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The Ma_MISS spectrometer is integrated within the drilling system of the Rosalind Franklin ExoMars rover. This paper reports the on-ground calibration campaign performed on the spectrometer. Here, we focus on the spectral calibration of the instrument. The experimental setup used to carry out calibration is described, and the methods used for data processing and key parameters retrieval are explained. In particular, the spectral parameters such as (i) pixel central wavelengths, (ii) spectral response function, (iii) spectral resolution, (iv) sampling, and (v) range are determined. In a follow-up paper, the linearity and radiometric calibrations are described, while in De Sanctis et al. [Planet. Sci. J. 3, 142 (2022)], the validation of spectral measurements performed on synthetic and natural rock targets is presented.

The STereo imaging Channel (STC) is a double wide-angle camera developed to be one of the channels of the SIMBIO-SYS instrument onboard of the ESA BepiColombo mission to Mercury. STC main goal is to map in 3D the whole Mercury surface. The geometric and radiometric responses of the STC Proto Flight model have been characterized on-ground during the calibration campaign. The derived responses will be used to calibrate the STC images that will be acquired in flight. The aim is to determine the functions linking the detected signal in digital number to the radiance of the target surface in physical units. The result of the radiometric calibration consists in the determination of well-defined quantities: (1) the dark current as a function of the integration time and of the detector temperature, settled and controlled to be stable at 268 K; (2) the read out noise, which is associated with the noise signal of the read-out electronic; and (3) the fixed pattern noise, which is generated by the different response of each pixel. Once these quantities are known, the photon response and the photo-response non-uniformity, which represents the variation of the photon responsivity of a pixel in an array, can be derived. The final result of the radiometric calibration is the relation between the radiance of an accurately known and uniform source, and the digital numbers measured by the detector.

The Stereo Imaging Channel (STC) is one of the channels of the Spectrometer and Imagers for MPO BepiColombo Integrated Observatory SYStem (SIMBIO-SYS) onboard the ESA BepiColombo mission to Mercury. STC is a double wide-angle camera designed to image each portion of the Mercury surface from two different lines of sights, whose main aim is to provide panchromatic stereo-image pairs required to generate the Digital Terrain Model (DTM) reconstruction. In addition, selected surface areas will be acquired in color. This work presents the expected STC on-ground and in-flight performance describing the preliminary evaluation of some key parameters: the optical performance, the on-ground resolution and detector response, the achievable Signal to Noise Ratio (SNR) for different integration times and observation strategies and the global coverage of panchromatic filters during the entire scientific phase. The estimation of the SNR has been made using the STC radiometric model with Hapke reflectance model for Mercury surface and the SPICE toolkit software. The SPICE toolkit software with kernel for BepiColombo mission has been used also for the estimation of the on-ground pixel dimension and the global coverage all over the mission. (C) 2018 Elsevier Ltd. All rights reserved.

PLATO is an exoplanet hunting mission from the European Space Agency. It is a medium-class mission, with alaunch foreseen in 2026. Its prime objective is to uncover Earth-sized planets residing in the habitable zone of theirhost star. The payload consists of 26 cameras with a very wide field-of-view. While the operational temperatureof the cameras will be−80◦C, the focal plane of each camera will be integrated with its telescope assembly(bearing the optics) at room temperature. The degradation of the optical quality at ambient, combined with thedetector dark current and with the very high accuracy required from the alignment process bring a number ofinteresting challenges. In the present article, we review the alignment concept, present optical simulations of themeasurements at ambient along with their analysis, and present an error budget for the optical measurements.The derivation of this error budget is easily applicable to all optical measurements to be performed during thealignment, i.e. the definition of the best image plane at the operational temperature and the optical alignmentitself, at room temperature.

