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The Perseverance rover (Mars 2020 mission, NASA) is exploring the mineral diversity within Jezero, the host crater of a paleolake, and is searching for potential biosignatures and past habitability evidence. Amongst its science payload, the SuperCam instrument (LANL/USA and a consortium of French laboratories) plays a central role in the Mars habitability investigation by providing rapid, synergistic, fine-scale mineralogy, chemistry, and color imaging [1]. In particular, it carries the first near-infrared spectrometer, IRS, to be operated on the Martian surface. IRS is a miniaturized point spectrometer (~1.15 mrad field of view) located in the SuperCam’s mast unit. Its spectral range (1.3 – 2.6 µm range) covers major silicate and hydrated mineral absorption features [2]. The instrument has been fully calibrated on ground before its launch [3] but flight measurements are necessary to check and refine its instrumental response after the cruise, entry, descent and landing. During the first 90 sols, observations of the SuperCam Calibration Targets (SCCT) were routinely performed in alternance with scientific targets.An opportunistic observation of the Mastcam-Z calibration target has also been acquired. The IRS sensitivity, measured on the White SCCT, appears to be generally compliant with the ground measurements, except at short wavelengths (Fig. 1). Flight calibrated measurements of the other SCCTs are compliant with their lab reference (Fig. 2) within 5 to 20 % for the Red and Cyan, but the evaluation of the absolute reflectance of the Black SCCT is far from expected, perhaps due to the ambient light misestimation. The calibration also consists in the removal of instrumental and environmental parasitic effects: CO 2 absorptions caused by the path of light through the Martian atmosphere are removed by dividing by a simulated spectrum of the gas; an EMI/EMC effect causing “glitches” in the AOTF’s RF power supply as well as in acquired data is mitigated by a specific detection algorithm; and readout spikes are eliminated by a statistical algorithm as well. Finally, datasets are cosmetically cleaned using higher level refinement algorithms (wavelets filtering and polynomial smoothing of the dark) to enhance band depth contrast without introducing significant biases. The remaining uncertainty on reflectance absolute level is mainly attributed to the error on the geometry of the illumination which requires a better modeling of local opography and the atmosphere diffusion. Some low frequency residuals are also miscalibrated by the current pipeline and still under investigation (e.g., RF power stability, thermal effects). Notwithstanding these calibration uncertainties, the instrument signal to noise ratio (SNR) is high enough, and the relative (i.e., spectral channel to spectral channel) calibration is precise enough to be sensitive to faint spectral features (down to a few percent band depth) even if few parts of the spectral range show very faint but high frequency effects. Thus we will present the assessment of the radiometric in-flight performance of the instrument and the evaluation of the detection threshold for specific spectral signatures. Figure 1: Radiometric instrument transfer function derived from ground calibration (blue) and flight measurements (orange), showing their divergence at short wavelength. Figure 2: Color SCCTs measurement performed on Sol 77. The lighter lines correspond to the lab reference of these calibration targets. References[1] Wiens, R.C. et al., 2017. Spectroscopy; [2] Fouchet et al., 2015, 46 th LPSC; [3] Royer et al., 2020, RScI

