HYPSOS (HYPerspectral Stereo Observing System, patented) is a novel remote sensing instrument able to extract the spectral information from the two channels of a pushbroom stereo camera; thus it simultaneously provides 4D information, spatial and spectral, of the observed features. HYPSOS has been designed to be a compact instrument, compatible with small satellite applications, to be suitable both for planetary exploration as well for terrestrial environmental monitoring. An instrument with such global capabilities, both in terms of scientific return and needed resources, is optimal for fully characterizing the observed surface of investigation. HYPSOS optical design couples a pair of folding mirrors to a modified three mirror anastigmat telescope for collecting the light beams from the optical paths of the two stereo channels; then, on the telescope focal plane, there is the entrance slit of an imaging spectrograph, which selects and disperses the light from the two stereo channels on a bidimensional detector. With this optical design, the two stereo channels share the large majority of the optical elements: this allowed to realize a very compact instrument, which needs much less resources than an equivalent system composed by a stereo camera and a spectrometer. To check HYPSOS actual performance, we realized an instrument prototype to be operated in a laboratory environment. The laboratory setup is representative of a possible flight configuration: the light diffused by a surface target is collimated on the HYPSOS channel entrance apertures, and the target is moved with respect to the instrument to reproduce the in-flight pushbroom acquisition mode. Here we describe HYPSOS and the ground support equipment used to characterize the instrument, and show the preliminary results of the instrument alignment activities.
The HYPerspectral Stereo Observing System (HYPSOS) is a novel remote sensing pushbroom instrument able to give simultaneously both 3D spatial and spectral information of the observed features. HYPSOS is a very compact instrument, which makes it attractive for both possible planetary observation and for its use on a nanosat, e.g. for civilian applications. This instrument collects light from two different perspectives, as a classical pushbroom stereocamera, which allows to realize the tridimensional model of the observed surface, and then to extract the spectral information from each resolved element, thus obtaining a full 4-dimensional hypercube dataset. To demonstrate the actual performance of this novel type of instrument, we are presently realizing a HYPSOS prototype, that is an instrument breadboard to be tested in a laboratory environment. For checking its performance, we setup an optical facility representative of a possible flight configuration. In this paper we provide a description of HYPSOS concept, of its optomechanical design and of the ground support equipment used to characterize the instrument. An update on the present status of the experiment is finally given.
On December 2018, the Near Earth Commissioning Phase (NECP) has been place forSIMBIO-SYS (Spectrometers and Imagers for MPO BepiColombo Integrated Observatory – SYStem), the suite part of the scientific payload of the BepiColombo ESA-JAXA mission. SIMBIO-SYS is composed of three channels: the high resolution camera (HRIC), the stereo camera (STC) and the Vis/NIR spectrometer (VIHI) . During the NECP the three channels have been operated properly. For the three channels were checked the operativity and the performance. The commanded operations allowed to verify all the instrument functionalities demonstrating that all SIMBIO-SYS channels and subsystems work nominally. During this phase we also validated the Ground Segment Equipment (GSE) and the data analysis tools developed by the team.
The BepiColombo mission represents the cornerstone n.5 of the European Space Agency (ESA) and it is composed of two satellites: the Mercury Planetary Orbiter (MPO) realized by ESA and the Mercury Magnetospheric Orbiter (MMO) provided by the Japan Aerospace Exploration Agency (JAXA). The payload of the MPO is composed by 11 instruments. About half of the entire MPO data volume will be provided by the Spectrometer and Imagers for MPO BepiColombo Integrated Observatory System" (SIMBIO-SYS) instrument suite. The SIMBIO-SYS suite includes three imaging systems, two with stereo and high spatial resolution capabilities, which are the Stereoscopic Imaging Channel (STC) and High Resolution Imaging Channel (HRIC), and a hyper-spectral imager in the Vis-NIR range, named Visible and near Infrared Hyper-spectral Imager (VIHI). In order to test and predict the instrument performances, a radiometric model is needed. It consists in a tool that permits to know what fraction of the incoming light is measured by the detector. The obtained signal depends on the detector properties (such as quantum efficiency and dark current) and the instrument transmission characteristics (transmission of lenses and filter strips, mirrors reflectivity). The radiometric model allows to correlate the radiance of the source and the signal measured by each instrument. We used the Hapke model to obtain the Mercury reflectance, and we included it in the radiometric model applied to the STC, HRIC and VIHI channels. The radiometric model here presented is a useful tool to predict the instruments performance: it permits to calculate the expected optical response of the instrument (the position in latitude and longitude of the filter footprints, the on-ground px dimensions, the on-ground speed, the smearing and the illumination angles of the observed points), and the detector behavior (the expected signal and the integration time to reach a specific SNR). In this work we derive the input flux and the integration times for the three channels of SIMBIO-SYS, using the radiometric model to obtain the source radiance for each Mercury surface area observed.