Full list of authors: Cremonese, G.; Capaccioni, F.; Capria, M. T.; Doressoundiram, A.; Palumbo, P.; Vincendon, M.; Massironi, M.; Debei, S.; Zusi, M.; Altieri, F.; Amoroso, M.; Aroldi, G.; Baroni, M.; Barucci, A.; Bellucci, G.; Benkhoff, J.; Besse, S.; Bettanini, C.; Blecka, M.; Borrelli, D.; Brucato, J. R.; Carli, C.; Carlier, V.; Cerroni, P.; Cicchetti, A.; Colangeli, L.; Dami, M.; Da Deppo, V.; Della Corte, V.; De Sanctis, M. C.; Erard, S.; Esposito, F.; Fantinel, D.; Ferranti, L.; Ferri, F.; Ficai Veltroni, I.; Filacchione, G.; Flamini, E.; Forlani, G.; Fornasier, S.; Forni, O.; Fulchignoni, M.; Galluzzi, V.; Gwinner, K.; Ip, W.; Jorda, L.; Langevin, Y.; Lara, L.; Leblanc, F.; Leyrat, C.; Li, Y.; Marchi, S.; Marinangeli, L.; Marzari, F.; Mazzotta Epifani, E.; Mendillo, M.; Mennella, V.; Mugnuolo, R.; Muinonen, K.; Naletto, G.; Noschese, R.; Palomba, E.; Paolinetti, R.; Perna, D.; Piccioni, G.; Politi, R.; Poulet, F.; Ragazzoni, R.; Re, C.; Rossi, M.; Rotundi, A.; Salemi, G.; Sgavetti, M.; Simioni, E.; Thomas, N.; Tommasi, L.; Turella, A.; Van Hoolst, T.; Wilson, L.; Zambon, F.; Aboudan, A.; Barraud, O.; Bott, N.; Borin, P.; Colombatti, G.; El Yazidi, M.; Ferrari, S.; Flahaut, J.; Giacomini, L.; Guzzetta, L.; Lucchetti, A.; Martellato, E.; Pajola, M.; Slemer, A.; Tognon, G.; Turrini, D. -- This is an open access article, The SIMBIO-SYS (Spectrometer and Imaging for MPO BepiColombo Integrated Observatory SYStem) is a complex instrument suite part of the scientific payload of the Mercury Planetary Orbiter for the BepiColombo mission, the last of the cornerstone missions of the European Space Agency (ESA) Horizon + science program. The SIMBIO-SYS instrument will provide all the science imaging capability of the BepiColombo MPO spacecraft. It consists of three channels: the STereo imaging Channel (STC), with a broad spectral band in the 400-950 nm range and medium spatial resolution (at best 58 m/px), that will provide Digital Terrain Model of the entire surface of the planet with an accuracy better than 80 m; the High Resolution Imaging Channel (HRIC), with broad spectral bands in the 400-900 nm range and high spatial resolution (at best 6 m/px), that will provide high-resolution images of about 20% of the surface, and the Visible and near-Infrared Hyperspectral Imaging channel (VIHI), with high spectral resolution (6 nm at finest) in the 400-2000 nm range and spatial resolution reaching 120 m/px, it will provide global coverage at 480 m/px with the spectral information, assuming the first orbit around Mercury with periherm at 480 km from the surface. SIMBIO-SYS will provide high-resolution images, the Digital Terrain Model of the entire surface, and the surface composition using a wide spectral range, as for instance detecting sulphides or material derived by sulphur and carbon oxidation, at resolutions and coverage higher than the MESSENGER mission with a full co-alignment of the three channels. All the data that will be acquired will allow to cover a wide range of scientific objectives, from the surface processes and cartography up to the internal structure, contributing to the libration experiment, and the surface-exosphere interaction. The global 3D and spectral mapping will allow to study the morphology and the composition of any surface feature. In this work, we describe the on-ground calibrations and the results obtained, providing an important overview of the instrument performances. The calibrations have been performed at channel and at system levels, utilizing specific setup in most of the cases realized for SIMBIO-SYS. In the case of the stereo camera (STC), it has been necessary to have a validation of the new stereo concept adopted, based on the push-frame. This work describes also the results of the Near-Earth Commissioning Phase performed few weeks after the Launch (20 October 2018). According to the calibration results and the first commissioning the three channels are working very well. © 2020, The Author(s)., We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0. The SIMBIO-SYS instrument has been developed by Leonardo under ASI contract I/054/10/0.

Leonardo has been involved in the realization of several infrared payloads for Earth observation since 1990. Among the currently in-orbit operative instruments are the two Sea and Land Surface Temperature Radiometers (SLSTRs) and PRISMA (PRecursore IperSpettrale della Missione Applicativa, meaning Hyperspectral Italian Pre-cursor of Operational mission). The SLSTRs are high-accuracy radiometers that provide sea surface temperature data continuity with respect to previous (A)ATSRs in order to serve climatology over the next 20 years, and exist within the framework of the European Space Agency Sentinel-3 mission, which is part of the Copernicus program. The PRISMA program is the first Agenzia Spaziale Italiana optical hyperspectral mission for Earth observation. It is based on a high spectral resolution spectrometer operating in the visible-short wave infrared channels optically integrated with a panchromatic camera.

The STereoscopic imaging Channel (STC) is one of the three channels of SIMBIO-SYS instrument, whose goal is to study the Mercury surface in visible wavelength range. The SIMBIO-SYS instrument is on-board of ESA Bepicolombo spacecraft. STC is a double wide angle camera designed to map in 3D the whole Mercury surface. The detector of STC has been equipped with six filters: two panchromatic and four broad band. The panchromatic filters are centred at 700 nm with 200 nm of bandwidth, while the broad band ones have bandwidth of 20 nm and are centred at 420, 550, 750 and 920 nm, respectively. In order to verify the relative spectral response of each STC sub-channel, a spectral calibration has to be performed during the on-ground calibration campaign. The result consists in the transmissivity curve of each filter of STC as function of wavelength. The camera has been illuminated with a monochromator coupled with a diffuser and a collimator. The images have been acquired by changing the wavelength of the monochromator in the range correspondent to the filter bandwidth. The background images have been obtained by covering the light source and have been used to calculate and subtract the dark signal, fixed pattern noise (FPN) and ambient effects.

