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.
Mezzocielo is a proposed innovative type of telescope, conceived for achieving simultaneous observations of the available sky using a single monocentric collecting optical unit and leaving to an array of optical correctors the purpose of detecting the final starlight. Thanks to a spherical array of field lenses, encompassing an optical fluid and illuminating the correctors, the telescope allows to realize a whole-sky surveying (the estimated Field of View is more than 10 thousand square degrees), with the aim of detect and observe space debris, even if other possibilities are available (the observatory could be configured for different astronomical purposes, like ecliptic observations, extragalactic monitoring or Milky Way monitoring). Objective of the present work is demonstrating the actual feasibility of this instrument and, at the same time, developing a model employable for its first sizing, namely for the selection of the most appropriate dimensions of the whole telescope and its most stressed component, according to the mechanical and hydraulic loads, the boundary conditions and few other constraints. The analytical procedure was eventually verified through a Finite Element Analysis of the most loaded field lens, which has demonstrated the reliability of our approach in terms of safety.
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.
Rosetta is one of the cornerstone missions of the European Space Agency for having a rendezvous with the comet 67P/Churyumov-Gerasimenko in 2014. The imaging instrument on board the satellite is OSIRIS (Optical, Spectroscopic and Infrared Remote Imaging System), a cooperation among several European institutes, which consists of two cameras: a Narrow (NAC) and a Wide Angle Camera (WAC).
The WAC optical design is an innovative one: it adopts an all reflecting, unvignetted and unobstructed two mirror configuration which allows to cover a 12° × 12° field of view with an F/5.6 aperture and gives a nominal contrast ratio of about 10–4.
The flight model of this camera has been successfully integrated and tested in our laboratories, and finally has been integrated on the satellite which is now waiting to be launched in February 2004.
In this paper we are going to describe the optical characteristics of the camera, and to summarize the results so far obtained with the preliminary calibration data. The analysis of the optical performance of this model shows a good agreement between theoretical performance and experimental results.
In this paper the design of a novel catadioptric optical solution for the Stereo Channel (STC) of the imaging system SIMBIOSYS for the BepiColombo ESA mission to Mercury is presented.
The main scientific objective is the 3D global mapping of the entire surface of Mercury with a scale factor of 50 m per pixel at periherm in five different spectral bands.
The system consists of two sub-channels looking at ±20° from nadir. They share the detector and all the optical components with the exception of the first element, a rhomboid prism. The field of view of each channel is 5.3° × 4.5° and the scale factor is 23 arcsec/pixel. The system guarantees an aberration balancing over all the field of view and wavelength range with optimal optical performance.
For stray-light suppression, an efficient baffling system able to well decouple the optical paths of the two subchannels has been designed.
The paper describes the optical design and performance budget of a novel catadioptric instrument chosen as baseline for the Stereo Channel (STC) of the imaging system SIMBIOSYS for the BepiColombo ESA mission to Mercury.
The main scientific objective is the 3D global mapping of the entire surface of Mercury with a scale factor of 50 m per pixel at periherm in four different spectral bands.
The system consists of two twin cameras looking at ±20° from nadir and sharing some components, such as the relay element in front of the detector and the detector itself. The field of view of each channel is 4° x 4° with a scale factor of 23’’/pixel. The system guarantees good optical performance with Ensquared Energy of the order of 80% in one pixel.
For the straylight suppression, an intermediate field stop is foreseen, which gives the possibility to design an efficient baffling system.
Optical instruments for space missions work in hostile environment, it’s thus necessary to accurately study the effects of ambient parameters variations on the equipment.
In particular optical instruments are very sensitive to ambient conditions, especially temperature. This variable can cause dilatations and misalignments of the optical elements, and can also lead to rise of dangerous stresses in the optics. Their displacements and the deformations degrade the quality of the sampled images.
