Please use this identifier to cite or link to this item:
Title: Day-night differences in Mars methane suggest nighttime containment at Gale crater
Authors: Webster, C. R.
Mahaffy, Paul R.
Pla García, J.
Rafkin, S. C. R.
Moores, J. E.
Atreya, S. K.
Flesch, G. J.
Malespin, C. A.
Teinturier, S. M.
Kalucha, H.
Smith, C. L.
Viúdez Moreiras, Daniel
Vasavada, A. R.
Keywords: Techniques: spectroscopic;Planets and satellites: atmospheres;Planets and satellites: composition
Issue Date: 29-Jun-2021
Publisher: EDP Sciences
DOI: 10.1051/0004-6361/202040030
Published version:
Citation: Astronomy and Astrophysics 650: A166(2021)
Abstract: We report new measurements of atmospheric methane by the Curiosity rover’s Tunable Laser Spectrometer that is part of the Sample Analysis at Mars suite (TLS-SAM), finding nondetections during two daytime measurements of average value 0.05 ± 0.22 ppbv (95% confidence interval CI). These are in marked contrast with nighttime background levels of 0.52 ± 0.10 (95% CI) from four measurements taken during the same season of northern summer. This large day-night difference suggests that methane accumulates while contained near the surface at night, but drops below TLS-SAM detection limits during the day, consistent with the daytime nondetection by instruments on board the ExoMars Trace Gas Orbiter. With no evidence for methane production by the rover itself, we propose that the source is one of planetary micro-seepage. Dynamical modeling indicates that such methane release is contained within the collapsed planetary boundary layer (PBL) at night due to a combination of nocturnal inversion and convergent downslope flow winds that confine the methane inside the crater close to the point where it is released. The methane abundance is then diluted during the day through increased vertical mixing associated with a higher altitude PBL and divergent upslope flow that advects methane out of the crater region. We also report detection of a large spike of methane in June 2019 with a mean in situ value over a two-hour ingest of 20.5 ± 4 ppbv (95% CI). If near-surface production is occurring widely across Mars, it must be accompanied by a fast methane destruction or sequestration mechanism, or both.
E-ISSN: 1432-0746
ISSN: 0004-6361
Appears in Collections:(CAB) Artículos

Files in This Item:
File Description SizeFormat 
Day night differences in Mars methane suggest nighttime containment at Gale crater.pdf6,63 MBAdobe PDFThumbnail

This item is licensed under a Creative Commons License Creative Commons