The ESA-JAXA mission BepiColombo toward Mercury will be launched in October 2018. On board of the European module, MPO (Mercury Planetary Orbiter), the remote sensing suite SIMBIOSYS will cover the imaging demand of the mission. The suite consists of three channels dedicated to imaging and spectroscopy in the spectral range between 420 nm and 2 ?m. STC (STereo Imaging Channel) will provide the global three-dimensional reconstruction of the Mercury surface with a vertical accuracy better than 80 m and, as a secondary scientific objective, it will operate in target oriented mode for the acquisition of multi spectral images with a spatial scale of 65 m along-track at the periherm for the first orbit at Mercury. STC consists in 2 sub-channels looking at the Mercury surface with an angle of ±20° with respect to the nadir direction. Most of the optical elements and the detector are shared by the two STC sub-channels and to satisfy the scientific objectives six filters strips are mounted directly in front of the sensor. An off-axis and unobstructed optical configuration has been chosen to enhance the imaging contrast capabilities of the instrument and to allow to reduce the impact of the ghosts and stray light. The scope of this work is to present the on-ground geometric calibration pipeline adopted for the STC instrument. For instruments dedicated to 3D reconstruction, a careful geometric calibration is important, since distortion removal has a direct impact on the registration and the mosaicking of the images. The definition of the distortion for off-axis optical configuration is not trivial, this fact forced the development of a distortion map model based on the RFM (rational function model). In contrast to other existing models, which are based on linear estimates, the RFM is not specialized to any particular lens geometry, and is sufficiently general to model different distortion types, as it will be demonstrated.

PRISMA (PRecursore IperSpettrale della Missione Applicativa) is an Italian Satellite Earth Observation hyperspectral mission led by the Italian Space Agency (ASI) and planned for the launch in 2018. The payload is based on a high spectral resolution imaging spectrometer operating in the VNIR/SWIR (0.4-2.5 µm) optically integrated with a medium resolution Panchromatic camera (0.4-0.7 µm). The PRISMA Ground Segment includes the Mission Control Centre (MCC) and the Satellite Control Centre (SCC) both located at the Fucino station and the Instrument Data Handling System (IDHS) located at the ASI Space Geodesy Center in Matera. The IDHS is devoted to process the payload data downloaded using the X-Band antenna of the CNM (National Multimission Center). The IDHS data processing function generates Level 0, Level 1 and Level 2 products archived and distributed by the CNM. This paper defines the detailed PRISMA product types, specifying the content and process of the products generation.

The Stereo Imaging Channel (STC) is a double wide angle camera designed to image each portion of the Mercury surface from two different perspectives, providing panchromatic stereo-image pairs required for the Digital Terrain Model (DTM) reconstruction. In addition, selected surface areas will be acquired in color. STC is one of the channels of Spectrometer and Imagers for MPO BepiColombo-Integrated Observatory SYStem. In this work we evaluate the STC Signal to Noise Ratio (SNR) for different observation strategies and for the different phases of the BepiColombo mission. The estimation of the SNR is obtained using the radiometric model developed for SIMBIO-SYS, which takes into account the Hapke reflectance model for Mercury surface.

BepiColombo, an European Space Agency (ESA) mission being conducted in cooperation with the Japan space agency, will explore Mercury with a set of eleven instruments onboard the spacecraft Mercury Planetary Orbiter (MPO). Among them, SIMBIO-SYS (Spectrometers and Imagers for MPO BepiColombo Integrated Observatory SYStem) is a complex instrument that will provide images and spectra in the 400–2000 nm wavelength range of the entire surface of Mercury. Pre-flight calibration of the SYMBIO-SYS instrument is mandatory for reliable scientific interpretation of images and spectra returned from the planet Mercury. This paper presents the calibration device designed and implemented for the specific requirements of this instrument. It mainly consists of a thermal vacuum chamber simulating the space environment, an optical bench collecting calibration sources and optical elements that simulate the conditions of Mercury observations, mechanical interfaces used for positioning the three channels inside the vacuum chamber, thermal interfaces to explore the operating temperatures, computer interfaces that allow to communicate with both the instrument and the calibration elements and synchronize the calibrations sequences with the status of the calibration device. As the major goal is the characterization of the radiometric performances of the three channels of SIMBIO-SYS, radiometric performances of the test setup evaluated by simulations and measurements are emphasized.

The Stereo Channel (STC) is a double wide-angle camera developed to be one of the channels of the SIMBIO-SYS instrument onboard of the ESA BepiColombo mission to Mercury. STC main goal is to map in 3D the whole Mercury surface. The geometric and radiometric responses of the STC Proto Flight model have been characterized on-ground during the calibration campaign. The derived responses will be used to calibrate the STC images that will be acquired in flight. The aim is to derive the functions that link the detected signal in digital number to the radiance of the target surface in physical units. The result of the radiometric calibration consists in the determination of well-defined quantities: i) the dark current as a function of the integration time and of the detector temperature, nominally fixed at 268 K; ii) the Read Out Noise, which is associated with the noise signal of the read-out electronic; iii) the Fixed Pattern Noise, which is generated by the different response of each pixel; iv) once these quantities are known, the photon response and the Photo Response Non-uniformity, which represent the variation of the photon-responsivity of a pixel in an array, can be derived. The final result of the radiometric calibration is the relation between the radiance of an accurately known and uniform source, and the digital numbers measured by the detector.

