[meteorite-list] Mars Express: Springtime at Mars' South Pole

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Wed, 8 Jun 2011 15:02:11 -0700 (PDT)
Message-ID: <201106082202.p58M2Bdx015110_at_zagami.jpl.nasa.gov>


Springtime at Mars' south pole
European Space Agency
7 June 2011

ESA's Mars Express celebrates eight years in space with a new view of
ice in the southern polar region of Mars. The poles are closely linked
to the planet's climate and constantly change with the seasons. Their
study is an important scientific objective of the mission.
Ulyxis Rupes in context

About two-thirds of the image is covered by part of the southern polar
ice cap and other scattered ice deposits, near a feature known as Ulyxis
Rupes. The left side of the image is dominated by the polar cap's ice
shield, which is covered by dark dusty material that hides the bright
ices beneath.

At this location, further than 1000 km from the south pole itself, the
ice is relatively thin: radar data indicate it is only about 500 m
thick, whereas near the south pole it can reach more than 3.7 km.
Features near Ulyxis Rupes

However, on the north-facing cliffs the layers of ice and dust are
discernible. These form part of the polar, layered deposits. The cliffs
are often curved, which could mean that they are shaped by underlying
impact craters.

The elevation of this region decreases markedly from south to north,
dropping in steps by about 1500 m in total from left to right across the
Elevation of Ulyxis Rupes

Just northward of the ice shield, about halfway across the image, there
are large ice deposits that are heavily covered by overlying material
blown into long dunes by the prevailing winds in this region. The
orientation of the dunes suggests the wind must come predominantly from
the northwest.
Ulyxis Rupes in high resolution
With increasing distance from the south pole, ice becomes confined to
larger impact craters, such as the one in the top right of the image.
These provide the best shelter. The ice itself is slightly offset
towards the north because, with the sunlight coming from the north, the
southern walls of the crater tend to warm up more, causing the ice to melt.

Ulyxis Rupes is a large cliff and is the only named feature in this
image ('rupes' is the Latin term for cliff). With a length of 390 km and
a height of up to 1 km, it is just visible at the top right of this
image where it intrudes on the immediate left of the crater there.
Ulyxis Rupes in perspective

Puzzling parallel structures in the martian dust can be seen in the
bottom right quarter of the image. Although their origin is uncertain,
it is possible that they are the result of underlying ice deposits,
permanently frozen because they are protected by overlying dust and rocks.

The image was taken in January 2011, during the southern spring on Mars.
At the moment it is summer there, but when the southern winter begins in
March 2012, the temperatures will drop again and more ice will
accumulate. Mars Express will be waiting.
Ulyxis Rupes in 3D
Received on Wed 08 Jun 2011 06:02:11 PM PDT

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