International audience; The Perseverance rover (Mars 2020 mission, NASA) landed in the ancient lakebed of Jezero crater, Mars on February 18th, 2021. The main science objectives of the mission are the characterization of past habitable environments, the search for preserved biosignatures and the collection of samples to be returned to Earth by the next MSR (Mars Sample Return, NASA/ESA) mission [1]. The payload includes the SuperCam instrument (under the leadership of LANL, USA and IRAP, France), which plays a critical role in the exploration strategy, as it combines various remote-sensing techniques to investigate the elemental and mineralogical composition of rocks and soils: high-resolution color imaging, laser-induced breakdown spectroscopy, Raman spectroscopy, visible and near-infrared (VISIR) reflectance spectroscopy, and acoustic sensing [2, 3, 4, 5]. In particular, the near-infrared spectrometer is a novel instrument on the Martian surface. The spectra, together with data from two additional visible spectrometers, cover 0.39-0.85 µm (VIS) and 1.3-2.6 µm (IR), which allows the identification of a wide variety of minerals.Figure 1. Enhanced-color mosaic of images taken by the Mastcam-Z Left camera of the rover workspace on sol 78 [6]. NASA/Caltech-JPL/MSSS/ASU. Orbital data show that the landing site exhibits diverse mineralogical assemblages in various geological contexts, attesting in particular of an ancient aqueous activity during the Noachian and Hesperian eras (> 3 Ga), and including mafic minerals, carbonates, phyllosilicates and opaline silica [7, 8, 9].We present the initial results of the SuperCam VISIR spectrometers, with calibrated [10] spectral data collected in the first months of operation of the instrument, with a focus on the rocks and soils present in the rover workspace and explored so far. Spectra have been obtained on nearby rocks so far within 50 m of the Octavia E. Butler landing site, at the boundaries of the Crater Floor Fractured Rough (CF-Fr) and Crater Floor Fractured (CF-F) units, which from orbit exhibit the spectral signatures of pyroxene and olivine, respectively [7]. A comparison with orbital data is presented in [11].Most of the rocks analyzed in the close vicinity of the rover so far consists of light-toned `pavers' and upstanding dark-toned rocks (Fig. 1). Some variability in reflectance levels and absorption bands is observed within and between the rocks (Fig. 2), but overall they share similar spectral characteristics in the VISIR. In particular, they all exhibit an absorption band near 1.9 µm (a spectral signature indicating the presence of the water molecule), a band that is usually not observed in the soils - at least not with the same depth. This absorption near 1.9 µm is also present in spectral observations of outcrops a few kilometers away from the rover [11]. In addition to this absorption at ~1.9 µm, a blue slope in the 2.1-2.5 µm region and subtle absorption bands near 1.4 µm and 2.28 µm show up locally, which suggests the presence of hydrated mineral species, such as an iron-rich phyllosilicate (like nontronite or hisingerite), potentially mixed with an oxy-hydroxide such as ferrihydrite (Fig. 2). The intensity of these absorption bands is consistent with at least a few weight percent of these hydrated species in the observed target, either in the bulk of the rock or in a varnish/coating. Finally, fewer spectra exhibit a weak absorption at 2.2 µm, suggesting the additional presence of an Al-OH or Si-OH-bearing phase. Overall, the detection of these widespread hydration features supports some pervasive water-rock interactions during the past, in the landing site of Perseverance. CRISM data suggest that we have landed in a relatively low hydration region, and that the rover will be driving through progressively increasing hydration throughout the mission, as it moves onto the delta, the olivine-carbonate and the region outside of Jezero crater. Future in situ measurements on these potentially more hydrated and diverse rocks are expected to bring new insights into the past aqueous environment at Jezero crater.Figure 2. Example of a SuperCam observation on a rock present in the workspace of the rover: 10x1 raster on target Bidziil. (a) RMI mosaic taken at 2.3 m from the rover mast on sol 56 with the IRS 68% field of view annotated in red. (b) Corresponding IRS spectra in color, compared to laboratory spectra of known minerals in black and grey. References[1] Farley, K. A. et al., 2020. Space Sci. Rev.; [2] Wiens, R.C. et al., 2017. Spectroscopy; [3] Maurice, S. et al., 2021 Space Sci. Rev.; [4] Cousin, A. et al., this conference; [5] Chide, B. et al., this conference; [6] Bell, J. F. et al., 2021. Space Sci. Rev. [7] Goudge, T. A. et al., 2015. J. Geophys. Res. Planets; [8] Ehlmann, B. L. et al., 2008. Science; [9] Tarnas, J. D. et al., 2019. Geophys. Res. Lett.; [10] Royer, C. et al., this conference; [11] Quantin-Nataf et al., this conference.