BepiColombo is the first ambitious, multi-spacecraft mission of ESA/JAXA to Mercury. It will be launched in October 2018 from Kourou, French Guiana, starting a 7-year journey, which will bring its modules to the innermost planet of the solar system. The Stereo Camera (STC) is part of the SIMBIO-SYS instrument, the Italian suite for imaging in visible and near infrared which is mounted on the BepiColombo European module, i.e. the Mercury Planetary Orbiter (MPO). STC represents the first push-frame stereo camera on board of an ESA satellite and its main objective is the global three-dimensional reconstruction of the Mercury surface. The harsh environment around Mercury and the new stereo acquisition concept adopted for STC pushed our team to conceive a new design for the camera and to carry out specific calibration activities to validate its photogrammetric performance. Two divergent optical channels converging the collected light onto a unique optical head, consisting in an off-axis telescope, will provide images of the surface with an on-ground resolution at periherm of 58 m and a vertical precision of 80 m. The observation strategies and operation procedures have been designed to optimize the data-volume and guarantee the global mapping considering the MPO orbit. Multiple calibrations have been performed on-ground and they will be repeated during the mission to improve the instrument performance: the dark side of the planet will be exploited for dark calibrations while stellar fields will be acquired to perform geometrical and radiometric calibrations.

We report about the measurement of the Noise- Equivalent Spectral Radiance (NESR) of the VIHI imaging spectromter aboard ESA's Bepi Colombo mission to Mercury. The knowledge of the NESR allows to determine the capability of an optical detector to measure faint signals. A description of the setup used to determine the NESR during the prelaunch calibration campaign is given. The processing of the data col- lected at various operative temperatures and integration times is described. The sensitivity study of the NESR has been performed at the expected detector's temperatures and integration times with the goal to determine the minimum spectral radiance at which VIHI is sensitive during the different observation phases of the mission. A simulation of the expected Signal-to-Noise Ratio (SNR) of VIHI during the different orbital phases is provided.

CHEOPS is the first small class mission adopted by ESA in the framework of the Cosmic Vision 2015-2025. Its launch is foreseen in early 2019. CHEOPS aims to get transits follow-up measurements of already known exo-planets, hosted by near bright stars (V

The STereo imaging Channel (STC) is the first push-frame stereo camera on board an European Space Agency (ESA) satellite, i.e., the ESA-Japan Aerospace eXploration Agency mission BepiColombo. It was launched in October 2018, and it will reach its target, Mercury, in 2025. The STC main aim is to provide the global three-dimensional reconstruction of the Mercury surface. STC, the stereo channel of spectrometer and imagers for Mercury Planetary Orbiter BepiColombo-Integrated Observatory System, is based on an original optical design that incorporates the advantages of a compact unique detector instrument and the convenience of a double direction acquisition system. In fact, STC operates in a push-frame imaging mode and its two optical sub-channels will converge the incoming light on a single focal plane assembly allowing to minimize mass and volume. The focal plane of the instrument is housing six different filters: two panchromatic filters in the range 600-800 nm and four broadband filters with central wavelengths in the range 420-920 nm. In this paper, the geometrical calibration of the instrument, including the optical setups used, will be described. The methods used to derive the focal lengths, the boresights, and the reference systems of the different filter models are presented, and the related distortion results are discussed. The STC off-axis configuration forced to develop a distortion map model based on the RFM (rational function model). In contrast to other existing models, which allow linear estimates, the RFM is not referred to specific lens geometry, but it is sufficiently general to model a variety of distortion types, as it will be demonstrated in this particular case. Published under license by AIP Publishing.

In the framework of the ESA-JAXA BepiColombo mission to Mercury, the global mapping of the planet will be performed by the on-board Stereo Camera (STC), part of the SIMBIO-SYS suite [1]. In this paper we propose a new technique for the validation of the 3D reconstruction of planetary surface from images acquired with a stereo camera. STC will provide a three-dimensional reconstruction of Mercury surface. The generation of a DTM of the observed features is based on the processing of the acquired images and on the knowledge of the intrinsic and extrinsic parameters of the optical system. The new stereo concept developed for STC needs a pre-flight verification of the actual capabilities to obtain elevation information from stereo couples: for this, a stereo validation setup to get an indoor reproduction of the flight observing condition of the instrument would give a much greater confidence to the developed instrument design. STC is the first stereo satellite camera with two optical channels converging in a unique sensor. Its optical model is based on a brand new concept to minimize mass and volume and to allow push-frame imaging. This model imposed to define a new calibration pipeline to test the reconstruction method in a controlled ambient. An ad-hoc indoor set-up has been realized for validating the instrument designed to operate in deep space, i.e. in-flight STC will have to deal with source/target essentially placed at infinity. This auxiliary indoor setup permits on one side to rescale the stereo reconstruction problem from the operative distance in-flight of 400 km to almost 1 meter in lab; on the other side it allows to replicate different viewing angles for the considered targets. Neglecting for sake of simplicity the Mercury curvature, the STC observing geometry of the same portion of the planet surface at periherm corresponds to a rotation of the spacecraft (SC) around the observed target by twice the 20° separation of each channel with respect to nadir. The indoor simulation of the SC trajectory can therefore be provided by two rotation stages to generate a dual system of the real one with same stereo parameters but different scale. The set of acquired images will be used to get a 3D reconstruction of the target: depth information retrieved from stereo reconstruction and the known features of the target will allow to get an evaluation of the stereo system performance both in terms of horizontal resolution and vertical accuracy. To verify the 3D reconstruction capabilities of STC by means of this stereo validation set-up, the lab target surface should provide a reference, i.e. should be known with an accuracy better than that required on the 3D reconstruction itself. For this reason, the rock samples accurately selected to be used as lab targets have been measured with a suitable accurate 3D laser scanner. The paper will show this method in detail analyzing all the choices adopted to lead back a so complex system to the indoor solution for calibration.