In this work a method for studying the effects of the temperature variations on the performance of imaging instrument is presented. The optics and their mountings are modeled and processed by a thermo-mechanical Finite Element Model (FEM) analysis, then the output data, which describe the deformations of the optical element surfaces, are elaborated using an ad hoc MATLAB routine: a non-linear least square optimization algorithm is adopted to determine the surface equations (plane, spherical, nth polynomial) which best fit the data. The obtained mathematical surface representations are then directly imported into ZEMAX for sequential raytracing analysis. The results are the variations of the Spot Diagrams, of the MTF curves and of the Diffraction Ensquared Energy due to simulated thermal loads.
This method has been successfully applied to the Stereo Camera for the BepiColombo mission reproducing expected operative conditions.
The results help to design and compare different optical housing systems for a feasible solution and show that it is preferable to use kinematic constraints on prisms and lenses to minimize the variation of the optical performance of the Stereo Camera.
P. Schipani, L. Marty, M. Mannetta, F. Esposito, C. Molfese, A. Aboudan, V. Apestigue-Palacio, I. Arruego-Rodríguez, C. Bettanini, G. Colombatti, S. Debei, M. Genzer, A.-M. Harri, E. Marchetti, F. Montmessin, R. Mugnuolo, S. Pirrotta, C. Wilson
KEYWORDS: Mars, Data archive systems, Planetary science, Sensors, Calibration, Data conversion, Data processing, Data acquisition, Atmospheric sensing, Planets
DREAMS (Dust Characterisation, Risk Assessment, and Environment Analyser on the Martian Surface) is a payload
accommodated on the Schiaparelli Entry and Descent Module (EDM) of ExoMars 2016, the ESA – Roscosmos mission
to Mars successfully launched on 14 March 2016. The DREAMS data will be archived and distributed to the scientific
community through the ESA’s Planetary Science Archive (PSA). All data shall be compliant with NASA’s Planetary
Data System (PDS4) standards for formatting and labelling files. This paper summarizes the format and content of the
DREAMS data products and associated metadata. The pipeline to convert the raw telemetries to the final products for the
archive is sketched as well.
KEYWORDS: Data storage, Near infrared, Computing systems, Data processing, Sensors, Data archive systems, Data modeling, Control systems, Databases, Data conversion
The NISP instrument on board the Euclid ESA mission will be developed and tested at different levels of integration
using various test equipment which shall be designed and procured through a collaborative and coordinated effort. The
NISP Instrument Workstation (NI-IWS) will be part of the EGSE configuration that will support the NISP AIV/AIT
activities from the NISP Warm Electronics level up to the launch of Euclid. One workstation is required for the NISP
EQM/AVM, and a second one for the NISP FM. Each workstation will follow the respective NISP model after delivery
to ESA for Payload and Satellite AIV/AIT and launch. At these levels the NI-IWS shall be configured as part of the
Payload EGSE, the System EGSE, and the Launch EGSE, respectively. After launch, the NI-IWS will be also re-used in
the Euclid Ground Segment in order to support the Commissioning and Performance Verification (CPV) phase, and for
troubleshooting purposes during the operational phase.
The NI-IWS is mainly aimed at the local storage in a suitable format of the NISP instrument data and metadata, at local
retrieval, processing and display of the stored data for on-line instrument assessment, and at the remote retrieval of the
stored data for off-line analysis on other computers.
We describe the design of the IWS software that will create a suitable interface to the external systems in each of the
various configurations envisaged at the different levels, and provide the capabilities required to monitor and verify the
instrument functionalities and performance throughout all phases of the NISP lifetime.
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.
