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1.
Francois BeckerBernard SeguinThierry PhulpinJean Pierre Durpaire 《Acta Astronautica》1996,39(9-12):883-897
The estimation of land surface fluxes has been recognized in the last ten years as a major scientific issue for the improvement of our knowledge on heat and water budgets and therefore of models in meteorology, hydrology, agriculture and environment. Remote sensing is an adequate mean for filling the gap which exists between small scale instruments or modeling (10m) and the regional or global scales where they have to be determined with a typical grid element of the order of 1 to 10 km. IRSUTE (for Infra Red miniSatellite Unit for Terrestrial Environment) is a scientific small satellite mission providing thermal imagery for the determination and analysis of soil/vegetation/atmosphere processes at the field scale and therefore for providing the necessary data for a scaling-up of these processes from local to regional scales. The main specifications, will allow this instrument to optimize the correction of the sensed radiance and to retrieve the fluxes with an accuracy of the order of 50w/m2 (or 0.8mm/day). IRSUTE is designed to have high spatial resolution (50m), across and along track viewing capabilities, 5 channels : visible/NIR, 3.7 μ, and 3 TIR in the 8–11 μm band with a good radiometric sensitivity (NEΔT = 0.1 K). The instrument is to be implemented onboard a small satellite (typically a PROTEUS platform) placed on a sun-synchronous orbit allowing high repetitivity (1 to 3 days). It is based on the push-broom technique which uses IR-CCD linear array detectors positioned in the cryocooled focal plane of a large bandwidth collecting optics. 相似文献
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Israel G. Cabane M. Brun J-F. Niemann H. Way S. Riedler W. Steller M. Raulin F. Coscia D. 《Space Science Reviews》2002,104(1-4):433-468
ACP's main objective is the chemical analysis of the aerosols in Titan's atmosphere. For this purpose, it will sample the
aerosols during descent and prepare the collected matter (by evaporation, pyrolysis and gas products transfer) for analysis
by the Huygens Gas Chromatograph Mass Spectrometer (GCMS). A sampling system is required for sampling the aerosols in the
135'32 km and 22'17 km altitude regions of Titan's atmosphere. A pump unit is used to force the gas flow through a filter.
In its sampling position, the filter front face extends a few mm beyond the inlet tube. The oven is a pyrolysis furnace where
a heating element can heat the filter and hence the sampled aerosols to 250 °C or 600 °C. The oven contains the filter, which
has a thimble-like shape (height 28 mm). For transferring effluent gas and pyrolysis products to GCMS, the carrier gas is
a labeled nitrogen 15N2, to avoid unwanted secondary reactions with Titan's atmospheric nitrogen.
Aeraulic tests under cold temperature conditions were conducted by using a cold gas test system developed by ONERA. The objective
of the test was to demonstrate the functional ability of the instrument during the descent of the probe and to understand
its thermal behavior, that is to test the performance of all its components, pump unit and mechanisms.
In order to validate ACP's scientific performance, pyrolysis tests were conducted at LISA on solid phase material synthesized
from experimental simulation. The chromatogram obtained by GCMS analysis shows many organic compounds. Some GC peaks appear
clearly from the total mass spectra, with specific ions well identified thanks to the very high sensitivity of the mass spectrometer.
