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First results of the ESA/Mars Express orbiter around Mars

1er février 2004 First results of the ESA/Mars Express orbiter around Mars

The Mars Express spacecraft became on 2003 December 25th the first European satellite in orbit around Mars, joining the two NASA probes Mars Global Surveyor and Mars Odyssey. When the Mars Express orbit is still being adjusted, decreasing from a 12 hours period down to 7.5 jours, the on board instrumentation is tested before the full operational period after April. Then, the orbiter will work during at least one Martian year (687 days). Paris Observatory strongly contributed to the OMEGA instrument, which gave the first direct detection of water ice at the surface of Mars.

Paris Observatory is involved in two instruments of the payload :

OMEGA (Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité) is the infrared imaging spectrometer of Mars Express, built under the responsibility of the Institut d’Astrophysique Spatiale in Orsay (Principal Investigator : Jean-Pierre Bibring). LESIA strongly contributed to the definition and manufacturing of the infrared channel, with optical module and detector block built in Meudon. Other collaborations in the manufacturing of the instrument include IFSI (Italy) and IKI (Russia). The instrument works from the visible (channel from 0.36 to 1.08 microns) to near infrared (0.92-5.09 microns).and gives access to reconstructed spectral maps of Mars, or images at the 352 wavelengths dispersed by the spectrometer. This instrument is devoted to mineralogy studies, ice composition, atmospheric composition and dust analysis The orbit of Mars Express is almost polar (86dg inclination) and permits high resolution cartography of the surface of Mars at pericenter, about 250 km above the surface, following narrow strips which will be gathered to reconstitute orbit after orbit, global mineralogical maps of Mars PFS (Planetary Fourier Spectrometer) is a Fourier Transform Spectrometer, working in two channels from 1.25 to 4.5 microns and 6 to 45 microns, with a resolution of 1000 at 5 microns. It is principally devoted to the surface and atmospheric study of Mars, in particular for the detection of minor constituents, the retrieval of temperature profiles, and measures of surface temperatures.

OMEGA (Observatoire pour la Minéralogie, l’Eau, les Glaces et l’Activité) is the infrared imaging spectrometer of Mars Express, built under the responsibility of the Institut d’Astrophysique Spatiale in Orsay (Principal Investigator : Jean-Pierre Bibring). LESIA strongly contributed to the definition and manufacturing of the infrared channel, with optical module and detector block built in Meudon. Other collaborations in the manufacturing of the instrument include IFSI (Italy) and IKI (Russia). The instrument works from the visible (channel from 0.36 to 1.08 microns) to near infrared (0.92-5.09 microns).and gives access to reconstructed spectral maps of Mars, or images at the 352 wavelengths dispersed by the spectrometer. This instrument is devoted to mineralogy studies, ice composition, atmospheric composition and dust analysis The orbit of Mars Express is almost polar (86dg inclination) and permits high resolution cartography of the surface of Mars at pericenter, about 250 km above the surface, following narrow strips which will be gathered to reconstitute orbit after orbit, global mineralogical maps of MarsPFS (Planetary Fourier Spectrometer) is a Fourier Transform Spectrometer, working in two channels from 1.25 to 4.5 microns and 6 to 45 microns, with a resolution of 1000 at 5 microns. It is principally devoted to the surface and atmospheric study of Mars, in particular for the detection of minor constituents, the retrieval of temperature profiles, and measures of surface temperatures. The other instruments, for which Paris Observatory is not directly involved are : The camera HRSC (Deutsches Zentrum für Luft und Raumfahrt, Berlin), the spectrometer SPICAM (Institut Pierre Simon Laplace, Verrières le Buisson), the plasma instrument ASPERA (Swdeish Institute for Space Physics, Kiruna, Sweden), MARSIS) The subsurface radar (Rome University), which will be deployed in April, and finally the radio science experiment (Köln Univ.). Beagle II, the small descent probe which was due to make direct measurements on the Martian soil under the responsibility of Open University (United Kingdon), has unfortunately failed. The success of the orbit insertion of Mars Express is nevertheless a great success in the history of the European Space Agency. The fisrt results from Mars Express arrive until January 8th. They will be presented for the first time in Europe at the European Geophysical Union meeting in Nice (April 25-30). It is of course too early to give here complete results, but the first orbits of Mars Express confirmed that all the payload instruments are working, and first remarkable results are available, with the direct detection by OMEGA of the spectral signature of water ice and carbon dioxide ice in the South polar cap. PFS has detect carbon monoxide in its first spectra, and will give access to spatial repartition of this constituent. On the figure above, an image by OMEGA of Olympus Mons is given. This volcano is more than 20 km high. The width of the volcano is larger than the width of the observed band by OMEGA, and only a part of the caldera is observed. Comparison between summit and low altitude spectra show differences in atmospheric absorption, mainly due to carbon dioxide. The study of the variations of the atmospheric pressure, of the minor constituents and of the dust opacity will be made in Paris Observatory, when mineralogical studies will be made in IAS (Orsay), in collaboration with the many French and foreign laboratories participating to the mission.

These studies are realized with help of CNES, INSU and Paris Observatory for French part.Researchers from Paris Observatory involved:Links :

Contact

  • Pierre Drossart (Observatoire de Paris, LESIA)
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