KEYWORDS: Space telescopes, Space operations, Telescopes, Space operations, Local area networks, Databases, Control systems, Fermium, Frequency modulation, Device simulation, Data modeling
The Near Infrared Spectro-Photometer (NISP) on board the Euclid ESA mission will be developed and tested at various
levels of integration by using various test equipment. The Electrical Ground Support Equipment (EGSE) shall be
required to support the assembly, integration, verification and testing (AIV/AIT) and calibration activities at instrument
level before delivery to ESA, and at satellite level, when the NISP instrument is mounted on the spacecraft. In the case of
the Euclid mission this EGSE will be provided by ESA to NISP team, in the HW/SW framework called "CCS Lite", with
a possible first usage already during the Warm Electronics (WE) AIV/AIT activities. In this paper we discuss how we
will customize that "CCS Lite" as required to support both the WE and Instrument test activities. This customization will
primarily involve building the NISP Mission Information Base (the CCS MIB tables) by gathering the relevant data from
the instrument sub-units and validating these inputs through specific tools. Secondarily, it will imply developing a
suitable set of test sequences, by using uTOPE (an extension to the TCL scripting language, included in the CCS
framework), in order to implement the foreseen test procedures. In addition and in parallel, custom interfaces shall be set
up between the CCS and the NI-IWS (the NISP Instrument Workstation, which will be in use at any level starting from
the WE activities), and also between the CCS and the TCC (the Telescope Control and command Computer, to be only
and specifically used during the instrument level tests).
KEYWORDS: Control systems, Software development, Space operations, Data processing, Sensors, Control systems, Data acquisition, Field programmable gate arrays, Technetium, Electronics, Calibration
In this paper we describe the detailed design of the application software (ASW) of the instrument control unit (ICU) of
NISP, the Near-Infrared Spectro-Photometer of the Euclid mission. This software is based on a real-time operating
system (RTEMS) and will interface with all the subunits of NISP, as well as the command and data management unit
(CDMU) of the spacecraft for telecommand and housekeeping management. We briefly review the main requirements
driving the design and the architecture of the software that is approaching the Critical Design Review level. The
interaction with the data processing unit (DPU), which is the intelligent subunit controlling the detector system, is
described in detail, as well as the concept for the implementation of the failure detection, isolation and recovery (FDIR)
algorithms. The first version of the software is under development on a Breadboard model produced by
AIRBUS/CRISA. We describe the results of the tests and the main performances and budgets.
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.
The JANUS (Jovis, Amorum ac Natorum Undique Scrutator) will be the on board camera of the ESA JUICE satellite dedicated to the study of Jupiter and its moons, in particular Ganymede and Europa. This optical channel will provide surface maps with plate scale of 15 microrad/pixel with both narrow and broad band filters in the spectral range between 0.35 and 1.05 micrometers over a Field of View 1.72 × 1.29 degrees2. The current optical design is based on TMA design, with on-axis pupil and off-axis field of view. The optical stop is located at the secondary mirror providing an effective collecting area of 7854 mm2 (100 mm entrance pupil diameter) and allowing a simple internal baffling for first order straylight rejection. The nominal optical performances are almost limited by the diffraction and assure a nominal MTF better than 63% all over the whole Field of View. We describe here the optical design of the camera adopted as baseline together with the trade-off that has led us to this solution.
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.
C. Molfese, P. Schipani, L. Marty, F. Esposito, S. D'Orsi, M. Mannetta, S. Debei, C. Bettanini, A. Aboudan, G. Colombatti, R. Mugnuolo, E. Marchetti, S. Pirrotta
KEYWORDS: Space operations, Environmental sensing, Sensors, Power supplies, Aerospace engineering, Temperature metrology, Humidity, Data acquisition, Mars, Near infrared
This paper describes the Electrical Ground Support Equipment (EGSE) of the Dust characterization, Risk assessment, and Environment Analyser on the Martian Surface (DREAMS) scientific instrument, an autonomous surface payload package to be accommodated on the Entry, Descendent and landing Module (EDM) of the ExoMars 2016 European Space Agency (ESA) mission. DREAMS will perform several kinds of measurements, such as the solar irradiance with different optical detectors in the UVA band (315-400nm), NIR band (700-1100nm) and in "total luminosity" (200 –1100 nm). It will also measure environmental parameters such as the intensity of the electric field, temperature, pressure, humidity, speed and direction of the wind. The EGSE is built to control the instrument and manage the data acquisition before the integration of DREAMS within the Entry, Descendent and landing Module (EDM) and then to retrieve data from the EDM Central Checkout System (CCS), after the integration. Finally it will support also the data management during mission operations. The EGSE is based on commercial off-the-shelf components and runs custom software. It provides power supply and simulates the spacecraft, allowing the exchange of commands and telemetry according to the protocol defined by the spacecraft prime contractor. This paper describes the architecture of the system, as well as its functionalities to test the DREAMS instrument during all development activities before the ExoMars 2016 launch.