The Martian Moon Explorer (MMX) is a sample return JAXA mission that is devoted to the exploration of the Mars system. MMX will be launched in 2024, inserted into Mars orbit in 2025, and will investigate the martian system during 3 years, focusing mainly on Phobos, the principal target of the mission. The main goals of MMX are to return samples of Phobos, and, throughout both the in situ detailed investigation of Mars satellites and the further laboratory studies of Phobos samples on Earth, to clarify the origin of the Mars satellites and the process of planets formation in the Solar System. Observations of Mars will also be performed to investigate its evolution history and its atmosphere. To reach these goals, MMX has a complex onboard instrumentation including imaging systems, infrared, neutron and gamma-ray spectrometers, a lidar, a mass spectrum analyzer, a dust monitoring instrument, and a rover for in situ investigation, beside the sampling and retrieval devices. We present in this work the design and performances of the MMX InfraRed Spectrometer (MIRS), which is an imaging spectrometer operating between 0.9 - 3.6 microns. MIRS is provided by CNES and built at LESIA-Paris Observatory in collaboration with four other French laboratories (LAB, LATMOS, LAM, IRAP-OMP), and in close collaboration with JAXA and MELCO. MIRS is a spectrometer that uses the push-broom acquisition principle. A single detector acquisition (2D matrix) provides the image of a strip in one direction (spatial), and the spectrum of each point of the strip in the second direction (spectral). The second spatial dimension results from the motion of MIRS Line of Sight in the along-track direction either thanks to the spacecraft speed or by actuation of a scanner mounted on the instrument, which allows ± 20° of optical amplitude respect to the boresight. The optical design includes a telescope with two free form mirrors focusing the target on the entrance slit of the spectrometer, a collimator, a low-density groove grating working at first order, and a couple of dioptric objectives. The first one projects the spectral image on a filter that sorts the grating orders. The second one projects this spectral image on the detector, but also images the pupil on a cold stop in order to limit the background flux due to the thermal emission of the spectrometer. The detector is a hybrid CMOS made of 500 columns by 256 lines with square pixels of 30 µm pitch, sensitive from 0.45 to 3.8 µm. Both the detector and the cold stop are encapsulated in a cryostat and cooled down to 110 K. A shutter is placed in the slit plane in order to close the spectrometer cavity after the telescope and acquire background images that can be subtracted to science data. The instrument includes also a front cover to limit dust pollution when landing on Phobos, as well as an internal calibration lamp. The MIRS field of view (FOV) is ≥ ±1.65°. MIRS will observe Phobos and Deimos in the 0.9-3.6 μm range with a spectral resolution better than 20 nm and with a spatial resolution of 0.35 mrad/px. For Phobos, MIRS will acquire spectra at SNR > 100 up to 3.2 micron in about 2 seconds of integration time for observations carried out at phase angle of 30°. The spatial resolution is of 13-30 m/px during the Quasi Satellite Orbit-Medium global survey (altitude varying from 37 to 84 km), down to meter to sub-meter for the selected sampling sites candidates or the sampling spot. The spectral radiometric absolute accuracy is expected to be of 10%, and the relative accuracy of 1%. Thanks to the large wavelength coverage and high SNR, MIRS will detect faint absorption features associated to minerals and materials that will help in understanding the satellite origin and composition, like anhydrous and/or hydrated silicates, water ice and organic matter, if any. The high SNR and the unprecedented spatial resolution achieved by MIRS will permit to fully characterize the composition and mineralogy of Phobos and Deimos, and to further investigate the local compositional heterogeneity associated with the different geomorphological features across Phobos surface. MIRS will also study Mars atmosphere, in particular the spatial and temporal changes such as clouds, dust and water vapor.

