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

Encrenaz, Thérèse; DeWitt, Curtis; Richter, Matthew J.; Greathouse, T. K.; Fouchet, Thierry; Montmessin, Franck; Lefèvre, Franck; Bézard, Bruno; Atreya, S. K.; Aoki, Shohei; Sagawa, Hideo

doi:10.1051/0004-6361/201732367

Cited by 38 publications

(38 citation statements)

References 21 publications

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“…On this planet, the D/H budget is dominated by H 2 O and HDO which are the unique precursors of the escaping D and H atoms above the exobase. HDO was previously measured as column-integrated abundances from Earth [31][32][33] and in situ 34 by the Mars Science Laboratory. NOMAD and ACS provide for the first time the capability to observe the vertical distribution of HDO simultaneously with water vapour, thereby providing key information on the fractionation processes that are expected to control the amount of hydrogen and deuterium atoms escaping to space 25 .…”

Section: The Fractionation Between H 2 O and Hdo Is An Important Procmentioning

confidence: 99%

Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

Vandaele¹,

Korablev²,

Daerden³

et al. 2019

Nature

137

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Section: The Fractionation Between H 2 O and Hdo Is An Important Procmentioning

confidence: 99%

Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

Vandaele¹,

Korablev²,

Daerden³

et al. 2019

Nature

137

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“…Similar trends have been found for properties of upper atmospheric hydrogen at Mars (Bhattacharyya et al, ; Clarke et al, , ; Halekas, ). Studies of water variability lower in the atmosphere, using spectral analysis of H 2 O and HDO as well as using simulations, have shown seasonal differences in the distribution of water and its isotopologues lower in the Martian atmosphere (Encrenaz et al, ; Encrenaz et al, ; Fedorova et al, ; Krasnopolsky, ; Montmessin et al, ; Villanueva et al, ).…”

Section: Discussionmentioning

confidence: 99%

Seasonal Variability of Deuterium in the Upper Atmosphere of Mars

et al. 2019

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Measurements by multiple Mars Atmosphere and Volatile Evolution mission instruments, obtained between November 2014 and November 2017, are analyzed to produce deuterium properties in the upper atmosphere of Mars. We show here, for the first time, the seasonal distribution and variability of D densities, temperatures, and estimated Jeans escape rates at the exobase (200 km). Within the data constraints, it is found that the variations in D properties are similar for the northern and southern hemispheres, and peak near southern summer solstice. Trends in the D Lyman-α brightness, temperature, density, and escape rate are increasing during the beginning of the dust storm season, peak near southern summer solstice, and decrease toward the end of the dust storm season. This suggests that seasonal drivers at Mars cause deuterium in the upper atmosphere to become globally enhanced when Mars is closest to the Sun and during the Martian dust season when water is provided to the upper atmosphere by subsurface, hydrological, and dust storm dynamics.Plain Language Summary Water escape at Mars can be examined by analyzing the properties of present day hydrogen and its isotope deuterium. The ratio of the abundance of these two atoms at the upper atmosphere of Mars can provide limitations to the preferential escape of one over the other and can provide information on the present rate of escape of water from the upper atmosphere. The results from this work can be paired with estimates of what early Mars and the Sun were like in order to provide estimates for the early water content on ancient Mars. In this paper, the most comprehensive set of observations of deuterium from Mars are analyzed, and the resulting properties of deuterium in the upper atmosphere of Mars are presented. Key Points:• Deuterium (D) emissions from the limb of Mars are analyzed to produce atomic abundances and escape rate estimates in the upper atmosphere • D property variations are pronounced. Brightness and densities increase with Mars' proximity to the Sun and peak near southern summer solstice • Variations of deuterium brightness, densities, and escape rates suggest a seasonally varying D/H ratio at MarsSupporting Information:• Supporting Information S1

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“…This led M05 to predict a latitudinal gradient of D/H (with variations greater than a factor of 5) between the warm and moist summer hemisphere and the cold and dry winter hemisphere. This gradient was later confirmed by several Earth ground-based and Mars orbiting assets (Aoki et al, 2019;Encrenaz et al, 2018;Krasnopolsky, 2015;Villanueva et al, 2015). Yet some observations (Khayat et al, 2019;Villanueva et al, 2015) have revealed longitudinal variations of D/H ratios in appearance correlated to topography that were not reproduced by any model.…”

mentioning

confidence: 87%

The Effect of the Martian 2018 Global Dust Storm on HDO as Predicted by a Mars Global Climate Model

Rossi

Vals

Montmessin

et al. 2021

Geophysical Research Letters

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The deuterium to hydrogen (D/H) ratio is commonly used to investigate the history of water on Mars, yet the mechanisms controlling present‐day HDO behavior are poorly understood. Significant variations of the D/H ratio were first predicted on the basis of a 3D global climate model, which were later confirmed by ground‐based observations. This behavior, consisting of lower HDO/H2O ratios in the colder regions of Mars, is related to the isotopic fractionation occurring at condensation. We leverage this previous effort and present an updated implementation, using the modern version of the model, that remains in agreement with the older version. We explore the impact of the global dust storm (GDS) that occurred during Martian year 34 (MY34) on HDO. Our simulations indicate that HDO is on average 40% more abundant at 100 km during the MY34 GDS year than during a regular year, with likely large consequences for the escape flux of water that year.

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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.

Cited by 38 publications

References 21 publications

Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

Martian dust storm impact on atmospheric H2O and D/H observed by ExoMars Trace Gas Orbiter

Seasonal Variability of Deuterium in the Upper Atmosphere of Mars

The Effect of the Martian 2018 Global Dust Storm on HDO as Predicted by a Mars Global Climate Model

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