The geology of the Viking Lander 2 site revisited

Thomson, Bradley J.; Schultz, P. H.

doi:10.1016/j.icarus.2007.05.011

Cited by 22 publications

(9 citation statements)

References 86 publications

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“…The last hypothesis is that cemented ferricrete blocks beneath the surface were concentrated into lag deposits by deflation. The formation of lag deposits requires dozens of meters of deflation of concentrated rocks and boulders on the surface, and the VL2 landscape is deflated by more than 100 m to fulfill the requirements reported by Thomson and Schultz (2007). However, our erosion rate estimations do not support this resurfacing process, although the erosion rates are significantly higher in northern Utopia Planitia than those in the southern region.…”

Section: Discussionmentioning

confidence: 98%

Rock Abundance and Erosion Rate at the Zhurong Landing Site in Southern Utopia Planitia on Mars

Chen

Liu

et al. 2022

Earth and Space Science

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Rocks on the Martian surface exhibit signatures of geological activities. Rock distribution is also an important factor for landing site selection for exploration missions. This study investigated the rock abundance and erosion rate at the landing site of the Chinese Mars rover, Zhurong, in southern Utopia Planitia. A convolutional neural network based method was developed for rock detection from the images (0.7 m/pixel) obtained by using the high‐resolution imaging camera (HiRIC) onboard the Tianwen‐1 orbiter. Approximately 10,000 rocks with a minimum diameter of 1.4 m (2 pixels on the image) were extracted from the HiRIC images covering the Zhurong landing site and its neighboring region. According to the results, the rock abundance at the Zhurong landing site was approximately 5%. Measurements from the ground images acquired by the Zhurong rover after landing confirmed a rock abundance of approximately 5% at the landing site, consistent with the orbital measurement before landing. Furthermore, we investigated the rock erosion rate at the Zhurong landing region. Rock abundance was negatively correlated with the crater retention age and positively correlated with crater diameter. The obtained rock breakdown rate (0.054 nm/y to 0.074 nm/y) and surface denudation rate by filled volume of craters (0.104 nm/y to 0.209 nm/y) were in agreement with the values previously reported for the Amazonian period on Mars. The low erosion rate implies a dry climate and the absence of fluvial erosion processes in the Amazonian period.

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Section: Discussionmentioning

confidence: 98%

Rock Abundance and Erosion Rate at the Zhurong Landing Site in Southern Utopia Planitia on Mars

Chen

Liu

et al. 2022

Earth and Space Science

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“…First, both Viking I Lander and Pathfinder sites in Chryse Planitia are in a region that underwent significant resurfacing by Hesperian floods related to the outflow channels [ Mutch et al , 1977; Golombek and Bridges , 2000], which would have reduced the prolonged contributions of distal impact melts. Second, the Viking II Landing site occurs at latitudes where cyclic expansion polar deposits have resurfaced the region resulting in numerous pedestal craters of different ages and leaving behind mantling deposits [ Thomson and Schultz , 2007]. Third, the two Mars Rovers landed in regions covered by mantling deposits on the opposite sides of the planet.…”

Section: Discussionmentioning

confidence: 99%

The oblique impact Hale and its consequences on Mars

Schultz

Wrobel

2012

J. Geophys. Res.

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1] Highly oblique impacts represent a rare and special class of impact events manifested as elliptical craters preserved on present-day planetary surfaces. Crater excavation in highly oblique impacts differs from that of standard vertical impacts due to early time asymmetries imparted by the downrange-directed coupling of energy between the projectile and target. Such asymmetries are preserved as scouring and mobilized surface materials produced by high-velocity, low-angle ejecta and blast winds along the initial impact trajectory axis downrange. Subsequent deposition of resulting melt-rich products occurs in the form of concentrated strewnfields located downrange from the impact. The distinct nature of these distal strewnfields is separate from later time, more proximal ejecta accumulations and generally allows connecting these specific deposits with their parent crater. The present study involves a three-dimensional computational impact simulation (modeled using the CTH shock physics hydrocode) of an event similar to the impact that produced the elliptical Hale impact crater on Mars (125 km Â 150 km diameter crater located at 36 S, 36 W). Results generally capture the predicted patterns indicative of highly oblique impacts. Evidence is presented for correlated distal strewnfields located downrange from Hale that coincide with prominent low-albedo surface deposits and wind streaks on the present-day Martian surface, thereby providing implications for possible identification for other dark glassy strewnfields as well as impact-generated winds on Mars.

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“…These glaciers should already be visible at the resolution of the MRO imagery but nothing was ever seen so far. Observations have instead shown that water and dry ice sublimate between night and day in the cold weather of Mars at equatorial latitudes (Thomas and Schimel, 1991;Thomson and Schultz, 2007). The observations at the Phoenix landing site have shown how ice sublimated in about four sols even at higher latitudes (around 66°North) than Mangala Valles when brought to the surface from the shallow underground (Smith et al, 2009).…”

Section: Glacial Erosionmentioning

confidence: 99%

Mangala Valles, Mars: A reassessment of formation processes based on a new geomorphological and stratigraphic analysis of the geological units

Leone¹

2017

Journal of Volcanology and Geothermal Research

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Mangala Valles has always been viewed as the typical outflow channel formed by catastrophic floods of water. A new analysis has shown that the geomorphological traces of fluvial or lacustrine processes within Mangala Valles can be better explained by fluid lava flooding the channels and filling pre-existing impact craters. As for the circum-Chryse outflow channels, where no clear source of water or mechanism able to replenish water at its hydraulic head is observed, there is no geologic trace of a sudden removal of a volume of water (ice) necessary to carve Mangala Valles. Neither maars nor rootless cones, typical volcanic features indicative of interaction between lava and ground ice, were found. Past works suggested that the formation of Mangala Valles occurred in late Amazonian age when the climate of Mars was similar to that seen today, that is absolutely not liquid water friendly. The present work shows how the origin of Mangala Valles may go back to Noachian or even Pre-Noachian when other studies have concluded that the climate was not liquid water friendly. Even assuming limited periods of obliquity favourable to liquid water in the history of Mars, which is at odds with the widespread presence of unaltered olivine and jarosite, it is very difficult to find plausible mechanisms of aquifer recharge or signs of catastrophic water release at the Notch of Mangala Valles that could feed the multiple episodes, or even a single episode, of fluvial flooding suggested in the literature. This evidence and other analysis will show that the presence of water and, eventually, ground ice is not incontrovertible in the equatorial regions and should not be given for granted as commonly done so far in the literature. The geomorphological analysis of the Mars Reconnaissance Orbiter (MRO) images provided in this paper, combined with THEMIS and MOLA data, show how Mangala Fossa, from which Mangala Valles originated as a breakout, is an erosional channel formed by the flow of lava in a original tube coming from Daedalia Planum rather than a tectonic graben or the sign of a dike rupturing to the surface.

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The geology of the Viking Lander 2 site revisited

Cited by 22 publications

References 86 publications

Rock Abundance and Erosion Rate at the Zhurong Landing Site in Southern Utopia Planitia on Mars

Rock Abundance and Erosion Rate at the Zhurong Landing Site in Southern Utopia Planitia on Mars

The oblique impact Hale and its consequences on Mars

Mangala Valles, Mars: A reassessment of formation processes based on a new geomorphological and stratigraphic analysis of the geological units

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