The Methane Diurnal Variation and Microseepage Flux at Gale Crater, Mars as Constrained by the ExoMars Trace Gas Orbiter and Curiosity Observations

Moores, John E.; King, P. L.; Smith, C. L.; Martínez, G.; Newman, Claire; Guzewich, Scott D.; Meslin, Pierre‐Yves; Webster, Christopher R.; Mahaffy, P. R.; Atreya, S. K.; Schuerger, Andrew C.

doi:10.1029/2019gl083800

Cited by 44 publications

(56 citation statements)

References 32 publications

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“…In fact, summarizing the results of the previous observations, the source of Mars methane should be spatially restricted but also temporarily restricted with potential sources in form of seepages (Yung et al, 2018): from micro-seepages, (Etiope et al, 2015;Moores et al, 2019), mini-seepages (Etiope et al, 2015) to macro-seepages, (Oehler et al, 2017). Furthermore, the different amounts detected in spikes Table 1, seasonal oscillations and non-detections are compatible with geological seepage dynamics that involve changes in gradient of pressure and in the permeability of rocks (Etiope and Oehler, 2019).…”

Section: Instead the 3 Years Measurements Of Mars Surface Laboratorymentioning

confidence: 82%

Investigation on the Absorption Bands Around 3.3 μm in CRISM Data

Manzari

Marzo

Ammannito

2020

Preprint

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Recently, the methane seepage detected by Mars Sample Laboratory (MSL) in the Gale crater area during 2013 was confirmed by methane detection by the Planetary Fourier Spectrometer (PFS). While analyzing NIR-IR CRISM data on a site in Oxia Planum area, in the view of a future comparison with data that will be collected by the Rosalind Franklin rover onboard the ExoMars2022 mission, a 3.3 μm absorption was noted in some pixel spectra. Since methane, like other hydrocarbons, shows absorptions in the range 3.1-3.6 μm, we begun to study this band in CRISM data to explore the possibility to look for seepages on Mars surface. The datasets chosen for this study, aside the site in Oxia Planum area, include some sites of observations on Gale Crater and other sites in Nili Fossae area. We used the Planetary Spectrum Generator to simulate CRISM spectra of the different sites, with the diverse concentrations of CH4 spikes. These simulations served to establish the relation between concentration and methane band depths, as seen by CRISM spectrometer. Then, mapping the Modified Gaussian Model fit on CRISM data, we extracted the band parameters of the absorptions in the 3.3 μm spectral region. Aside rare, suspected absorptions, an artifact was highlighted. Therefore, we have set a threshold on the depth to consider as depth of potential true absorptions, on the basis of the standard deviation (s) of absorption depth map. Finally, we concluded to favor as potential absorptions: distribution of clusters of pixels in the band mapping not vertically stacked and a threshold value >μ (average)+5σ (standard deviation) of the depth map. These threshold values set the lower limit for each observation on the methane concentration potentially detectable by CRISM. The threshold value varies from one observation to another, in a range between 0.0136-0.0237, that would correspond in a range of lower limit concentrations of 180 and 600 ppbv. We found interesting cluster of pixels which spectra overcome the imposed threshold. We still consider that part of them could still be a kind of unknown artifact. Nevertheless, the aim of this paper is to show that CRISM data can show potential absorptions of methane in such quantities that in some observations are compatible with the order of the methane spikes effectively detected in literature. Even if this work does not confirm nor deny the occurrences of methane seepages in the investigated images it shows a possible method for assessing a confidence limit in the detection of this band in CRISM data.

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Section: Instead the 3 Years Measurements Of Mars Surface Laboratorymentioning

confidence: 82%

Investigation on the Absorption Bands Around 3.3 μm in CRISM Data

Manzari

Marzo

Ammannito

2020

Preprint

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“…Detections of tiny amounts of CH4 in Mars' present-day atmosphere have been reported (e.g. Webster et al 2018), although these detections do not all agree with one another and are in tension with models that predict lower methane abundance, and also lower methane abundance variability, than has been reported (Zahnle et al 2011, Mischna et al 2011, Korablev et al 2019, Zahnle & Catling 2019, Moores et al 2019. Separate from its potential to warm Mars, methane can also serve as the feedstock for photochemical production of complex organic matter -hazes and soots.…”

Section: Causes and Effects Of Methane Release On Early Marsmentioning

confidence: 95%

Methane release on Early Mars by atmospheric collapse and atmospheric reinflation