Martian Moon eXploration (MMX) mission by Japan Aerospace Exploration Agency (JAXA) is the third Japanese sample return mission. One of the main mission goals is to decipher the origin of these moons, which will provide important clues on planetary formation and how water is delivered to inner planets. MMX will be launched in September 2024 to Martian system to bring back samples from Phobos conducting detailed observations of Phobos and Deimos, and monitoring Mars’s climate. The mission is five-year round trip with return sample on Earth on July 2029. The spacecraft will arrive to Mars system on August 2025, stay three years, and have QSO (Quasi Satellite Orbits) around Phobos at different altitudes to select the landing sampling sites. The spacecraft will land for several hours on the Phobos surface to collect at least 10g of Phobos regolith using a corer going down to a depth of at least 2cm. MMX may collect Phobos samples in two different sites. After three years the spacecraft will leave the Martian system and return the samples to Earth, completing the first round-trip to the Martian system. The principal objectives of the mission are: To settle the controversy on the origin of the Martian moons by close-up observations and return sample analysis To constrain processes for planetary formation and material transport in the region connecting the inner and outer solar systems To reveal evolutionary processes of the Martian system in the circum-Martian environments A set of mission instruments are defined and under development to achieve the major mission goals. The included instruments are: the wide-angle camera OROCHI (Optical RadiOmeter composed of CHromatic Imagers), the telescopic (narrow-angle) camera TENGOO (TElescopic Nadir imager for GeOmOrphology), the laser altimeter LIDAR (Light Detection and Ranging), CMDM (Circum-Martian Dust Monitor), MSA (Mass Spectrum Analyzer), MEGANE (Gamma rays and Neutrons Spectrometer) provided by NASA, a near-infrared spectrometer MIRS (MMX InfraRed Spectrometer) provided by CNES, SMP sampling device and the sample return capsule. A small Rover (total weight less than 30kg) developed by CNES and DLR is also a part of the mission. The Rover payload includes four scientific instruments: a IR radiometer (miniRAD), a Raman spectrometer (RAX), a stereo pair of cameras looking forward (NavCAM) and two cameras looking at the interface wheel-surface (WheelCAM) and consequent Phobos’ regolith mechanical properties. ESA will participate to the mission assisting with deep space communication equipment. 1. MIRS MIRS instrument is built at LESIA-Paris Observatory in collaboration with four other French laboratories (LAB, LATMOS, LAM, IRAP-OMP), with collaboration and financial support of CNES and close collaboration with JAXA and MELCO. MIRS is an imaging spectrometer in the 0.9 - 3.6 microns spectral band with spectral resolution better than 20 nm. The IFOV is 0.35 mrad and FOV of +/-1.65°. The SNR is higher than 100 up to 3.2 µm in a maximum integration time less than 2s. The detector has dimension of 256 x 256 pixels with pixel pitch of 30 microns. The total mass is lower than 11.9 kg (including 20% margin), and the volume of complete instrument is about 320 x 150 x 400 mm3. 2. MIRS science objectives MIRS is expected to characterize Phobos and Deimos surfaces and Mars atmospheric composition by remotely identifying diagnostic features in the near-infrared range. MIRS is used to achieve some of the mission-requirements, in particular: 1: To grasp the surface distribution of the constituent materials of Phobos. Hydrous minerals and other related minerals should be identified and characterized spectroscopically for main parts of the full body in correspondence with its topography (at horizontal spatial resolutions of 20 m or better) and in a radius of 50 m or more around the sampling point (at spatial resolutions of 1 m or better). For the global areas, MIRS is expected to spectroscopically measure water (ice) (absorption band at 3.0-3.2 μm) and hydrous silicate minerals (features at 2.7-2.8 μm) at the wavelength resolutions (wavelength width) of 20 nm, S/N ratios > 100 and a spatial resolution of 20 m (for +/-30° latitude). The spectral radiometric absolute accuracy is expected to be of 10%, and the relative accuracy of 1%. If possible, also to measure organic matter (3.3.-3.5 μm) and hydrous/anhydrous silicate minerals (1.0 μm). An area within 50 m from a selected sampling spot at 1 m resolution will be also mapped. 2: To grasp the distribution of constituent materials of Deimos, from spectroscopic information, clarify the surface distribution of hydrous minerals and other related minerals corresponding to its topography at characteristic parts of the moon with a horizontal spatial resolution of 100 m or better. MIRS is expected to spectroscopically map major regions of Deimos at a spatial resolution better than 100 m for major absorption bands as observed in Phobos. 3: To constrain transport processes for dust and water near the Martian surface, continuous observations of the mid- to low-latitude distributions of dust storms, ice clouds, and water vapor in the Martian atmosphere are performed from high altitudes equatorial orbit in different seasons to within 1-hour time resolutions. MIRS is expected to perform observations of distributions of total amount of water vapor columns at 10 km spatial resolutions and spectral radiometric absolute accuracy of 10%, and spectral radiometric relative accuracy of 1% with temporal resolution less than 1-hour for the mid- to low-latitude selected areas. These observations are expected to be performed over several successive days in different seasons. 3. Conclusions MIRS will allow compositional characterization of Phobos, Deimos and temporal characterization of particular phenomena of Mars atmosphere. It will be also a fundamental instrument to evaluate sampling site candidates and support the selection of the two sampling sites on the Phobos surface. The mission will be able to clarify the origin of the Martian moons and may also be able to elucidate the process of the evolution of the Mars environment. Acknowledgements MMX is under developed and built by JAXA, with contributions from CNES, DLR and NASA. We thank the MMX JAXA teams for their efforts in defining and building the mission. The MIRS team thanks CNES for the financial support and collaboration to build MIRS instrument.