In this paper the results of the thermo-elastic analysis performed on the Stereo Imaging Channel of the imaging system SIMBIO-SYS for the BepiColombo ESA mission to Mercury is presented. The aim of the work is to determine the expected stereo reconstruction accuracy of the surface of the planet Mercury, i.e. the target of BepiColombo mission, due to the effects of the optics misalignments and deformations induced by temperature changes during the mission lifetime. The camera optics and their mountings are modeled and processed by a thermo-mechanical Finite Element Model (FEM)
program, which reproduces the expected optics and structure thermo-elastic variations in the instrument foreseen operative temperature range, i.e. between -20 °C and 30 °C. The FEM outputs are elaborated using a MATLAB optimization routine: a non-linear least square algorithm is adopted to determine the surface equation (plane, spherical, nth polynomial) which best fits the deformed optical surfaces. The obtained surfaces are then directly imported into ZEMAX raytracing code for sequential raytrace analysis.
Variations of the optical center position, boresight direction, focal length and distortion are then computed together with
the corresponding image shift on the detector.
The overall analysis shows the preferable use of kinematic constraints, instead of glue classical solution, for optical
element mountings, this minimize the uncertainty on the Mercury Digital Terrain Model (DTM) reconstructed via a stereo-vision algorithm based on the triangulation from two optical channels.
Optical instruments for space missions work in hostile environment, it's thus necessary to accurately study the effects of
ambient parameters variations on the equipment performance.
In particular, optical instruments are very sensitive to ambient conditions, especially temperature. This variable can
cause dilatation and misalignment of the optical elements, and can also lead to rise of dangerous stresses in the optics.
Optical elements displacements and surface deformations degrade the quality of the sampled images.
In this work a method for simulating and studying the effects of the thermal deformations, particularly the impact on the
expected optical performance, is presented.
Optical elements and their mountings are modelled and processed by a thermo-mechanical Finite Element Model (FEM)
analysis, reproducing expected operative conditions. The FEM output is elaborated into a MATLAB optimisation code; a
non-linear least square algorithm is used to determine the equation of the best fitting nth degree polynomial, or the
spherical surface of the deformed lenses and mirrors; model accuracy is 10-8 m.
The obtained mathematical surface representations are then directly imported into ZEMAX raytracing software for
sequential raytrace analysis. The results are spot diagrams, chief ray coordinates on the detector, MTF curves and
Diffraction Encircled Energy variations due to simulated thermal loads.
This analysis helps to design and compare different optical housing systems for finding a feasible mounting solution.
The described method has been applied successfully to the optics and mountings of a stereo-camera for the
BepiColombo mission. Different types of lenses and prisms constraints have been designed and analysed. The results
show the preferable use of kinematic constraints, instead of using glue, to correctly maintain the instrument focus in orbit
around Mercury considering an operative temperature range between -20°C and +30°C.
