Chaotic obliquity and the nature of the Martian climate

Jakosky, B. M.; Henderson, Bradley G.; Mellon, M. T.

doi:10.1029/94je02801

Cited by 155 publications

(127 citation statements)

References 34 publications

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“…According to Jakosky et al (1995), several of the various ternary salt waters had freezing points below 225 K and Martian brines may have existed in the past and even now. Therefore, if seepage groundwater is in pure H 2 O form, or contains only sulfate and chloride salts, the water would likely freeze while seeping to the surface of presentday Mars.…”

Section: Potential Antifreeze Compoundsmentioning

confidence: 99%

Potential Antifreeze Compounds in Present-Day Martian Seepage Groundwater

Jean¹,

Yang²,

Lee³

et al. 2008

Terr. Atmos. Ocean. Sci.

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Is the recently found seepage groundwater on Mars pure H 2 O, or mixed with salts and other antifreeze compounds? Given the surface conditions of Mars, it is unlikely that pure water could either exist in its liquid state or have shaped Mars' fluid erosional landforms (gullies, channels, and valley networks). More likely is that Mars' seepage groundwater contains antifreeze and salt compounds that resist freezing and suppress evaporation. This model better accounts for Mars' enigmatic surface erosion. This paper suggests 17 antifreeze compounds potentially present in Martian seepage groundwater. Given their liquid state and physical properties, triethylene glycol, diethylene glycol, ethylene glycol, and 1,3-propylene glycol are advanced as the most likely candidate compounds. This paper also explores how a mixing of glycol or glycerol with salts in the Martian seepage groundwater may have lowered water's freezing point and raised its boiling point, with consequences that created fluid gully and channel erosion. Ethylene glycol and related hydrocarbon compounds have been identified in Martian and other interstellar meteorites. We suggest that these compounds and their proportions to water be included for detection in future explorations.

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Section: Potential Antifreeze Compoundsmentioning

confidence: 99%

Potential Antifreeze Compounds in Present-Day Martian Seepage Groundwater

Jean¹,

Yang²,

Lee³

et al. 2008

Terr. Atmos. Ocean. Sci.

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“…[82] If the polar caps contain a significant amount of CO 2 clathrate admixed with water ice [Jakosky et al, 1995;Hoffman, 2000], then because CO 2 clathrate has a lower thermal conductivity and is stable under higher pressures than pure water ice, the cap would not melt as readily as it would if composed of pure water ice. Thus, obtaining an accurate estimate of the amount of CO 2 clathrate in the layered deposits would help constrain the conditions necessary for melting the deposits.…”

Section: Outstanding Questionsmentioning

confidence: 99%

Chasma Boreale, Mars: Topographic characterization from Mars Orbiter Laser Altimeter data and implications for mechanisms of formation

Fishbaugh

2002

J. Geophys. Res.

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[1] Chasma Boreale, a large reentrant in the north polar cap of Mars, is distinct in scale, detailed topography, and orientation from the spiraling troughs that characterize the majority of the polar cap. We use new, high-resolution Mars Orbiter Laser Altimeter (MOLA) data and Mars Orbiter Camera (MOC) and Viking images of the chasma region to assess hypotheses of origin of Chasma Boreale. These hypotheses include formation by glacial flow and ablation, by eolian processes (such as katabatic winds) and sublimation, by outflow of meltwater, or by a combination of two or more of these processes. We find that these new data support initial formation by outflow of meltwater with later modification by katabatic winds and sublimation. On the basis of our analysis we suggest a possible scenario in which outflow has occurred in several stages. The outflow appears to have begun near an enclosed depression at the head of the chasma; meltwater migrated within and below the ice down the regional slope and eventually broke out to the surface. Removal of material by melting caused subsidence and erosion of the polar deposits forming the chasma, which has subsequently undergone modification by eolian and sublimation processes. The outflow deposited most of its sediment in the form of a lobe that stratigraphically overlies the polygonal plains mapped at the mouth of the chasma and scoured some of the circumpolar sediment mantle in the surrounding region. The lowest portions of the North Polar Basin received the rest of the sediment as a deposit a few meters thick. MOLA data also reveal evidence for similar events of smaller magnitude elsewhere on the margins of the polar cap.

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“…Several studies have suggested gas hydrate dissociation as a mechanism for forming surface erosional features [Hoffman, 2000;Max and Clifford, 2001], and as significant subsurface or polar reservoirs of ancient water, CO 2 , and CH 4 which may have contributed to a thicker greenhouse atmosphere early in Martian history [Jakosky et al, 1995;Miller and Smythe, 1970;Prieto-Ballesteros et al, 2006]. The likelihood of large-scale CH 4 or CO 2 hydrate deposits in the nearsubsurface, however, has been questioned based on thermal conductivity calculations [Mellon, 1996].…”

Section: Introductionmentioning

confidence: 99%

Salinity‐induced hydrate dissociation: A mechanism for recent CH₄ release on Mars

Madden¹,

Ulrich²,

Onstott³

et al. 2007

Geophysical Research Letters

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[1] Recent observations of CH 4 in the Martian atmosphere suggest that CH 4 has been added relatively recently. Several mechanisms for recent CH 4 release have been proposed including subsurface biological methanogenesis, abiogenic hydrothermal and/or volcanic activity, dissociation of CH 4 hydrates, atmospheric photolysis, or addition of organics via bolide impact. This study examines the effects of increasing salinity on gas hydrate stability and compares estimates of the Martian geothermal gradient to CH 4 and CO 2 hydrate stability fields in the presence of high salinity brines. The results demonstrate that salinity increases alone result in a significant decrease in the predicted hydrate stability zone within the Martian subsurface and may be a driving force in CH 4 hydrate destabilization. Active thermal and/or pressure fluctuations are not required in order for CH 4 hydrates to be the source of atmospheric CH 4 . Citation: Elwood Madden, M. E., S. M. Ulrich, T. C. Onstott, and T. J. Phelps (2007), Salinity-induced hydrate dissociation: A mechanism for recent

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Chaotic obliquity and the nature of the Martian climate

Cited by 155 publications

References 34 publications

Potential Antifreeze Compounds in Present-Day Martian Seepage Groundwater

Potential Antifreeze Compounds in Present-Day Martian Seepage Groundwater

Chasma Boreale, Mars: Topographic characterization from Mars Orbiter Laser Altimeter data and implications for mechanisms of formation

Salinity‐induced hydrate dissociation: A mechanism for recent CH₄ release on Mars

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Chaotic obliquity and the nature of the Martian climate

Cited by 155 publications

References 34 publications

Potential Antifreeze Compounds in Present-Day Martian Seepage Groundwater

Potential Antifreeze Compounds in Present-Day Martian Seepage Groundwater

Chasma Boreale, Mars: Topographic characterization from Mars Orbiter Laser Altimeter data and implications for mechanisms of formation

Salinity‐induced hydrate dissociation: A mechanism for recent CH4 release on Mars

Contact Info

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Salinity‐induced hydrate dissociation: A mechanism for recent CH₄ release on Mars