In mid-2019, the SuperCam instrument was installed aboard NASA's Mars 2020 rover, which is scheduled for launch in July 2020 and a landing at Jezero crater in February 2021. SuperCam is a collaboration between Los Alamos National Laboratory (LANL; the lead institution) and the Institut de Recherche en Astrophysique et Planetologie (IRAP), funded by the French Space Agency (CNES) and with contributions by universities and laboratories in France, Spain, and Denmark. SuperCam integrates a number of observation techniques into a single instrument, which builds on the design heritage of ChemCam, a laser induced breakdown spectroscopy (LIBS) instrument aboard the Curiosity rover. While retaining ChemCam's LIBS mode, SuperCam adds a remote Raman spectroscopy mode, an infrared spectrometer (IR), a microphone, and improves upon ChemCam's greyscale context imager with a color imager. This paper will give a broad overview of the SuperCam instrument, which is divided into three portions: the LANL-built SuperCam Body Unit (SCBU), the French-built SuperCam Mast Unit (SCMU), and the Spanish-built SuperCam Calibration Target (SCCT). The instrument operational modes will be detailed, explaining how the instrument as a whole is used to collect and process its data within the context of the Mars 2020 rover. Next, we will detail LANL's design, integration, and testing of the SCBU. The SCBU is installed inside the rover's body and features an optical demultiplexer feeding a set of three spectrometers, which are digitized by three charge-coupled devices (CCDs) from e2v, controlled by a low-noise spectrometer electronics module. The longest-wavelength visible-range spectrometer employs high-throughput transmission optics and an image intensifier to amplify and electronically gate the incoming light in Raman mode. This transmission spectrometer is powered and controlled by a high voltage power supply, designed and built at LANL. A low voltage power supply converts rover power to voltages used by the instrument. The command and data handling (C&DH) module features a Leon-3-based processor and a field programmable gate array for custom logic, along with a memory array. Instrument flight software architecture will be presented, with a focus on the body unit and mast unit functionality divide. The test qualification scheme will be detailed, with information on instrument optical performance testing.

