HiRISE Updates (2015 Mar 04)

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HiRISE Updates (2015 Mar 04)

Post by bystander » Thu Mar 05, 2015 4:54 pm

HiRISE Science Team wrote:

Dunes in Western Medusae Fossae Formation (ESP_039240_1730) (HiClip)

The dark dunes in the western Medusae Fossae formation provide some evidence of having a local origin.

This image shows no large dunes, but many of the dark sand patches cover slopes up to discrete layers. It is possible that the sand is eroding out from those layers, but slopes can also act as sand traps.
HiRISE Science Team wrote:

A Possible Landing Site for the 2020 Mission: Jezero Crater (ESP_039348_1985) (HiClip)

It’s not only when trying to find a scientifically interesting place to land that the high-resolution images from HiRISE come in handy: it’s also to identify potential hazards within a landing ellipse.

This is one of the trickier aspects of selecting landing sites on Mars: a place to do good science but also where the risks of landing are low. Jezero Crater is an ancient crater where clay minerals have been detected, and with a delta deposit indicating that water was once flowing into a lake. Since clays form the in presence of water, this crater would be a very good candidate for a lander to explore and build on what we’ve learned from the Mars Science Laboratory. Could some form of ancient life have existed here and for how long?

This is a stereo pair with ESP_039203_1985.
HiRISE Science Team wrote:

Craters Near Nilokeras Scopulus (ESP_039432_2115) (HiClip)

This image shows two pits partially filled with lumpy material, probably trapped dust that blew in from the atmosphere.

The pits themselves resemble impact craters, but they are part of a chain of similar features aligned with nearby faults, so they could be collapse features instead. Note also the tracks left by rolling boulders at the bottom of the craters.

Nilokeras Scopulus is the name for the cliff, about 756 kilometers long, in the northern hemisphere of Mars where these craters are located. It was named based on an albedo (brightness) feature mapped by astronomer E. M. Antoniadi in 1930.

This caption is based on a science rationale from HiWish.
Colin Dundas wrote:

Sand Avalanches in Meroe Patera (ESP_039955_1875) (HiClip)

One of the major extended-mission objectives for HiRISE has been to re-image parts of the surface to look for changes. Such observations can tell us what processes are active today. This image was acquired as part of a series to look for sand movement in Meroe Patera, not far from the active sand dunes of Nili Patera.

Our image shows that sand dunes are missing downwind (to the left) of a crater near the center of the observation, because sand falls into the crater and is trapped. Zooming in on the sand-coated crater wall and comparing it with older images revealed a surprise: several major sand flows slumped down into the crater (towards the upper left), leaving small ridges (called “levees”) along their path and rounded piles of sand at the end.

What caused these slumps? Dry ice, which is thought to cause flows in some gullies and the North polar dunes, does not occur this close to the equator. There is no sign of recurring slope lineae, the leading candidates for liquid on the Martian surface. Instead, it is most likely that these were dry flows. They are far larger than the avalanches commonly seen on sand dunes, typified by the shorter light streaks visible in the lower left part of the “after” image, so they might have been triggered by a Mars-quake or an unusually strong wind.

Credit: NASA/JPL/University of Arizona

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