Atmospheric variations and meteorite production on Mars

Chappelow, J. E.; Sharpton, V. L.

doi:10.1016/j.icarus.2006.05.013

Cited by 12 publications

(23 citation statements)

References 18 publications

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“…In addition to the above formation scenarios, it is also possible that Block Island (specifically) is the result of an aerocapture event that may have occurred in the relatively recent past. This being said, the highly restrictive conditions under which aerocapture can come about suggest that it is an unlikely scenario for the origin of Block Island (Pierazzo & Melosh 2000; Chappelow & Sharpton 2006).…”

Section: Discussionmentioning

confidence: 99%

“…To order of magnitude the bulk density of chondritic (stony) meteorites is about half that of the iron meteorites, and accordingly the characteristic size limit beyond which hypersonic impacts are expected will be of the order of 0.7 m. On this basis, one would expect to find numerous chondritic meteorites on the surface of Mars (Chappelow & Sharpton 2006). Indeed, one can reasonably assume that the abundance of chondritic meteorites per unit area on Mars will, just as it does on Earth, greatly exceed that of the irons.…”

Section: Discussionmentioning

confidence: 99%

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The making of Martian meteorite Block Island

Beech¹,

Coulson²

2010

Monthly Notices of the Royal Astronomical Society

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An analysis of the circumstances leading to the placement of the large iron meteorite, unofficially named Block Island, on Mars is presented. We investigate the possibility that Block Island fell during the late Noachian period on Mars when its atmosphere was much denser (and hence much more massive) than at the present time. Indeed, we find that in order to produce a non‐crater‐forming, non‐fragmenting meteorite with the characteristics of Block Island, the surface pressure of the Martian atmosphere must have been at least one to two orders of magnitude larger than it is at the present epoch.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

The making of Martian meteorite Block Island

Beech¹,

Coulson²

2010

Monthly Notices of the Royal Astronomical Society

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“…As of yet there are no confirmed chondritic meteorites that have been found on Mars, although candidates have been proposed, based on weathering profiles . This low chondritic population could be related to survival of stony meteorites requiring shallow atmospheric entry (~10°-30°) and masses <100 kg (Chappelow and Sharpton, 2006). However, cratering records indicate that the surface of Mars receives 1.7 -2.8 times more meteoritic material than that of Earth (JeongAhn and Malhotra, 2015;Shoemaker, 1977).…”

Section: Practicality Of Finding Meteorites On Marsmentioning

confidence: 99%

Evaluation of meteorites as habitats for terrestrial microorganisms: Results from the Nullarbor Plain, Australia, a Mars analogue site

Tait

Wilson

Tomkins

et al. 2017

Geochimica et Cosmochimica Acta

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“…It entered the atmosphere with a mass of more than 60 kg, underwent significant ablation during atmospheric passage, and ricocheted across the surface upon impact. We conclude that Heat Shield Rock probably represents physical evidence that Mars once had a denser atmosphere.Citation: Chappelow, J. E., and V. L. Sharpton (2006), The event that produced heat shield rock and its implications for the Martian atmosphere, Geophys. Res.…”

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confidence: 99%

“…Citation: Chappelow, J. E., and V. L. Sharpton (2006), The event that produced heat shield rock and its implications for the Martian atmosphere, Geophys. Res.…”

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The event that produced heat shield rock and its implications for the Martian atmosphere

Chappelow

Sharpton

2006

Geophysical Research Letters

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[1] Methods developed in previous work were used to estimate the mass, trajectory, and atmospheric conditions that produced Heat Shield Rock, the iron meteorite discovered on Mars by the Opportunity rover in January, 2005. We find that Heat Shield Rock encountered Mars at high speed and shallow entry angle, probably at a time when the planet possessed a thicker atmosphere. It entered the atmosphere with a mass of more than 60 kg, underwent significant ablation during atmospheric passage, and ricocheted across the surface upon impact. We conclude that Heat Shield Rock probably represents physical evidence that Mars once had a denser atmosphere.Citation: Chappelow, J. E., and V. L. Sharpton (2006), The event that produced heat shield rock and its implications for the Martian atmosphere, Geophys. Res. Lett., 33, L19201, doi:10.1029 [2] The January, 2005, discovery of the iron meteorite ''Heat Shield Rock'' (hereafter: HSR) [Arvidson and Squyres, 2005;Bell, 2005;Christensen, 2005;Rodionov et al., 2005] in Terra Meridiani, Mars, led to speculation that the presence of such a large, dense object implies that Mars must have had a denser atmosphere when it arrived (e.g., http://www.space.com/missionlaunches/ mars_meteor_050119.html). If so, HSR amounts to physical evidence of a past, denser Martian atmosphere. It has also been suggested that HSR's unweathered appearance and its well-exposed position indicate that it may have arrived quite recently on Mars (e.g., http://www.space. com/missionlaunches/mars_meteor_050120.html), but also that the absence of a nearby impact feature contradicts this theory (e.g., http://www.space.com/missionlaunches/ mars_meteorites_050126.html). If recent, HSR may represent hard evidence that Mars has indeed experienced the large, recent, obliquity-coupled atmospheric density variations posited by several researchers [e.g., Ward, 1992;Bills, 1990;Nakamura and Tajika, 2003]. In this work we investigate these issues quantitatively.[3] Imagery of Heat Shield Rock implies that it has an average radius of $0.12 m [Arvidson and Squyres, 2005;Rodionov et al., 2005] and a mass of $50 kg. Its exterior is covered with features consistent with surface ablation during high speed passage through an atmosphere (i.e. regmaglypts), and none suggestive that it is a fragment of a larger object that broke up in the atmosphere or upon impact (e.g., planar and/or angular features; see Figure 1). While the possibility remains that HSR came from some parent body which broke apart very high in Mars's atmosphere (thus allowing time for ablation to re-work its surface), previous work [Chappelow and Sharpton, 2005] indicates that fragmentation of iron meteoroids, even in the lower Martian atmosphere, is exceedingly rare. Thus, for our purposes, HSR is assumed to be the result of a single incident iron meteoroid, at least 40 kg in mass, which was aerobraked (decelerated) by the Martian atmosphere into a soft-landing on the surface, without fragmentation or deformation either in the atmosphere or upon impact.[4] To inv...

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Atmospheric variations and meteorite production on Mars

Cited by 12 publications

References 18 publications

The making of Martian meteorite Block Island

The making of Martian meteorite Block Island

Evaluation of meteorites as habitats for terrestrial microorganisms: Results from the Nullarbor Plain, Australia, a Mars analogue site

The event that produced heat shield rock and its implications for the Martian atmosphere

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