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Communication Dans Un Congrès Année : 2023

Sky Spectroscopy from the Perseverance and Curiosity Rovers: latest results and implications for explaining molecular oxygen variability

Timothy H. Mcconnochie
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Elise Wright Knutsen
Franck Montmessin
Roger C. Wiens
Mark T. Lemmon
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Michael J. Wolff
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Michael D. Smith
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Melissa G. Trainer
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Franck Lefèvre

Résumé

Both Perseverance and Curiosity conduct routine passive soundings of the Martian atmosphere by acquiring spectra of the sky in UV through near-IR wavelengths with the SuperCam and ChemCam instrument suites, respectively. Both SuperCam and ChemCam measure the column abundances of water vapor and O2, as well as aerosol properties, with these soundings. This presentation is both a status report on the results for all of these quantities, and an update on their implications for the problem of molecular oxygen variability substantially exceeding that of inert trace gases (Trainer et al. 2018, doi:10.1029/2019JE006175; Lo et al 2023, under revision). Molecular oxygen variability is 20 - 30% larger than expected from photochemical models, which indicate that it should behave as an inert trace gas on seasonal and annual time-scales, and the seasonal increase is so large that it appears to require a surface or subsurface reservoir capable of exchanging oxygen with the atmosphere on seasonal or shorter timescales, together with a mechanism for rapid decay of O2 (Trainer et al. 2018, doi:10.1029/2019JE006175; Lo et al 2023, under revision). Perchlorates/chlorates and related chemical cycles seems to be the best candidate for such a reservoir. UV flux and water vapor humidity may both be involved in determining the rates and directions of the required reactions (Klein, 1978; Carrier and Kounaves, 2015; Escamilla-Roa, et al., 2020) so correlating aerosol properties (which influence UV flux at the surface) and water vapor abundances with O2 variability may, when combined with global circulation modeling, help constrain the nature of the chemistry. Dust cycle and water cycle measurement campaigns involve numerous other rover and orbiter instruments, but SuperCam and ChemCam sky spectroscopy is particularly valuable for its ability to distinguish dust aerosol from ice clouds over the rovers, and for its ability to capture the daytime portion of the local water cycle. Comparing the direct measurements of the O2 column by SuperCam with those of ChemCam (e.g. McConnochie et al., 2021, AGU Fall Meeting) will also help constrain the chemistry of O2 variability, in this case by comparing the timing and magnitude of anomalous behavior in different locations to offer clues about source and sink regions and associated environmental conditions.
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Dates et versions

insu-04368394 , version 1 (31-12-2023)

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  • HAL Id : insu-04368394 , version 1

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Timothy H. Mcconnochie, Tanguy Bertrand, Elise Wright Knutsen, Franck Montmessin, Thierry Fouchet, et al.. Sky Spectroscopy from the Perseverance and Curiosity Rovers: latest results and implications for explaining molecular oxygen variability. AGU Fall Meeting 2023, Dec 2023, San Francisco (Califonia), United States. ⟨insu-04368394⟩
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