Journal article
On Mars's Atmospheric Sputtering After MAVEN's First Martian Year of Measurements
Geophysical research letters, Vol.45(10), pp.4685-4691
05/28/2018
DOI: 10.1002/2018GL077199
Abstract
Mars likely lost a significant part of its atmosphere to space during its history. The sputtering of the atmosphere, by precipitating planetary heavy pickup ions accelerated by the solar wind, is one of the processes that could have significantly contributed to this atmospheric escape, in particular since the cessation of its global magnetic field, 4.0–4.1 Gyr ago. We present a 2 year baseline analysis of Mars Atmosphere and Volatile EvolutioN (MAVEN) observations of the precipitating flux. We use this measurement to model the expected escape rate and exospheric structure induced by this precipitation. We conclude that sputtering signatures in the dayside exosphere will be difficult to identify by MAVEN, and the induced atmospheric escape of O atoms remains orders of magnitude smaller than the expected rate induced by dissociative recombination of O2+ in Mars's ionosphere. On the contrary, deep in the nightside, Mars's sputtering might be the main source of the nonthermal part of the exospheric density profiles of species with mass larger or equal to Ar.
Plain Language Summary
After 2 years of Mars Atmosphere and Volatile EvolutioN measurements, it is possible to reconstruct the average precipitating heavy ion flux into Mars's atmosphere. These ions can lead to the sputtering of Mars's atmosphere, a process which might have eroded a significant part of Mars's atmosphere 4 Gyr ago. Today, it is much more difficult to identify a clear signature of this process. However, we here show that such signature might be found deep in the night according to models.
Key Points
Reconstruction of the average precipitating flux into Mars's atmosphere based on MAVEN's first 2 years of measurements is presented
Reconstruction of the sputtering contribution to Mars's exosphere using MAVEN‐measured precipitating flux is presented
A comparison with other sources of exosphere allows us to suggest where sputtering signatures in the exosphere might be detectable
Details
- Title: Subtitle
- On Mars's Atmospheric Sputtering After MAVEN's First Martian Year of Measurements
- Creators
- F Leblanc - Goddard Space Flight CenterA Martinez - Université Paris CitéJ. Y Chaufray - Université Paris CitéR Modolo - Université Paris-SaclayT Hara - University of California, BerkeleyJ Luhmann - University of California, BerkeleyR Lillis - University of California, BerkeleyS Curry - University of California, BerkeleyJ McFadden - University of California, BerkeleyJ Halekas - University of IowaB Jakosky - University of Colorado Boulder
- Resource Type
- Journal article
- Publication Details
- Geophysical research letters, Vol.45(10), pp.4685-4691
- DOI
- 10.1002/2018GL077199
- ISSN
- 0094-8276
- eISSN
- 1944-8007
- Number of pages
- 7
- Grant note
- Programme National de Planétologie CNES “Système Solaire” program MARMITE (ANR‐13‐BS05‐0012‐02) Programme National Soleil‐Terre ANR (ANR‐09‐BLAN‐0223)
- Language
- English
- Date published
- 05/28/2018
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199843802771
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