The Mars Sample Return mission is a multiple probe mission to collect rock samples from Mars and bring them to Earth. The Perseverance rover is currently collecting samples on Mars. Tasked with the recovery of the Mars samples in Mars orbit and their return to Earth, the Earth Return Orbiter (ERO) is the last probe of the mission. In order to capture the Orbiting Sample (OS), which contains the Mars rock samples, the ERO will first detect the OS at long distance using its Narrow Angle Camera (NAC). Because the OS will be a faint object of magnitude 12, its detection is a challenge. One part of this challenge is to minimize the straylight caused by the illumination of the camera by much brighter out of field sources, such as the Sun and also the planet Mars. We describe here the design steps taken to minimize straylight, starting with measurement, design principles for the baffle and the objective, then finally simulations and their results.
Within the framework of the 3MI instrument for METOP-SG satellite, Sodern develops the Focal Plane Assemblies (FPAs) for the SWIR and VNIR detectors. The main functions of these FPAs are the thermal cooling, the dimensional stability of the detectors and the mechanical withstanding with respects to the thermal and mechanical environments. From a mechanical point of view, the mechanical requirements are identical for the two FPAs with notably stiffness above 500Hz. On the other hand, from a thermal point of view, the temperature environment and thermal control principle between SWIR and VNIR FPAs are different by the use of a heater for SWIR and a TEC for VNIR. At last, the SWIR FPA turns out to be the more challenging case with a high insulation, up to 200K/W, between cold parts (-90°C) and hot interface (25°C) and also a high coupling of 2.7K/W with the cold sink. This paper shows how a single architecture composed of a hexapod structure made of 6 titanium shafts and a thermal strap made of low diameter copper strands permits to achieve the best compromise between thermal and mechanical requirements for both FPAs. In addition to technical aspects, this common architecture also answers to the aim of cost cutting for the different phases of the project: design sharing, grouping of supplies, mutual qualification tests, shared integration tools and processes. Several models have been integrated and tested to verify the performances and the withstanding to thermal and mechanical environments.
DECLIC is a joint CNES/NASA research program to be implemented in the International Space Station (ISS). The facility is dedicated to the study of materials science under microgravity, and the processing operations will take place in an ISS EXPRESS rack from 2006 to 2008. Command and control will be performed from ground thanks to the possibility for scientists to monitor quasi real time images from their space experiment. Its modular design will make it able to accommodate a large variety of experiments. Cells containing the materials are placed together with their specific instrumentation (heaters, actuators, and scientific probes) in inserts that can easily be put in and removed from an experiment locker. The latter provides several illumination sources to the samples, that are used for interferometry or microscopy observations as well as optical transmission or light scattering measurements. These measurements are done in the other side of the locker by different sensors (cameras, photodiode). A second locker provides power, supplies temperature regulation or experiment control as well as data handling. This paper focuses on the optical measurements: it will describe the different sources and sensors available in the facility and give their performance based on models or measurements done on different types of experiments along the qualification process of the engineering model.
This paper, “Diagnostics optiques pour la mesure de fluides critiques en micro-gravité dans les instruments ALICE et DECLIC," was presented as part of International Conference on Space Optics—ICSO 1997, held in Toulouse, France.
DECLIC, a Facility dedicated to the study of transparent media under microgravity, will be used in an ISS EXPRESS Rack. This paper focuses on the EXL which contains two optical boxes disposed on two opposite sides of the cavity where the Inserts to be studied shall be locked. At the moment, three types of inserts are planned to be accommodated in the EXL. Various optical diagnostics are available by configuring the EXL (sources, sensors, mechanisms). After the presentation of the EXL design, this article deals with some manufacturing and testing aspects, such as the use of COTS (cameras). Specific OGSE have been developed in order to simulate the optical interfaces and the propagation of beams in the inserts. Three models of the EXL have been integrated and fully tested, including the Flight Model. The sequence of tests, the performances measured, and then some images of the experiments performed with the inserts will be presented.
As a manufacturer of optical systems for space applications, Sodern is faced with the necessity to design optical systems which image quality remains stable while the environment temperature changes. Two functions can be implemented: either a wavefront control or the athermalization of the optical system. In both cases, the mechanical deformations and thermal gradients are calculated by finite-element modeling with the IDEAS NX7 software. The data is then used in CODE V models for wavefront and image quality evaluation purposes. Two cases are presented: one is a UV beam expander in which a wavefront control is implemented and the other is an athermalized IR camera. The beam expander has a wavefront–tuning capability by thermal control. In order to perform the thermo-optical analysis in parallel with the opto-mechanical development, the thermo-optical modeling is done step by step in order to start before the mechanical design is completed. Each step then includes a new modeling stage leading to progressive improvements in accuracy. The IR camera athermalization is achieved through interaction between the mechanical CAD software and the optical design software to simulate the axial thermal gradients, radial gradients and all other thermal variations. The purpose of this paper is to present the steps that have led to the final STOP (Structural, Thermal Optical) analysis. Using incremental accuracy in modeling the thermo-optical effects enables to take them into account very early in the development process to devise all adjustment and test procedures to apply when assembling and testing the optical system.
ALICE is an instrument developed for optical analysis of fluids near their critical point in Manned Space Station. A first model is used since July 1992 in the MIR Station. Two optical subsystems contain light source, imagery and measurement tools. Between them, in a thermostat, two sample cell units are experimented. The six available diagnostics, in coherent and incoherent light, are presented with the most significant results.
A new instrument for Earth polarized observation is investigated. The POLDER system includes a telocentric wide field angle lens, a CCD matrix detector and, in between, a rotating wheel holding different spectral filters and polarizers assuming a registration function. Characteristics of the camera are presented.
The imaging instrument and main subassemblies, and the calibration device on board the Vegetation remote sensing mission are described. The possible error sources are examined and the final performances are compared with specifications. A brief description of operational use is given.
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