This article presents the MISTIGRI project of a microsatellite developed by the French space agency Centre National d'Etudes Spatiales (CNES) in cooperation with Spain (Image Processing Laboratory of the University of Valencia and Centro para el Desarrollo Tecnológico Industrial (CDTI)). MISTIGRI is a mission that has the originality of combining a high spatial resolution (∼50 m) with a daily revisit in the thermal infrared (TIR). MISTIGRI is an experimental mission devoted to demonstrate the potential of such TIR data for future operational missions. The scientific goals and expected applications of the mission are described: they encompass the monitoring of (i) agricultural areas and related hydrological processes, (ii) urban areas, and (iii) coastal areas and continental waters. Then, the specifications on spatial resolution, revisit frequency, overpass time, and spectral configuration are justified. The strategy of the mission is based on the combination with a network of long-term experimental sites. It will also make possible observing some areas facing rapid climatic change. The choice of the orbit is presented. Finally, we give rapid overviews of both the instrumental concept and the proposed mission architecture.
Purpose: Interference of dose application in scanned beam particle therapy and organ motion may lead to interplay effects with distorted dose to target volumes. Interplay effects depend on the speed and direction of the scanning beam, leading to fringed field edges (scanning parallel to organ motion direction) or over‐ and under‐dosed regions (both directions are orthogonal). Current repainting methods can mitigate interplay effects, but are susceptible to artefacts when only a limited number of repaints are applied. In this study a random layered‐repainting strategy was investigated. Methods: Mono‐energetic proton beams were irradiated to a 10 ×10 cm2 scanned field at a Varian ProBeam facility. Applied dose was measured with a 2D amorphous silicon detector mounted on a motion platform (CIRS dynamic platform). Motion was considered with different cycles, directions and translations up to ±8 mm. Dose distributions were measured for a static case, regular repainting (repeated meander‐like path) and random repainting. Latter was realized by randomly distributing single spot locations during irradiation for a given number of repaints. Efficiency of repainting was analyzed by comparison to the static case. A simulation tool based on treatment logs and motion information was developed to compare measurement results to expected dose distributions. Results: Regular repainting could reduce motion artefacts, but dose distortion was strongly dependent on motion direction. Random repainting with same number of repaints (N=4) showed superior results, independent of target movement direction, while introducing slight penalty on delivery times, caused by an increase of overall scanning travel distance. The simulation tool showed good agreement to measured results. Conclusion: The results demonstrate significant improvement in terms of dose conformity when layered repainting is applied in a randomized fashion. This allows for reduced target margins during treatment planning and limited number of repaints. A combination with e.g. respiratory gating is straight‐forward. Authors are employees of Varian Medical Systems Particle Therapy GmbH
PARASOL, second satellite of the CNES micro satellite product line MYRIADE has been successfully launched from KOUROU in December 2004. The PARASOL mission purpose is to perform measurements of the polarized and multi-directional reflectances, on ground areas previously observed by the CALIPSO LIDAR. The Laboratoire d'Optique Atmosphérique (LOA-CNRS) in the northern French city of Lille is the PARASOL scientific Principal Investigator.PARASOL is now flying in the so called A-Train constellation with AQUA and AURA. The constellation will be soon completed with CALIPSO and CLOUDSAT. This spacecraft set will be an exceptional space observatory which will supply an exhaustive data bank dedicated to the climatology forecasts.The PARASOL satellite has been developed by CNES, also in charge of the control center development, the telemetry and telecommand earth terminals, some part of the ground mission center, the image performance expertise and all the in flight operations.The hereafter paper will present the PARASOL mission and the main characteristics of the satellite, the launch and the ascent phase in coordination with the A-TRAIN. Then it will describe the PARASOL ground segment. The last part will present the first performances analysis.Downloaded by CARLETON UNIVERSITY LIBRARY on July 30, 2015 | http://arc.aiaa.org |
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