New measurements of D/H on Mars using EXES aboard SOFIA

Abstract : The global D/H ratio on Mars is an important measurement for understanding the past history of water on Mars; locally, through condensation and sublimation processes, it is a possible tracer of the sources and sinks of water vapor on Mars. Measuring D/H as a function of longitude, latitude and season is necessary for determining the present averaged value of D/H on Mars. Following an earlier measurement in April 2014, we used the Echelon Cross Echelle Spectrograph (EXES) instrument on board the Stratospheric Observatory for Infrared Astronomy (SOFIA) facility to map D/H on Mars on two occasions, on March 24, 2016 (Ls = 127°), and January 24, 2017 (Ls = 304°), by measuring simultaneously the abundances of H2O and HDO in the 1383–1391 cm−1 range (7.2 μm). The D/H disk-integrated values are 4.0 (+0.8, −0.6) × Vienna Standard Mean Ocean Water (VSMOW) and 4.5 (+0.7, −0.6) × VSMOW, respectively, in agreement with our earlier result. The main result of this study is that there is no evidence of strong local variations in the D/H ratio nor for seasonal variations in the global D/H ratio between northern summer and southern summer.
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Submitted on : Monday, May 28, 2018 - 9:08:25 AM
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Thérèse Encrenaz, C. Dewitt, M. Richter, T. Greathouse, Thierry Fouchet, et al.. New measurements of D/H on Mars using EXES aboard SOFIA. Astronomy and Astrophysics - A&A, EDP Sciences, 2018, 612, A112 (13 p.). ⟨10.1051/0004-6361/201732367⟩. ⟨insu-01800799⟩

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