Small-dimension, low-mass spectrometers are useful for both Earth observation and planetary missions. A very compact multi-spectral mini-spectrometer that contains no moving parts, can be constructed combining a graded-thickness filter, having a spatially variable narrow-band transmission, to a CCD array detector. The peak wavelength of the transmission filter is moving along one direction of the filter surface, such that each line of a two-dimensional array detector, equipped with this filter, will detect radiation in a different pass band. The spectrum of interest for image spectrometry of the Earth surface is very wide, 400-1000nm. This requirement along with the need of a very small dimension, makes this filter very difficult to manufacture. Preliminary results on metal-dielectric wedge filters, with a gradient of the transmission peak wavelength equal to 60nm/mm, are reported. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.

BepiColombo is one of the cornerstone missions of the European Space Agency dedicated to the exploration of the planet Mercury and it is expected to be launched in July 2016. One of the BepiColombo instruments is the STereoscopic imaging Channel (STC), which is a channel of the Spectrometers and Imagers for MPO BepiColombo Integrated Observatory SYStem (SIMBIOSYS) suite: an integrated system for imaging and spectroscopic investigation of the Mercury surface. STC main aim is the 3D global mapping of the entire surface of the planet Mercury during the BepiColombo one year nominal mission. The STC instrument consists in a novel concept of stereocamera: two identical cameras (sub-channels) looking at ±20° from nadir which share most of the optical components and the detector. Being the detector a 2D matrix, STC is able to adopt the push-frame acquisition technique instead of the much common push-broom one. The camera has the capability of imaging in five different spectral bands: one panchromatic and four intermediate bands, in the range between 410 and 930 nm. To avoid mechanisms, the technical solution chosen for the filters is the single substrate stripe-butted filter in which different glass pieces, with different transmission properties, are glued together and positioned just in front of the detector. The useful field of view (FoV) of each sub-channel, though divided in 3 strips, is about 5.3° x 3.2°. The optical design, a modified Schmidt layout, is able to guarantee that over all the FoV the diffraction Ensquared Energy inside one pixel of the detector is of the order of 70-80%. To effectively test and calibrate the overall STC channel, an ad hoc Optical Ground Support Equipment has been developed. Each of the sub-channels has to be separately calibrated, but also the data of one sub-channel have to be easily correlated with the other one. In this paper, the experimental results obtained by the analysis of the data acquired during the preliminary onground optical calibration campaign on the STC Flight Model will be presented. This analysis shows a good agreement between the theoretical expected performance and the experimental results.

The optical design of the Stereoscopic Imaging Channel for the Bepicolombo ESA mission will be presented. The design solutions will be described and the expected results will be compared to the ones measured on the flight model during the on-ground calibration.

Before integration aboard European Space Agency BepiColombo mission to Mercury, the visible and near infrared hyperspectral imager underwent an intensive calibration campaign. We report in Paper I about the radiometric and linearity responses of the instrument including the optical setups used to perform them. Paper II [F. Altieri et al., Rev. Sci. Instrum. 88, 094503 (2017)] will describe complementary spectral response calibration. The responsivity is used to calculate the expected instrumental signal-to-noise ratio for typical observation scenarios of the BepiColombo mission around Mercury. A description is provided of the internal calibration unit that will be used to verify the relative response during the instrument's lifetime. The instrumental spatial response functions as measured along and across the spectrometer's slit direction were determined by means of spatial scans performed with illuminated test slits placed at the focus of a collimator. The dedicated optical setup used for these measurements is described together with the methods used to derive the instrumental spatial responses at different positions within the 3 . 5 ° field of view and at different wavelengths in the 0.4-2.0 μm spectral range. Finally, instrument imaging capabilities and Modulated Transfer Function are tested by using a standard mask as a target.

The Dawn spectrometer (VIR) is a hyperspectral spectrometer with imaging capability. The design fully accomplishes Dawn’s scientific and measurement objectives. Determination of the mineral composition of surface materials in their geologic context is a primary Dawn objective. The nature of the solid compounds of the asteroid (silicates, oxides, salts, organics and ices) can be identified by visual and infrared spectroscopy using high spatial resolution imaging to map the heterogeneity of asteroid surfaces and high spectral resolution spectroscopy to determine the composition unambiguously. The VIR Spectrometer—covering the range from the near UV (0.25 μm) to the near IR (5.0 μm) and having moderate to high spectral resolution and imaging capabilities—is the appropriate instrument for the determination of the asteroid global and local properties. VIR combines two data channels in one compact instrument. The visible channel covers 0.25–1.05 μm and the infrared channel covers 1–5.0 μm. VIR is inherited from the VIRTIS mapping spectrometer (Coradini et al. in Planet. Space Sci. 46:1291–1304, 1998; Reininger et al. in Proc. SPIE 2819:66–77, 1996) on board the ESA Rosetta mission. It will be operated for more than 2 years and spend more than 10 years in space.