Kite

Mischna

Yung

et al. 2020

Planetary and Space Science

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Please cite this article as: Kite, E.S., Mischna, M.A., Gao, P., Yung, Y.L., Turbet, M., Methane release on Early Mars by atmospheric collapse and atmospheric reinflation, Planetary and Space Science (2020), doi: https://doi. Abstract.A candidate explanation for Early Mars rivers is atmospheric warming due to surface release of H2 or CH4 gas. However, it remains unknown how much gas could be released in a single event. We model the CH4 release by one mechanism for rapid release of CH4 from clathrate. By modeling how CH4-clathrate release is affected by changes in Mars' obliquity and atmospheric composition, we find that a large fraction of total outgassing from CH4 clathrate occurs following Mars' first prolonged atmospheric collapse. This atmosphere-collapse-initiated CH4-release mechanism has three stages. (1) Rapid collapse of Early Mars' carbon dioxide atmosphere initiates a slower shift of water ice from high ground to the poles.(2) Upon subsequent CO2-atmosphere re-inflation and CO2-greenhouse warming, low-latitude clathrate decomposes and releases methane gas. (3) Methane can then perturb atmospheric chemistry and surface temperature, until photochemical processes destroy the methane.Within our model, we find that under some circumstances a Titan-like haze layer would be expected to form, consistent with transient deposition of abundant complex abiotic organic matter on the Early Mars surface. We also find that this CH4release mechanism can warm Early Mars, but special circumstances are required in order to uncork 10 17 kg of CH4, the minimum needed for strong warming. Specifically, strong warming only occurs when the fraction of the hydrate stability zone that is initially occupied by clathrate exceeds 10%, and when Mars' first prolonged atmospheric collapse occurs for atmospheric pressure > 1 bar.

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“…There is considerable debate in the community about the validity and robustness of detections of atmospheric methane (CH 4 ) on Mars. Detections and nondetections of atmospheric CH 4 have been reported using data collected by satellites (Formisano et al., 2004; Fonti & Marzo, 2010; Geminale et al., 2008, 2011; Giuranna et al., 2019), Earth‐based telescopes (Krasnopolsky, 2007, 2011, 2012; Krasnopolsky et al., 1997, 2004; Mumma et al., 2009; Villanueva et al., 2013), and in situ instruments (Moores et al., 2019; Webster et al., 2015, 2018). This debate highlights the difficulty of measuring atmospheric CH 4 on Mars and the gaps in our current understanding of the production and loss terms that determine atmospheric CH 4 on Mars.…”

Section: Introductionmentioning

confidence: 99%

Photochemistry of Methane and Ethane in the Martian Atmosphere

Taysum

Palmer

2020

JGR Planets

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We develop an existing 1‐D photochemistry model to include a comprehensive description of organic chemistry on Mars that includes the oxidation products of methane (CH4) and ethane (C2H6),a longer‐chain hydrocarbon that can be used to differentiate between abiotic and biotic surface releases of CH4. We find that CH4 is most volatile between 20 and 50 km during Mars' northern summer, where the local atmospheric CH4 lifetime lowers to 25–60 years. We study atmospheric formaldehyde (HCHO) and formic acid (HCOOH), as the two common oxidation products of CH4 and C2H6, and acetaldehyde (CH3CHO) and acetic acid (CH3COOH) as unique products of C2H6. We focus our analysis of these gases at Mars' aphelion and perihelion at latitudes between ‐30° and 30°, altitudes from the surface to 70 km, and from a homogeonous initial condition of 50 pptv of CH4 and C2H6. From this initial condition, CH4 produces HCHO in a latitude‐independent layered structure centered at 20–30 km at aphelion with column‐averaged mixing ratios of 10−4 pptv, and oxidation of C2H6 produces HCHO at 10−2 pptv. Formic acid has an atmospheric lifetime spanning 1–10 sols below 10 km that shows little temporal or zonal variability and is produced in comparable abundances (10−5 pptv) by the oxidation of C2H6 and CH4. We also find that oxidation of 50 pptv of C2H6 results in 10−3 pptv of CH3CHO and 10−4 pptv of CH3COOH. Subsequent UV photolysis of this CH3CHO results in 10−4 pptv of atmospheric CH4, potentially representing a new atmospheric source of Martian CH4.

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The Methane Diurnal Variation and Microseepage Flux at Gale Crater, Mars as Constrained by the ExoMars Trace Gas Orbiter and Curiosity Observations

Cited by 44 publications

References 32 publications

Investigation on the Absorption Bands Around 3.3 μm in CRISM Data

Investigation on the Absorption Bands Around 3.3 μm in CRISM Data

Methane release on Early Mars by atmospheric collapse and atmospheric reinflation

Photochemistry of Methane and Ethane in the Martian Atmosphere

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