Long term evolution and chaotic diffusion of the insolation quantities of Mars

Laskar, Jacques; Correia, A. C. M.; Gastineau, Mickaël; Joutel, F.; Levrard, Benjamin; Robutel, Philippe

doi:10.1016/j.icarus.2004.04.005

Cited by 853 publications

(798 citation statements)

References 68 publications

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“…It is interpreted to be composed of water ice condensed from the atmosphere that includes and is overlain by fine air fall dust. The mantle is geologically very recent and is thought to be deposited and removed cyclically as a result of episodic climate change driven by orbital dynamics, in particular variations in the obliquity of Mars rotation (Laskar et al, 2004). This hypothesis is compelling in that the total latitudinal extent of the mantle is very well anti-correlated with the TAR distribution.…”

Section: Sediment Source and Spatial Distributionmentioning

confidence: 99%

Transverse Aeolian Ridges (TARs) on Mars

et al. 2008

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Aeolian processes are probably the dominant ongoing surface process on Mars; Large Dark Dunes (LDDs), particularly common aeolian landforms, were first recognized in the early 1970s. Recent, higher resolution images have revealed another, morphologically distinct, large population of smaller, ripple-like aeolian bedforms that have been termed "Transverse Aeolian Ridges" (TARs) as it is unknown whether they formed as large ripples or small dunes. We have begun a new study of TARs that examines their distribution, orientation, and morphology using N 10,000 high-resolution Mars Orbiter Camera (1.5 to 8 m/pixel resolution) images in a 45°longitude wide, pole-to-pole survey. The aim of this study is to assess whether TARs are active, to identify possible sediment sources and pathways, and to determine the volumes of sediment that they comprise. We present results from the first half of this study, in which we examine the northern hemisphere, and describe a new three-part classification scheme used to aid the survey. Our results show that TARs are abundant but not ubiquitous: preferentially forming proximal to friable, layered terrains such as those found in Terra Meridiani -the location of the ongoing Mars Exploration Rover "Opportunity" mission. TAR distribution in the northern hemisphere shows a strong latitudinal dependence with very few TARs being found north of ∼ 30°N. We also find that in most cases TARs are less mobile than LDDs, a conclusion possibly explained by Mars Exploration Rover Opportunity observations that show TARlike ripples to have a core of fine material armored by a monolayer of granule-sized particles. This could disallow significant bedform movement under the current wind regime. That TARs are essentially inactive is confirmed by superposition relations with slope streaks and LDDs and by observations of superposed impact craters. We suggest that observations made by the Opportunity Rover in Terra Meridiani indicate that the small aeolian bedforms common here are ripples and not small dunes. Farther south, these bedforms transition into larger features indistinguishable from TARs, suggesting that TARs (in the Meridiani area at least) are ripples and not dunes.

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Section: Sediment Source and Spatial Distributionmentioning

confidence: 99%

Transverse Aeolian Ridges (TARs) on Mars

et al. 2008

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“…Mars' obliquity, or axial tilt, is centred around roughly the same angle as Earth's 28 , though known to vary by as much as ± 20°more over intermediate timescales (B5-10 Myr ago). Although obliquity is thought to have varied significantly more and in chaotic ways over longer timescales 29 , addressing how these variations might affect insolation-related cracking is beyond the scope of this paper.…”

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confidence: 99%

Cracks in Martian boulders exhibit preferred orientations that point to solar-induced thermal stress

et al. 2015

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The origins of fractures in Martian boulders are unknown. Here, using Mars Exploration Rover 3D data products, we obtain orientation measurements for 1,857 cracks visible in 1,573 rocks along the Spirit traverse and find that Mars rock cracks are oriented in statistically preferred directions similar to those compiled herein for Earth rock cracks found in mid-latitude deserts. We suggest that Martian directional cracking occurs due to the preferential propagation of microfractures favourably oriented with respect to repeating geometries of diurnal peaks in sun-induced thermal stresses. A numerical model modified here with Mars parameters supports this hypothesis both with respect to the overall magnitude of stresses as well as to the times of day at which the stresses peak. These data provide the first direct field and numerical evidence that insolation-related thermal stress potentially plays a principle role in cracking rocks on portions of the Martian surface.

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“…During the last 10 Myr, it has been as low as 15 • and as high as 45 • . Laskar et al [1] estimate that there is a 63 per cent probability that the obliquity reached 60 • in the last 1 Gyr. At high obliquities when the summer pole faces the Sun, water ice sublimes from the poles and precipitates out at lower latitudes.…”

Section: Present Climatic Conditionsmentioning

confidence: 99%

The fluvial history of Mars

Carr

2012

Phil. Trans. R. Soc. A.

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River channels and valleys have been observed on several planetary bodies in addition to the Earth. Long sinuous valleys on Venus, our Moon and Jupiter's moon Io are clearly formed by lava, and branching valleys on Saturn's moon Titan may be forming today by rivers of methane. But by far the most dissected body in our Solar System apart from the Earth is Mars. Branching valleys that in plan resemble terrestrial river valleys are common throughout the most ancient landscapes preserved on the planet. Accompanying the valleys are the remains of other indicators of erosion and deposition, such as deltas, alluvial fans and lake beds. There is little reason to doubt that water was the erosive agent and that early in Mars' history, climatic conditions were very different from the present cold conditions and such that, at least episodically, water could flow across the surface. In addition to the branching valley networks, there are large flood features, termed outflow channels. These are similar to, but dwarf, the largest terrestrial flood channels. The consensus is that these channels were also cut by water although there are other possibilities. The outflow channels mostly postdate the valley networks, although most are still very ancient. They appear to have formed at a time when surface conditions were similar to those that prevail today. There is evidence that glacial activity has modified some of the water-worn valleys, particularly in the 30-50 • latitude belts, and ice may also be implicated in the formation of geologically recent, seemingly water-worn gullies on steep slopes. Mars also has had a long volcanic history, and long, sinuous lava channels similar to those on the Moon and Venus are common on and around the large volcanoes. These will not, however, be discussed further; the emphasis here is on the effects of running water on the evolution of the surface.

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Long term evolution and chaotic diffusion of the insolation quantities of Mars

Cited by 853 publications

References 68 publications

Transverse Aeolian Ridges (TARs) on Mars

Transverse Aeolian Ridges (TARs) on Mars

Cracks in Martian boulders exhibit preferred orientations that point to solar-induced thermal stress

The fluvial history of Mars

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