Background levels of methane in Mars’ atmosphere show strong seasonal variations

Webster, Christopher R.; Mahaffy, P. R.; Atreya, S. K.; Moores, John E.; Flesch, Gregory J.; Malespin, C. A.; McKay, Christopher P.; Martínez, G.; Smith, C. L.; Martín‐Torres, Javier; Gómez‐Elvira, Javier; Zorzano, María Paz; Wong, Michael H.; Trainer, M. G.; Steele, A.; Archer, P. D.; Sutter, B.; Coll, Patrice; Freissinet, Caroline; Meslin, Pierre‐Yves; Gough, R. V.; House, Christopher H.; Pavlov, Alexander A.; Eigenbrode, J. L.; Glavin, Daniel P.; Pearson, John C.; Keymeulen, Didier; Christensen, L. E.; Schwenzer, S. P.; Navarro‐González, Rafael; Pla‐García, Jorge; Rafkin, Scot; Vicente‐Retortillo, Á.; Kahanpää, Henrik; Viúdez‐Moreiras, Daniel; Smith, M. D.; Harri, A. M.; Genzer, M.; Hassler, Donald M.; Lemmon, M. T.; Crisp, J. A.; Sander, Stanley P.; Zurek, Richard W.; Vasavada, A. R.

doi:10.1126/science.aaq0131

Cited by 246 publications

(212 citation statements)

References 56 publications

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“…It is therefore unlikely that outgassing of the source sediments is still active. Although processes associated with subsurface sediment mobilization are often proposed as the possible source of atmospheric methane (e.g., Oehler & Etiope, ), our findings do not support a direct link of the formation of the studied features to the atmospheric methane that has been recently reported (Webster et al, ).…”

Section: Discussioncontrasting

confidence: 99%

“…Ever since the presence of methane in the Martian atmosphere was reported from ground‐based, orbital, and in situ observations (Formisano et al, ; Geminale et al, ; Krasnopolsky et al, ; Mumma et al, ; Webster et al, ), mud volcanism was hypothesized to be a possible release mechanism (reviewed by Oehler & Etiope, ), and various mud volcano fields have been tentatively identified (Allen et al, ; Hemmi & Miyamoto, ; Komatsu et al, ; Oehler & Allen, ; Okubo, ; Pondrelli et al, ; Salvatore & Christensen, ; Skinner & Mazzini, ; Skinner & Tanaka, ). It is difficult, however, to define diagnostic morphological properties of mud volcanism in remote sensing data (Oehler & Allen, ), and some of the reported mud volcanoes have alternatively been interpreted as igneous volcanoes (Brož & Hauber, ; Brož et al, ).…”

Section: Introductionmentioning

confidence: 99%

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Subsurface Sediment Mobilization in the Southern Chryse Planitia on Mars

et al. 2019

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The southern part of the smooth plain of Chryse Planitia on Mars hosts a large population of kilometer‐sized (from ~0.2 to ~20 km) landforms spread over a wide area. Based on the investigation of a small part of this area, Komatsu et al. (2016, https://doi.org/10.1016/j.icarus.2015.12.032) proposed that the edifices may be the result of the subsurface sediment mobilization. We mapped the full extent of these landforms within Chryse Planitia and performed a morphological and spatial analysis in an attempt to further test this hypothesis. We identified a total number of 1,318 of these objects, which we grouped into five different morphological classes. The edifices can be observed over an area of 700,000 km2 near the termini of the large outflow channels, Ares, Simud, and Tiu Valles, with a nonrandom spatial distribution. The features are clustered and anticorrelated to the ancient highlands, which form erosional remnants shaped by the outflow events. This suggests a genetic link between the distribution of the edifices and the presence of the sedimentary deposits on which they are superposed. Such distribution is consistent with the previous notion that subsurface sediment mobilization may be the mechanism for their formation and is less consistent with the alternative igneous volcanic hypothesis. We also propose a scenario in which the large morphologic variability can be explained by variations of the water content within the ascending mud and by variations in the effusion rates. The edifices may represent one of the most prominent fields of sedimentary volcanism detected on Mars.

