroral region proceeds through the field of view. To minimize data volume, multiple images are taken and electronically co-added by suitably shifting each image to compensate for the spacecraft rotation. In order to minimize resolution loss, the images have to be distortion-corrected in real time for both WIC and SI prior to co-adding. The distortion correction is accomplished using high speed look up tables that are pre-generated by least square fitting to polynomial functions by the on-orbit processor. The instruments were calibrated individually while on stationery platforms, mostly in vacuum chambers as described in the companion papers. Extensive ground-based testing was performed with visible and near UV simulators mounted on a rotating platform to estimate their on-orbit performance. The predicted instrument system performance is summarized and some of the preliminary data formats are shown. [less ▲]

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