The ESA-JAXA mission BepiColombo that will be launched in 2018 is devoted to the observation of Mercury, the innermost planet of the Solar System. SIMBIOSYS is its remote sensing suite, which consists of three instruments: the High Resolution Imaging Channel (HRIC), the Visible and Infrared Hyperspectral Imager (VIHI), and the Stereo Imaging Channel (STC). The latter will provide the global three dimensional reconstruction of the Mercury surface, and it represents the first push-frame stereo camera on board of a space satellite. Based on a new telescope design, STC combines the advantages of a compact single detector camera to the convenience of a double direction acquisition system; this solution allows to minimize mass and volume performing a push-frame imaging acquisition. The shared camera sensor is divided in six portions: four are covered with suitable filters; the others, one looking forward and one backwards with respect to nadir direction, are covered with a panchromatic filter supplying stereo image pairs of the planet surface. The main STC scientific requirements are to reconstruct in 3D the Mercury surface with a vertical accuracy better than 80 m and performing a global imaging with a grid size of 65 m along-track at the periherm. Scope of this work is to present the on-ground geometric calibration pipeline for this original instrument. The selected STC off-axis configuration forced to develop a new distortion map model. Additional considerations are connected to the detector, a Si-Pin hybrid CMOS, which is characterized by a high fixed pattern noise. This had a great impact in pre-calibration phases compelling to use a not common approach to the definition of the spot centroids in the distortion calibration process. This work presents the results obtained during the calibration of STC concerning the distortion analysis for three different temperatures. These results are then used to define the corresponding distortion model of the camera.

The SPectral IMager (SPIM) facility is a laboratory visible infrared spectrometer developed to support space borne observations of rocky bodies of the solar system. Currently, this laboratory setup is used to support the DAWN mission, which is in its journey towards the asteroid 1-Ceres, and to support the 2018 Exo-Mars mission in the spectral investigation of the Martian subsurface. The main part of this setup is an imaging spectrometer that is a spare of the DAWN visible infrared spectrometer. The spectrometer has been assembled and calibrated at Selex ES and then installed in the facility developed at the INAF-IAPS laboratory in Rome. The goal of SPIM is to collect data to build spectral libraries for the interpretation of the space borne and in situ hyperspectral measurements of planetary materials. Given its very high spatial resolution combined with the imaging capability, this instrument can also help in the detailed study of minerals and rocks. In this paper, the instrument setup is first described, and then a series of test measurements, aimed to the characterization of the main subsystems, are reported. In particular, laboratory tests have been performed concerning (i) the radiation sources, (ii) the reference targets, and (iii) linearity of detector response; the instrumental imaging artifacts have also been investigated. © 2015 AIP Publishing LLC.

In the context of a stereo-camera, measuring the image quality allows to define the accuracy of the 3D reconstruction. In fact, depending on the precision of the camera position data, on the kind of reconstruction algorithm, and on the adopted camera model, it determines the vertical accuracy of the reconstructed terrain model. Aim of this work is to describe the results and the method implemented to determine the Line Spread Function (LSF) of the Stereoscopic Channel (STC) of the SIMBIOSYS imaging system for the BepiColombo mission. BepiColombo is the cornerstone mission n.5 of the European Space Agency dedicated to the exploration of the innermost planet of the Solar System, Mercury, and it is expected to be launched in 2016. STC is a double push-frame single-detector camera composed by two identical sub-channels looking at ±21° wrt the nadir direction. STC has been designed so to have many optical elements common to both sub-channels. Also the image focal plane is common to the sub-channels and this permits the use of a single detector for the acquisition of the two images, i.e. one for each viewing direction. Considering the novelty of the design, conceived to sustain a harsh environment and to be as compact as possible, the STC unit is very complex. To obtain the most accurate 3D reconstruction of the Mercury surface, a camera model as precise as possible is needed, and an ad-hoc calibration set-up has been designed to calibrate the instrument both from the usual geometrical and radiometrical points of view and more specifically for the instrument stereo capability. In this context LSF estimation was performed with a new method applying a particular oversampling approach for the curve fitting to determine at first the entire calibration system transfer function and at the end the optical properties of the single instrument.

SIMBIOSYS is a highly integrated instrument suite that will be mounted on-board BepiColombo, which is the fifth cornerstone mission of the European Space Agency dedicated to the exploration of the planet Mercury and it is expected to be launched in 2016. The SIMBIOSYS instrument consists of three channels: the STereo imaging Channel (STC), with broad spectral bands in the 400–950 nm range and medium spatial resolution (up to 50 m/px); the High Resolution Imaging Channel (HRIC), with broad spectral bands in the 400–900 nm range and high spatial resolution (up to 5 m/px), and the Visible and near- Infrared Hyperspectral Imaging channel (VIHI), with high spectral resolution (up to 6 nm) in the 400–2000 nm range and spatial resolution up to 100 m/px. The on-ground calibration system has to cover the full spectral range of the instrument, i.e. from 400 to 2000 nm, and the emitted radiance has to vary over a range of four decades to account for both simulations of Mercury surface acquisition and star field observations. The methods and the results of the measurements done to calibrate the integrating sphere needed for the on-ground radiometric testing of the SIMBIOSYS instrument will be given and discussed. Temporal stability, both on short and long periods, spatial and spectral uniformity, and the emitted radiance for different lamp configurations and different shutter apertures have been measured. The results of the data analysis confirm that the performance of the integrating sphere is well suited for the radiometric calibration of all the three different channels of the SIMBIOSYS instrument.