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Section: Discussioncontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Subsurface Sediment Mobilization in the Southern Chryse Planitia on Mars

et al. 2019

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“…; Webster et al. ), opening the possibility that life may exist on modern Mars. If life arose on early Mars, it either adapted to the current extreme conditions or went extinct (Ulrich et al.…”

Section: Objective 2: Assess and Interpret The Potential Biological Hmentioning

confidence: 99%

“…4.5, measurements of methane have also been variable (Webster et al. , ), with at least part of the variation correlated with time of the year (Webster et al. ).…”

Section: Objective 4: Constrain the Inventory Of Martian Volatiles Asmentioning

confidence: 99%

“…In the first place, mapping of trace gas distribution and concentration in time and space around Mars (e.g., Webster et al. ) by the TGO will be an important input into choosing the timing of collecting the surface gas samples described below under Objective 4. The planetary‐scale surveys of trace gas concentrations as a function of time, especially methane, will establish the context for interpreting the analytic data collected on the returned gas samples.…”

Section: Introductionmentioning

confidence: 99%

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The potential science and engineering value of samples delivered to Earth by Mars sample return

Beaty¹,

Grady²,

McSween³

et al. 2019

Meteorit & Planetary Scien

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Executive Summary Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the team is to re‐evaluate and update the sample‐related science and engineering objectives of a Mars Sample Return (MSR) campaign. The iMOST team has also undertaken to define the measurements and the types of samples that can best address the objectives. Seven objectives have been defined for MSR, traceable through two decades of previously published international priorities. The first two objectives are further divided into sub‐objectives. Within the main part of the report, the importance to science and/or engineering of each objective is described, critical measurements that would address the objectives are specified, and the kinds of samples that would be most likely to carry key information are identified. These seven objectives provide a framework for demonstrating how the first set of returned Martian samples would impact future Martian science and exploration. They also have implications for how analogous investigations might be conducted for samples returned by future missions from other solar system bodies, especially those that may harbor biologically relevant or sensitive material, such as Ocean Worlds (Europa, Enceladus, Titan) and others. Summary of Objectives and Sub‐Objectives for MSR Identified by iMOST This objective is divided into five sub‐objectives that would apply at different landing sites. 1.1 Characterize the essential stratigraphic, sedimentologic, and facies variations of a sequence of Martian sedimentary rocks. 1.2 Understand an ancient Martian hydrothermal system through study of its mineralization products and morphological expression. 1.3 Understand the rocks and minerals representative of a deep subsurface groundwater environment. 1.4 Understand water/rock/atmosphere interactions at the Martian surface and how they have changed with time. 1.5 Determine the petrogenesis of Martian igneous rocks in time and space. This objective has three sub‐objectives: 2.1 Assess and characterize carbon, including possible organic and pre‐biotic chemistry. 2.2 Assay for the presence of biosignatures of past life at sites that hosted habitable environments and could have preserved any biosignatures. 2.3 Assess the possibility that any life forms detected are alive, or were recently alive. Summary of iMOST Findings Several specific findings were identified during the iMOST study. While they are not explicit recommendations, we suggest that they should serve as guidelines for future decision making regarding planning of potential future MSR missions. The samples to be collected by the Mars 2020 (M‐2020) rover will be of sufficient size and quality to address and solve a wide variety of scientific questions. Samples, by definition, are a statistical representation of a larger entity...

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Arsenic‐and Light Hydrocarbon‐Rich Hypersaline Soda Lakes and Their Resident Microbes as Possible Models for Extraterrestrial Biomes

Oremland¹

2020

Extremophiles as Astrobiological Models

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Background levels of methane in Mars’ atmosphere show strong seasonal variations

Cited by 246 publications

References 56 publications

Subsurface Sediment Mobilization in the Southern Chryse Planitia on Mars

Subsurface Sediment Mobilization in the Southern Chryse Planitia on Mars

The potential science and engineering value of samples delivered to Earth by Mars sample return

Arsenic‐and Light Hydrocarbon‐Rich Hypersaline Soda Lakes and Their Resident Microbes as Possible Models for Extraterrestrial Biomes

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