This paper deals with the optical design and preliminary optomechanical tolerances of HRIC, the High Resolution Imaging Channel of the SIMBIO-SYS instrument, selected as part of the scientific payload for the ESA cornerstone BepiColombo mission to Mercury. Under the lead of Italy (Principal Investigator: E. Flamini), the project is based on an international co-operation with Institutes from France and Switzerland. Starting from the stringent scientific requirement of 5m ground pixel scale at 400 km from the planet surface, a robust optical design based on a catadioptric Ritchey-Chretien configuration modified with a dedicated corrector camera has been achieved. The optimized configuration is convenient in terms of image quality, number of optical elements, and total length. The channel guarantees a corrected FoV of about 1.5° and allows the achievement of the required resolution with a detector of 2k × 2k pixels. The telescope is diffraction limited, thanks to its focal ratio (F/8), and shows an optimised radiometric flux within the operative spectral range (400 - 900 nm). The channel is equipped with one panchromatic and 3 selective filters. The operation plan foresees the coverage of at least 20% of the whole Hermean surface with the HRIC. The preliminary optomechanical tolerances and the corresponding image quality have been analyzed. Further thermo-mechanical analysis is in progress, which is being analyzed by means of ray-tracing tools for image quality evaluation.
The optical design of the STereoscopic imaging Channel (STC) of the imaging/spectroscopic system SIMBIOSYS for
the ESA BepiColombo mission is presented. The main aim of this system is the global stereo mapping of planet
Mercury surface during the BepiColombo mission lifetime.
The instrument consists of two identical cameras looking at ±20° from nadir which are sharing some optical
components and the detector. The instrument has a 23"/pixel scale factor, corresponding to 50 m/px at 400 km from the
surface, on a 4°x 4° FoV; imaging in four different spectral bands, between 540 nm and 890 nm, is foreseen. The STC
optical characteristics guarantee global stereo mapping of the whole Mercury surface with all the filters.
The coupling of an achromatic air-spaced doublet with a relay lens system allows good aberration balancing over
all the field of view: the diffraction Ensquared Energy inside one pixel of the detector is of the order of 80%. In
addition, an intermediate field stop gives the possibility of designing an efficient baffling system for straylight rejection.
To cope with the hazardous radiation environment in which the spacecraft will be immersed in during the mission,
all the glasses selected for the design are rad-hard type.
A preliminary tolerance analysis has also been undertaken showing a low criticality level for manufacturing,
alignment and stability of the system.
This paper describes the optical design criteria and expected image quality of the High Resolution Imaging Channel (HRIC), which is part of the Spectrometers and Imagers for Mercury Planetary Orbiter (MPO) BepiColombo Integrated Observatory SYStem (SIMBIO-SYS) suite, for imaging and spectroscopic investigation of Mercury. SIMBIO-SYS has been selected by ESA as part of the scientific payload of the ESA BepiColombo mission to Mercury. HRIC has the main objective of characterising Mercury surface features with a very high spatial resolution in the visible. The optical design has been optimised to achieve the stringent scientific requirement of 5 m ground pixel size at 400 km from the planet surface. The adopted catadioptric optical configuration provides a resolution of 2.5"/pixel for a pixel size of 10 micron. The focal ratio is F#8 in order to be diffraction limited at 400 nm and to optimise radiometric flux and overall mechanical dimensions. The optical design solution includes two hyperbolic mirrors optimized with a dioptric camera, in order to correct the field of view of 1.47°, covered by a detector of 2k x 2k pixels. The mixed (reflective + refractive) solution guarantees a good balance of achieved optical performances and optimisation of resources (mainly volume and mass). The adopted configuration corrects and transmits well over the whole band of observation (400 - 900 nm).
The WAC is a telescope developed by University of Padova for the OSIRIS experiment, mainly composed by two instruments, Narrow Angle Camera and Wide Angle Camera, and the related electronics. The payload will fly on board of the Rosetta ESA scientific mission, that will be flown to encounter Comet Wirtanen after about 10 years of flight in 2013. WAC main scientific objectives are to follow structure evolution in the coma and monitor their dynamics. To fulfill scientific requirements, the optical characteristics of the WAC telescope may be summarized as follows: wide field of view of 12° X 12°, focal length of 140 mm, operate in the wave-length range 240-1000nm after 10 years in space, Encircled Energy greater than 70% over the entire FoV, contrast ratio of 10-4 to detect coma activities against a bright nucleus, minimum exposure time of 10 msec with a repeatability better than 1/500, scattered light rejection for sources inside and outside FoV. This paper deals with the design optimization of critical parts and acceptance test campaign performed to validate the thermo-structural behavior of the WAC. The functional and performance tests carried out at experiment and system level demonstrated the overall capability of the telescope to satisfy the system and scientific requirements.
