Repartition of H2O and CO2 ices on the south polar cap of Mars Observations OMEGA/Mars Express

1 March 2004

The observations of Mars Express around Mars began on 8 january, and a first publication, on which several astronomers from Paris Observatory are co-authors, is getting out in Nature about the observations by the imaging spectrometer OMEGA of polar ices on Mars. For the first time, OMEGA allows to determine directly the repartition of the two types of ices H2O and CO2.

The composition in carbon dioxide ice (CO2) or water ice (H2O) remained discussed until very recently. The observations by Mars Odyssey had shown, by indirect arguments, the presence of water ice in the southern polar cap (that was believed before made up exclusively of carbon dioxide ice). The measurements by OMEGA allow the first direct detections of the distribution of the two types of ice; the Martian season of southern hemisphere being the end of summer, this detection shows that these ices are present permanently. The abundance of water vapor in the atmosphere being very weak on Mars, the detection of permanent reservoirs of ice is a major element to understand the ice/atmosphere exchanges during Martian seasons.

Figure 1 Maps of the CO2 and H2O ices on the South Pole of Mars, produced by the infra-red imaging spectrometer OMEGA of Mars Express (data from January 18 to February 11, 2004). On the left, the signature in absorption of the carbonic ice is coded from blue (strong absorption) to chestnut (areas free of CO2 ice); on the right, the spectral signature of the water ice is coded in the same way from blue (strong absorption) to the red (without ice). The comparison of the two maps shows that the extension of the water ice is more important than that of the carbon dioxide ice, certain areas being made up of water ice only.

The OMEGA team: M. Berthé1, J-P. Bibring1, Y. Langevin1, S. Erard1, O. Forni1, A. Gendrin1, B. Gondet1, N. Manaud1, F. Poulet1, G. Poulleau1, A. Soufflot1, M. Combes2, P. Drossart2, T. Encrenaz2, T. Fouchet2, R. Melchiorri2, G. Bellucci3, F. Altieri3, V. Formisano3, G. Bonello3, S. Fonti3, F. Capaccioni3, P. Cerroni3, A. Coradini3, V. Kottsov4, N. Ignatiev4, V. Moroz4, D. Titov4, L. Zasova4, N. Mangold5, P. Pinet6, B. Schmitt7, C. Sotin8, E. Hauber9, H. Hoffmann9, R. Jaumann9, U. Keller10, R. Arvidson11, J. Mustard12, T. Duxbury13, F. Forget14
IAS, 91405, Orsay Campus, France, 2LESIA, Observatoire de Paris/Meudon, 92195 Meudon, 3IFSI-INAF, Rome, Italy, 4IKI, Moscow, Russia, Â 5OrsayTerre, Orsay Campus, 91405 France, 6Observatoire Midi-PyrÃ©nÃ©es, 31000 Toulouse, France, 7Laboratoire de PlanÃ©tologie, 38400 France, 8PlanÃ©tologie, UniversitÃ© de Nantes, France, 9DLR, Berlin, Germany, 10MPAE, Lindau, Germany, 11Earth & Planeraty Sciences, Washington University, Saint-Louis, MO 63130, USA, 12Geological Sciences, Brown University, Providence, RI 02912, USA, 13JPL, Pasadena, Ca, USA, 14LMD, UniversitÃ© de Paris 6, 75252, Paris, France

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Pierre Drossart (Observatoire de Paris, LESIA)

Last update on 21 December 2021

Repartition of H2O and CO2 ices on the south polar cap of Mars Observations OMEGA/Mars Express

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