Blue Like Mars
This image shows the west-facing side of an
impact crater in the mid-latitudes of Mars' northern hemisphere. Like
many mid-latitude Martian craters, this one has gullies along its walls
that are composed of alcoves, channels and debris aprons. The origins of
these gullies have been the subject of much debate; they could have
been formed by flowing water, liquid carbon dioxide or dry granular
flows.
Many of the other features observed in and around this
crater are indicative of an ice-rich terrain, which may lend credence to
the water formation hypothesis for these gullies. The most notable of
these features is scalloped terrain in and around the crater. This type
of terrain has been interpreted as a sign of surface caving, perhaps due
to sublimation of underlying ice. Sublimation is the process of a solid
changing directly to a gas.
Another sign of ice is the presence
of parallel lines and pitted material on the crater floor. Parallel
linear cracks are also observed along the crater wall over the gullies,
which could be due to thermal contraction of ice-rich material.
together, these features are evidence for ice-rich material having been
deposited in this region during different climatic conditions, material
that has subsequently begun to melt and/or sublimate under current
conditions. More recently, wind-blown deposits have accumulated around
the crater, as evidenced by the parallel ridges dominating the
landscape.
The High Resolution Imaging Science Experiment
(HiRISE) camera on NASA's Mars Reconnaissance Orbiter took the image on
April 13, 2010.
Image Credit: NASA/JPL-Caltech/University of
Arizona