The scope of the present document is to describe the Front Door Mechanism of Wide Angle Camera and Narrow Angle Camera of the OSIRS payload and to demonstrate the safety of the mechanism itself. To match the scientific goals it has to prevent the contamination of the telescopes during ground and in -flight operations. Moreover for the in-flight calibration the door itself will be used for the flat field of the cameras. The original design has been carried out according to optimisation techniques and successfully tested during the qualification and acceptance campaign. The results obtained demonstrated that the mechanism is fully compliant to the interface specifications and its performances are not affected by the environmental stresses and by the overall life cycling.
A new concept of electromechanical shutter has been designed and qualified for the OSIRIS imaging system to fly onboard the Rosetta Mission, whose main scientific goal are the randez-vous and the study of the Comet Wirtanen. The shutter, is composed by two blades, driven by dedicated four-bar linkages, that are moved independently by two torque motors each mounted on the same shaft of an high resolution optical encoder. A dedicate fail safe mechanism is also integrated in order to make the shutter single point failure proof. The mechanism has been designed in order to fulfil high reliability with high performance. Reliability has been verified by life testing over 100000 cycles (factor 2 on expected operative cycles). Performance verified by calibration show that the minimum exposure time with a uniformity of 1/500 is 10 ms over a large sensitive area (about 30x30 mm). The exposure time can vary from 10ms to 5s. Scope of this paper is to present the mechanism and to demonstrate that it accomplishes the sciences and interfaces requirements.
Rosetta is the cornerstone mission of ESA devoted to the study of minor bodies of Solar System. The mission will be launched on January 2003 and has the rendez-vous with P/Wirtanen comet (on November 2011) as primary target. The final aim of the mission will be a better understanding of the formation and composition of early Solar System and of its evolution over the last 4.5 billion years. Rosetta has a complex instrumentation devoted both to remote sensing and to in situ investigation. The authors were involved in the design and manufacturing of the Wide Angle Camera (WAC) of the OSIRIS imaging system. The WAC has a very peculiar optical system based on two aspherical mirrors in an off axis configuration, and will be principally devoted to the study of the very faint gas and dust cometary features. To reach this goal an innovative baffling system was designed and constructed in order to reach the stray-light suppression requirements both for source inside and outside the field of view of the camera. In particular a contrast ratio of 10-4 inside the field of view is needed in order to detect gaseous and dusty features close to the nucleus of the comet. In this paper the process of baffling design and manufacturing is described: the behavior of the baffle, previously calculated by numerical simulations from the mechanical and optical points of view, was assessed both for the single elements and for the complete assembly as described in this paper.
KEYWORDS: Sensors, Transmission electron microscopy, Temperature metrology, Atmospheric sensing, Temperature sensors, Atmospheric modeling, Platinum, Resistance, Data acquisition, Thermal effects
First results about the performance of the temperature sensors (TEM) of Huygens Atmospheric Structure Instrument (HASI) obtained during Flight Model test campaign are presented and discussed. TEM belongs to the STUB subsystem of HASI, which is a multidisciplinary experiment package dedicated to the investigation of Titan atmosphere during the descent of the Huygens probe. TEM sensors are described, their characteristics and performances discussed and the data of thermal tests carried out at subsystem level and at probe level evaluated. From this preliminary analysis it seems that the sensors are suited to achieve the scientific objective of HASI experiment if post flight data correction is appropriately done.
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