This paper reports the design, assembly and calibration activities relative to the internal calibration unit mounted on the Visible and Infrared Hyperspectral Imager (VIHI). VIHI is one of the three optical channels of the SIMBIO-SYS suite (Spectrometers and Imagers for MPO BepiColombo Integrated Observatory SYStem), one of the payload instruments onboard the probe BepiColombo/MPO, the ESA cornestone mission to be launched in 2016-2017 to Mercury. The activities reported include also the qualification tests of the commercial sources (a Welch-Allyn 1163 incandescence lamp and the NICHIA NJSW036BLT LED) selected. All the qualifications (Thermal, Vibration and Radiation tests) were successful, demonstrating the suitability of the commercial sources as Flight hardware. The performances of the ICU were verified during its mounting and alignment in the VIHI optical bench. The ICU satisfy the requirements of providing a spectral radiance of the same order of magnitude of the signal from Mercury and of guaranteeing a good degree of spatial uniformity across the spectrometer slit for the verification of the flat field in flight. The LED source provide an uniformity of the order of 10%, while the lamp signal drops by about 30% at the extreme edges of the FOV.

The authors present the tradeoff and the merit criteria that lead to the selection of the M. Brunn [1] "un obscured four mirrors based telescope" as the collimator of the Optical Ground Support Equipment in the frame of the Assembly Integration and Verification (AIV) activities forecast for the optical characterization of the High Resolution Camera (HRIC) on board of the Simbio-sys mission to Mercury, instrument currently under development and manufacturing at Selex Galileo (SG) facilities in its Florence site. Several optical configurations have been accounted for the design and manufacturing of the three meters focal length, diffraction limited and wide field of view (0.4X0.6 degs) toolkit. From the classical un obscured systems such as the aspheric solution based onto two hyperbolic mirror, working under an f - number of 13.6, the Brunn solution revealed excellent optical quality free from coma, astigmatism and spherical aberration accomplished by an ultra compact design in within a volume of 1.2x1.0 x0.5 cubic meters and other basic advantages such as the relative easy way in aligning and manufacturing the mirrors.

Compact spectrometers are of interest for space applications for both Earth observation and analysis of planet soil. The spectrometer here described is dedicated to Land imaging and is based on the use of linear variable filters for wavelength selection. This kind of filter is able to transmit the radiation in a narrow band (

The Linearly Variable Filters (LVF) are complex optical devices that, integrated in a CCD, can realize a «single chip spectrometer». In the framework of an ESA Study, a team of industries and institutes led by SELEX-Galileo explored the design principles and manufacturing techniques, realizing and characterizing LVF samples based both on All-Dielectric (AD) and Metal-Dielectric (MD) Coating Structures in the VNIR and SWIR spectral ranges. In particular the achieved performances on spectral gradient, transmission bandwidth and Spectral Attenuation (SA) are presented and critically discussed. Potential improvements will be highlighted. In addition the results of a feasibility study of a SWIR Linear Variable Filter are presented with the comparison of design prediction and measured performances. Finally criticalities related to the filter-CCD packaging are discussed. The main achievements reached during these activities have been: - to evaluate by design, manufacturing and test of LVF samples the achievable performances compared with target requirements; - to evaluate the reliability of the projects by analyzing their repeatability; - to define suitable measurement methodologies. © Copyright SPIE.

International audience; The limited knowledge about the majority of the Mercury surface leaves many open questions regarding its geological evolution, the anomalously high metal/silicate ratio, the magnetic field generation and exosphere evolution. An integrated suite of instruments, Spectrometer and Imagers for MPO BepiColombo-Integrated Observatory SYStem (SIMBIO-SYS), which includes a stereo imaging system (STC), a high-resolution imager (HRIC) and a visible-near-infrared imaging spectrometer (VIHI), has been selected for the ESA BepiColombo mission to Mercury. SIMBIO-SYS will scan the hermean surface with the three channels and map the physical, morphological, tectonic and compositional properties of the entire planet. The availability of high-resolution images will unveil details of specific target at an unprecedented resolution. The main scientific objectives and performances along with technical characteristics of SIMBIO-SYS are described in this paper.

For characterisation of non-uniform thin film coatings optical measurements should be performed with spatial resolution often much higher than that of conventional spectrophotometers. Here we present two different instruments constructed for transmittance and reflectance measurement of spatially non-uniform coatings. One of the setups is based on localized light distribution with a help of calibrated apertures, mapping needing sample displacement, while the other setup acquires the sample map ‘at-once’ with a CCD camera, spatial resolution being given by the pixel size. The spatial resolution ranges from 100 P m up to 2 mm for the first instrument, and is 30 P m for the second one. The spectral resolution of the first setup is about 0.5 nm in the range from 400 nm to 1700 nm, while for the second instruments it is 0.1 nm in the range 400-1000 nm. Besides the real optical performance of an optical device in terms of its spatially variable transmission and reflection, a ‘mapping’ of the thickness and refractive index of a single layer coating can be achieved. Comparison of the results obtained with these two instruments is given for two examples of coatings. The proposed instruments are useful tools for characterisation of both intended and undesired non-uniformity of optical coatings. Keywords : non-uniform thin film, spectroscopy, spatially resolved measurement

