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Latitudinal And Seasonal Variations Of O2 And D/H On Mars Using Herschel/hifi

Therese Encrenaz 1 R. Moreno 1 E. Lellouch 1 T. Fouchet 1 P. Hartogh 2 C. Jarchow 2 Franck Lefèvre 3 T. Cavalié 4
LATMOS - Laboratoire Atmosphères, Milieux, Observations Spatiales
4 SSE 2012
L3AB - Laboratoire d'astrodynamique, d'astrophysique et d'aéronomie de bordeaux, OASU - Observatoire aquitain des sciences de l'univers, LAB - Laboratoire d'Astrophysique de Bordeaux [Pessac], Université Sciences et Technologies - Bordeaux 1
Abstract : As a non-condensible species, molecular oxygen on Mars is expected to show spatial and temporal variations, but these measurements have not been performed yet. In addition, mapping the D/H ratio and recording its seasonal variations is a key diagnostic for understanding the past history of water on Mars, as well as surface/atmosphere exchange in the water cycle (Montmessin et al. JGR 110, E3, CiteID E03006, 2005). We have been using HIFI abord Herschel to study the latitudinal variations of O2 and D/H on Mars for two different seasons, Ls = 47° (Dec. 23, 2011) and Ls = 108-115° (May 09-25, 2012). Three sets of transitions have been recorded : H218O and HDO around 1630 GHz, O2 and HDO around 1815 GHz, and 13CO and CO18 around 1870 GHz. The diameter of Mars was 8.3 arcsec on Dec. 23, 2011, and 8-9 arcsec in May 2012. The Herschel field of view is 11.3 arcsec at 1870 GHz and 9.8 arcsec at 1630 GHz. For each period, three observations were successively recorded, centered along the central meridian, at the south limb, the center and the north limb. The total observing time, over the two periods, was 26 hours. A preliminary reduction indicates a mean O2 abundance in agreement with previous measurements (1400 ppm, Hartogh et al. AA 521, id.L49, 2010). No significant variation is observed in O2 and CO between North and South for Ls = 47°, as expected in the vicinity of equinox (Forget et al. LPI-1494, 2009). An analysis of the two data sets will be presented.
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Therese Encrenaz, R. Moreno, E. Lellouch, T. Fouchet, P. Hartogh, et al.. Latitudinal And Seasonal Variations Of O2 And D/H On Mars Using Herschel/hifi. American Astronomical Society, 44th DPS Meeting 2012, Oct 2012, Reno, United States. ⟨hal-00822171⟩



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