The Highly Variable Ratio of D/H in Atoms Escaping from Mars - INSU - Institut national des sciences de l'Univers Accéder directement au contenu
Communication Dans Un Congrès Année : 2020

The Highly Variable Ratio of D/H in Atoms Escaping from Mars

Résumé

The constituent atoms of water are known to escape the weak Martian gravity into space, and the lighter isotope H escapes faster than D leading to a long term increase in the D/H ratio of the remaining water. The present D/H ratio is proportional to the total amount of water that has escaped, but deriving the depth of water on a warmer and wetter primordial Mars requires understanding the factors that control escape processes today. In particular, it is important to measure the escaping atoms H and D, rather than rely on the D/H ratio in water and modeling. Observations of UV Lyman-alpha resonance line emissions from H and D atoms has been carried out with the MAVEN and Hubble Space Telescope (HST) missions, providing direct measurements of the H and D densities and escape rates from the upper Martian atmosphere. The H and D densities and the ratio of D/H in the escaping atoms are found to consistently increase by a factor of 5-10 around southern summer (perihelion) across several Martian years. This is consistent with an influx of hydrogen species from lower atmospheric water around perihelion, at which times the D/H ratio also increases from the higher escape flux of H compared with the heavier D atoms. A scenario is proposed to explain these changes that can be verified by future measurements.
Fichier non déposé

Dates et versions

insu-04418110 , version 1 (25-01-2024)

Identifiants

Citer

J. T. Clarke, M. Mayyasi, D. Bhattacharyya, N. M. Schneider, B. M. Jakosky, et al.. The Highly Variable Ratio of D/H in Atoms Escaping from Mars. American Geophysical Union, Fall Meeting 2020, Dec 2020, Online, Unknown Region. pp.abstract #P033-0018. ⟨insu-04418110⟩
19 Consultations
0 Téléchargements

Partager

Gmail Facebook X LinkedIn More