International audience; The SuperCam instrument on the Perseverance Mars 2020 rover uses a pulsed 1064 nm laser to ablate targets at a distance and conduct laser induced breakdown spectroscopy (LIBS) by analyzing the light from the resulting plasma. SuperCam LIBS spectra are preprocessed to remove ambient light, noise, and the continuum signal present in LIBS observations. Prior to quantification, spectra are masked to remove noisier spectrometer regions and spectra are normalized to minimize signal fluctuations and effects of target distance. In some cases, the spectra are also standardized or binned prior to quantification. To determine quantitative elemental compositions of diverse geologic materials at Jezero crater, Mars, we use a suite of 1198 laboratory spectra of 334 well-characterized reference samples. The samples were selected to span a wide range of compositions and include typical silicate rocks, pure minerals (e.g., silicates, sulfates, carbonates, oxides), more unusual compositions (e.g., Mn ore and sodalite), and replicates of the sintered SuperCam calibration targets (SCCTs) onboard the rover. For each major element (SiO2, TiO2, Al2O3, FeOT, MgO, CaO, Na2O, K2O), the database was subdivided into five "folds" with similar distributions of the element of interest. One fold was held out as an independent test set, and the remaining four folds were used to optimize multivariate regression models relating the spectrum to the composition. We considered a variety of models, and selected several for further investigation for each element, based primarily on the root mean squared error of prediction (RMSEP) on the test set, when analyzed at 3 m. In cases with several models of comparable performance at 3 m, we incorporated the SCCT performance at different distances to choose the preferred model. Shortly after landing on Mars and collecting initial spectra of geologic targets, we selected one model per element. Subsequently, with additional data from geologic targets, some models were revised to ensure results that are more consistent with geochemical constraints. The calibration discussed here is a snapshot of an ongoing effort to deliver the most accurate chemical compositions with SuperCam LIBS.

The development of the planetary exploration for landers makes it more and more necessary to have at our disposal small and light instruments. This is why we are developing in our laboratory a light imaging spectrometer with a wedge filter making the spectral splitting. This design already developed in other laboratories has the great advantage to need a limited number of optical components. However its drawback is that at a given instant the different spectral pixels don’t see the same spot in the field. We propose a new design to remedy this drawback by the adjunction of a dispersive system in the fore-optics.

The issues related to moving elements in space and instruments working in broader wavelength ranges lead to a need for robust polarimeters, efficient on a wide spectral domain, and adapted to space conditions. As part of the UVMag consortium, created to develop spectropolarimetric UV facilities in space, such as the Arago mission project, we present an innovative concept of static spectropolarimetry. We studied a static and polychromatic method for spectropolarimetry, applicable to stellar physics. Instead of modulating the polarization information temporally, as usually done in spectropolarimeters, the modulation is performed in a spatial direction, orthogonal to the spectral one. Thanks to the proportionality between phase retardance imposed by a birefringent material and its thickness, birefringent wedges can be used to create this spatial modulation. The light is then spectrally cross-dispersed, and a full-Stokes determination of the polarization over the whole spectrum can be obtained with a single-shot measurement. The use of Magnesium Fluoride wedges, for example, could lead to a compact, static polarimeter working at wavelengths from 0.115 mm up to 7 mm. We present the theory and simulations of this concept, as well as laboratory validation and a practical application to Arago., Comment: Article accepted for publication in Applied Optics on 20 July 2015

The Exoplanet Characterisation Observatory, EChO, is a dedicated space mission to investigate the physics and chemistry of Exoplanet atmospheres. Using the differential spectroscopy by transit method, it provides simultaneously a complete spectrum in a wide wavelength range between 0.4μm and 16μm of the atmosphere of exoplanets. The payload is subdivided into 6 channels. The mid-infrared channel covers the spectral range between 5μm and 11μm. In order to optimize the instrument response and the science objectives, the bandpass is split in two using an internal dichroic. We present the opto-mechanical concept of the MWIR channel and the detector development that have driven the thermal and mechanical designs of the channel. The estimated end-to-end performance is also presented.