The selection of the Venus Express mission by ESA in 2002 was the occasion to propose the VIRTIS imaging spectrometer for the payload of this mission to Venus. After the discovery of the infrared windows in the near infrared from ground based observations in the 80ies, it was realized that the surface of Venus is accessible to infrared observation on the night side of Venus. Imaging spectroscopy in the visible and near infrared is therefore a powerful tool to study the Venus atmosphere down to its deepest levels. VIRTIS, the imaging spectrometer of the Rosetta mission (Coradini et al, 1998), as the second generation instrument of this kind after the Phobos/ISM (Bibring et al, 1989), Galileo/NIMS (Carlson et al, 1990) Mars Express/OMEGA (Bibring et al, 2004) and Cassini/VIMS (Brown et al, 2000), is perfectly fitted for extensive observations of the infrared and visible spectral images of Venus, with its unique combination of mapping capabilities at low spectral resolution (VIRTIS-M channel) and high spectral resolution slit spectroscopy (VIRTIS-H channel).

Direito e Justi��a, v. 18 n. 1 (2004)

The authors have retrospectively studied 18 cases of tibiocalcaneal arthrodesis performed to treat a fixed equinovarus deformity of the foot in 13 adult patients. The operations were performed between 1981 and 1998; there were 9 neurologic and 9 post-traumatic deformities. The mean calcaneal varus deformity was 50 degrees and the mean equinus deformity was 75 degrees. The results were evaluated using Kitaoka's criteria. We noted one postoperative cutaneous necrosis, two nonunions, one of which was reoperated by bone freshening and osteotomy of the midfoot. All rearfeet were in neutral alignment and were stable. Shortening was on average 2.8 cm. Plantar support was achieved in 10 feet, with improved autonomy, walking capacity and footwear. Overall, there were 10 good, 2 fair and 1 poor result. In the group with neurologic deformities there were 4 good, 1 fair and 1 poor result. In the group with post-traumatic deformities, there were 6 good and one fair results. Other series published also showed satisfactory results comparable to or better than those obtained with triple arthrodesis, which generates severe stiffness of the rear- and midfoot, disturbing gait. Fixed equinovarus deformity of the foot in the adult is a good indication for tibiocalcaneal arthrodesis, allowing in the majority of cases to achieve stable and painless plantar support.

The Visible Infrared Mapping Spectrometer--Visible Channel (VIMS-V) has been designed to produce high resolution multispectral images, in the optical waveband, of different planetary bodies. VIMS-V, presently under test, has been developed by Officine Galileo on behalf of the Agenzia Spaziale Italiana (Italian Space Agency) and will cover the spectral range from 300nm to 1050nm. This range will allow the detailed investigation of the mineralogy of Saturn satellites surfaces, searching for those components capable of affecting their evolution; studies of Saturn and Titan cloud structure and haze layers by identifying chemical components; searches for lighting and analysis their spectra. Light weight, thermal stability, and capability to operate with different mission scenarios have been the imposed design criteria of the instrument. Two further versions of VIMS-V are presently under study: one for a cometary mission and the other for a lunar detailed exploration mission.

The VIMS-V is a passive remote sensing instrument under development for the Italian Space Agency to perform high resolution spectral imaging in the optical waveband. Its unique design relies substantially on conventional materials and fabrication techniques to obtain high sensitivity and versatility in a compact, lightweight, and low power instrument suitable for deep space missions. The prototype will fly on the Cassini spacecraft and operate in unison with the Jet Propulsion Laboratory's IR channel to map the surface spatial distribution of mineral and chemical species of Saturn, its rings, and its satellites.

After having considered the spectral and geometrical performances of the Rosetta/VIRTIS-M experiment, we complete here the analysis by evaluating quantitatively the flat-field and radiometric responses. The purpose of this work is to retrieve the flat-field matrix necessary to homogenize the focal plane response. Moreover, the most important result is the determination of the instrument transfer function that allows to convert digital numbers in physical units of spectral radiance (Wm−2μm−1sterad−1). The strategy adopted to organize measurement sequence, a basic description of the on-ground experimental setups and the analysis of the collected data, is included in this article. An analysis of the instrumental stability has been performed as well by examining how the internal calibration data are affected by environmental conditions. These data allow to evaluate the cumulative effects of thermal and vibrational stresses on the instrumental performances: up to now we have verified that this effect is neglig...

The complete characterization of complex imaging spectrometers, such as VIRTIS-M (visual infrared thermal imaging spectrometer) aboard the Rosetta mission, requires a detailed and prolonged activity starting with the instrument integration and continuing during the entire operational life of the experiment. In this article we report the main experimental activities realized during the on-ground characterizations to evaluate the spectral and geometric performances in order to check the conformance with the technical requirements derived from the scientific goals of the experiment. Spectral calibrations allow to confirm instrumental spectral range, resolution, and sampling; geometric calibrations are necessary to estimate the pixel and slit functions, field of view extension, and possible optical aberrations. Two separate sections are dedicated to each one of these subjects, including the strategy followed to prepare measurements, a basic description of the on-ground experimental setups, and the analysis of the collected data.