The program selected for calibrating the flight model is directly linked to the GCMS calibration plan. In order not to pollute
the two flight models with products of solid samples such as tholins, we excluded any direct pyrolysis tests through the ACP
oven during the first phase of the calibration. Post probe descent simulation of flight results are planned, using the much
representative GCMS and ACP spare models.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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Stepan Tulyakov Anton Ivanov Nicolas Thomas Victoria Roloff Antoine Pommerol Gabriele Cremonese Thomas Weigel Francois Fleuret 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(1):487-496
There are many geometric calibration methods for “standard” cameras. These methods, however, cannot be used for the calibration of telescopes with large focal lengths and complex off-axis optics. Moreover, specialized calibration methods for the telescopes are scarce in literature. We describe the calibration method that we developed for the Colour and Stereo Surface Imaging System (CaSSIS) telescope, on board of the ExoMars Trace Gas Orbiter (TGO). Although our method is described in the context of CaSSIS, with camera-specific experiments, it is general and can be applied to other telescopes. We further encourage re-use of the proposed method by making our calibration code and data available on-line. 相似文献
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F Raulin P Coll N Smith Y Benilan P Bruston M C Gazeau 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1999,24(4):453-460
Titan, the largest satellite of Saturn, with a dense atmosphere very rich in organics, and many couplings in the various parts of its "geofluid", is a reference for studying prebiotic chemistry on a planetary scale. New data have been obtained from experiments simulating this organic chemistry (gas and aerosol phases), within the right ranges of temperature and a careful avoiding of any chemical contamination. They show a very good agreement with the observational data, demonstrating for the first time the formation of all the organic species already detected in Titan atmosphere including, at last, C4N2, together with many other species not yet detected in Titan. This strongly suggests the presence of more complex organics in Titan's atmosphere and surface, including high molecular weight polyynes and cyanopolyynes. The NASA-ESA Cassini-Huygens mission has been successfully launched in October 1997. The Cassini spacecraft will reach the Saturn system in 2004 and become an orbiter around Saturn, while the Huygens probe will penetrate into Titan's atmosphere. In situ measurements, in particular from Huygens GC-MS and ACP instruments, will provide a detailed analysis of the organics present in the air, aerosols, and surface. This very ambitious mission should yield much information of crucial importance for our knowledge of the complexity of Titan's chemistry, and, more generally for the field of exobiology. 相似文献
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Exobiology is not only the study of the origin, distribution and evolution of life in the universe, but also of structures
— including at the molecular level, and processes — including organic chemical transformations — related to life. In that
respect, with its dense nitrogen atmosphere, which includes a noticeable fraction of methane, and the many organic compounds
which are present in the gas and aerosols phases, Titan appears to be a planetary object of prime interest for exobiology
in the Solar system, allowing the study of chemical organic evolution in a planetary environment over a long time scale. We
describe here some aspects of this extraterrestrial organic chemistry which involves many physical and chemical couplings
in the different parts of what can be called ‘Titan's geofluid’ (gas phase, aerosol phases and surface solid and maybe liquid
phases). The three complementary approaches which can be followed to study such chemistry of exobiological interest are considered.
Those are experimental simulations in the laboratory, chemical and photochemical modeling and of course observation, using
both remote sensing and in situ measurements, which is an essential approach. The Cassini-Huygens mission, that offers a unique
opportunity to study in detail the many aspects of Titan's organic chemistry, is discussed and the many expected exobiological
returns from the different instruments of the Cassini orbiter and the Huygens probe are considered.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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L.M. Mukhin D.F. Nenarokov N.V. Porschnev V.B. Bondarev B.G. Gelman G. Israel F. Raulin J. Runavot R. Thomas 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1987,7(12):329-335
SIGMA - 3 gas chromatograph on board VEGA 1 and 2 landing probes has been operated successfully in the 60 - 50 km altitude range, providing several in - situ chemical analysis of the gas and the aerosols of Venus cloud layers. Post flight calibration required to derive atmospheric abundancies from gas chromatograms were carried out using the SIGMA - 3 spare model. A Venus atmospheric aerosol simulation chamber was used in which sulfuric acid droplets were generated. Preliminary results of these calibration experiments indicate that the concentration of sulfuric acid in the upper part of the clouds ( 60 to 55 km) is about 1 mg/m3 and suggest that an additional constituant must be present in noticeable amount in the aerosols. From these experiments the mixing ratio upper limits of SO2 is 100 ppmV and of H2S and COS is few 10 ppmV. 相似文献
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S I Ramirez R Navarro-Gonzalez P Coll F Raulin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,27(2):261-270
A quantitative comparison of the products arising from the irradiation of a Titan's simulated atmosphere is presented. The energy sources used represent some of the main events that occur in the satellite's atmosphere. All of the compounds identified are classified in the hydrocarbon and nitrile chemical families. Almost all of the detected compounds in Titan's atmosphere are produced by one or more energy sources. The compounds with the highest energy yields include the C2 hydrocarbons, methanonitrile and ethanonitrile. The possibility of using some of the produced organics as tracer compounds during the Huygens descend to identify the leading energy form in the different atmospheric levels remains open. 相似文献
10.
Franois Raulin Alain Bossard 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1984,4(12):75-82
Atmospheric chemistry may be one of the important pathways to the synthesis of organic compounds in a planetary periphery. Depending on the nature of the carbon source (CH4, CO or CO2), the main composition of the atmosphere, and the respective roles of the various energy sources, is it possible, and to what extent, to produce organics? What kind of gaseous mixture is the most favourable to prebiotic organic syntheses? How far can the results of laboratory works be extrapolated to the case of planetary atmospheres? These questions are discussed, on the basis of several available laboratory data, and by considering the main atmospheric composition of the planets of the solar system, and the list of organic compounds which have already been dettected in their atmospheres. 相似文献