JANUS is the camera of the ESA mission JUICE, dedicated to high-resolution imaging in the extended-visible wavelength region (340 – 1080nm). The camera will observe Jupiter and its satellites providing detailed maps of their surfaces and atmospheres. During the mission, the camera will face a huge variety of observing scenarios ranging from the imaging of the surfaces of the satellites under varying illumination conditions to limb observation of the atmospheres. The stray-light performance of JANUS has been studied through non-sequential ray-tracing simulations with the aim to characterize and optimize the design. The simulations include scattering effects produced by micro-roughness and particulate contamination of the optical surfaces, the diffusion from mechanical surfaces and ghost reflections from refractive elements. The results have been used to derive the expected stray-light performance of the instrument and to validate the instrument design.
JANUS (Jovis Amorum Ac Natorum Undique Scrutator) is a high-resolution visible camera designed for the ESA space
mission JUICE (Jupiter Icy moons Explorer). The main scientific goal of JANUS is to observe the surface of the Jupiter
satellites Ganymede and Europa in order to characterize their physical and geological properties. During the design phases,
we have proposed two possible optical configurations: a Three Mirror Anastigmat (TMA) and a Ritchey-Chrétien (RC)
both matching the performance requirements. Here we describe the two optical solutions and compare their performance
both in terms of achieved optical quality, sensitivity to misalignment and stray light performances.
The JUICE (JUpiter ICy moons Explorer) satellite of the European Space Agency (ESA) is dedicated to the detailed study of Jupiter and its moons. Among the whole instrument suite, JANUS (Jovis, Amorum ac Natorum Undique Scrutator) is the camera system of JUICE designed for imaging at visible wavelengths. It will conduct an in-depth study of Ganymede, Callisto and Europa, and explore most of the Jovian system and Jupiter itself, performing, in the case of Ganymede, a global mapping of the satellite with a resolution of 400 m/px. The optical design chosen to meet the scientific goals of JANUS is a three mirror anastigmatic system in an off-axis configuration. To ensure that the achieved contrast is high enough to observe the features on the surface of the satellites, we also performed a preliminary stray light analysis of the telescope. We provide here a short description of the optical design and we present the procedure adopted to evaluate the stray-light expected during the mapping phase of the surface of Ganymede. We also use the results obtained from the first run of simulations to optimize the baffle design.
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.
JANUS (Jovis, Amorum ac Natorum Undique Scrutator) is the visible camera selected for the ESA JUICE mission to the Jupiter system. Resources constraints, S/C characteristics, mission design, environment and the great variability of observing conditions for several targets put stringent constraints on instrument architecture. In addition to the usual requirements for a planetary mission, the problem of mass and power consumption is particularly stringent due to the long-lasting cruising and operations at large distance from the Sun. JANUS design shall cope with a wide range of targets, from Jupiter atmosphere, to solid satellite surfaces, exosphere, rings, and lightning, all to be observed in several color and narrow-band filters. All targets shall be tracked during the mission and in some specific cases the DTM will be derived from stereo imaging. Mission design allows a quite long time range for observations in Jupiter system, with orbits around Jupiter and multiple fly-bys of satellites for 2.5 years, followed by about 6 months in orbit around Ganymede, at surface distances variable from 104 to few hundreds km. Our concept was based on a single optical channel, which was fine-tuned to cover all scientific objectives based on low to high-resolution imaging. A catoptric telescope with excellent optical quality is coupled with a rectangular detector, avoiding any scanning mechanism. In this paper the present JANUS design and its foreseen scientific capabilities are discussed.
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