Nowadays, astronomers want to observe gaps in exozodiacal disks to confirm the presence of exoplanets, or even make actual images of these companions. Four hundred and fifty years ago, Jean-Dominique Cassini did a similar study on a closer object: Saturn. After joining the newly created Observatoire de Paris in 1671, he discovered 4 of Saturn's satellites (Iapetus, Rhea, Tethys and Dione), and also the gap in its rings. He made these discoveries observing through the best optics at the time, made in Italy by famous opticians like Giuseppe Campani or Eustachio Divini. But was he really able to observe this black line in Saturn's rings? That is what a team of optical scientists from Observatoire de Paris - LESIA with the help of Onera and Institut d'Optique tried to find out, analyzing the lenses used by Cassini, and still preserved in the collection of the observatory. The main difficulty was that even if the lenses have diameters between 84 and 239 mm, the focal lengths are between 6 and 50 m, more than the focal lengths of the primary mirrors of future ELTs. The analysis shows that the lenses have an exceptionally good quality, with a wavefront error of approximately 50 nm rms and 200 nm peak-to-valley, leading to Strehl ratios higher than 0.8. Taking into account the chromaticity of the glass, the wavefront quality and atmospheric turbulence, reconstructions of his observations tend to show that he was actually able to see the division named after him., 11 pages, 14 figures, proceedings of the SPIE conference Optics+Photonics, San Diego 2013

International audience; In this paper, we present the design of the MWIR channels of EChO. Two channels cover the 5-11 micron spectral range. The choice of the boundaries of each channel is a trade-off driven by the science goals (spectral features of key molecules) and several parameters such as the common optics design, the dichroic plates design, the optical materials characteristics, the detector cut-off wavelength. We also will emphasize the role of the detectors choice that drives the thermal and mechanical designs and the cooling strategy.

CoRoT and Kepler have brought a new and deep experience in long-term photometric surveys and how to use them. This is true for exoplanets characterizing, stellar seismology and beyond for studying several other phenomena, like granulation or activity. Based on this experience, it has been possible to propose new generation projects, like TESS and PLATO, with more specific scientific objectives and more ambitious observational programs in terms of sky coverage and/or duration of the observations. In this context and as a prospective exercise, we explore here the possibility to set up an all-sky survey optimized for seismic indices measurement, providing masses, radii and evolution stages for half a million solar-type pulsators (subgiants and red giants), in our galactic neighborhood and allowing unprecedented stellar population studies.

International audience

The Corot project, developed in the framework of the CNES small satellite program with a wide European cooperation, will be launched in 2006. It is dedicated to seismology and detection of telluric planets. It will perform relative photometry in visible light, during very long (150 days) observing runs in the same direction. Both programs are running simultaneously and about 50.000 stars will be observed during the 3 years life. The concept of the instrument is based on an off-axis telescope (27 cm pupil, 3° square field of view), a dioptric objective images the stars on a focal plane. The focal plane is made of 4 CCDs, 2k*4k pixels, AIMO and frame transfer, at -40°C, two for each scientific programs. Electronics boxes manage the CCD readout, the thermal control and house-keeping, onboard software makes pre-processing and data reduction. As the expected signal is made of very small fluctuations expressed in ppm (part per million) a specific calibration of all the photometric chain and sub-systems is necessary. We have developed a specific test bench to calibrate CCDs. The manufacturer (E2V) provided us 10 CCDs and we realized calibration tests on them to be able to choose 4 CCDs for the flight focal plane (with different optimizations for the two scientific programs). Thereafter the camera sub-system has been integrated and calibrated on a specific test bench. This sub-system is made of a dioptric objective, focal plane, electronics boxes, mechanical and thermal equipment. We will present the camera sub-system (constraints and design), the test bench, and the results of the different tests : CCD calibration, radiation effects, Focal-Plane integration, optical setup, thermal balance and Camera calibration.