[meteorite-list] Hadley Crater Provides Deep Insight Into Martian Geology (Mars Express)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 6 Sep 2012 09:46:46 -0700 (PDT)
Message-ID: <201209061646.q86GkknA022277_at_zagami.jpl.nasa.gov>


Hadley Crater provides deep insight into martian geology
European Space Agency
6 September 2012

Recently engaged in providing support to the successful landing of
NASA's Mars Science Laboratory's Curiosity rover, ESA's Mars Express has
now returned to its primary mission of studying the diverse geology and
atmosphere of the 'Red Planet' from orbit.
Earlier this year, the spacecraft observed the 120 km wide Hadley
Crater, providing a tantalising insight into the martian crust. The
images show multiple subsequent impacts within the main crater wall,
reaching depths of up to 2600 m below the surrounding surface.
Hadley Crater perspective view
This region imaged on 9 April 2012 by the High Resolution Stereo Camera
on Mars Express shows the crater which lies to the west of the Al-Qahira
Vallis in the transition zone between the old southern highlands and the
younger northern lowlands.

Hadley is named after the British lawyer and meteorologist George Hadley
(1685-1768) whose name was also given to the "Hadley cell", a
circulation system in the Earth's atmosphere, which transports heat and
moisture from the tropics up to higher latitudes.

The images show that Hadley Crater was struck multiple times by large
asteroids and/or comets after its initial formation and subsequent
infilling with lava and sediments.

Some of these later impacts have also been partly buried, with subtle
hints of a number of crater rims to the west (top), and wrinkle ridges
to the north (right side) of the main crater floor as shown in the first
image at the top of the page.
Hadley Crater in context
Again, in the first image (top of the page), the southern (left) side,
the crater appears shallower than the opposite side. This difference can
be explained by an erosion process known as mass wasting. This is where
surface material moves down a slope under the force of gravity.

Mass wasting can be initially started by a range of processes including
earthquakes, erosion at the base of the slope, ice splitting the rocks
or water being introduced into the slope material, In this case there is
no clear indication which process caused it, or over what timescales
this may have occurred.
Hadley Crater perspective view
Of particular interest to scientists studying the geology of Mars are
the ejecta of the smaller craters within Hadley. Two of them, one to the
west (top), and the deepest one in the middle of the first image, show
evidence for volatiles, possibly water ice beneath the surface.

With the impact that forms the craters, this ice would mix with
surrounding materials to form a kind of 'mud', which would then spread
over the surface as ejecta.
Topographical view of Hadley crater
Scientists believe these volatiles which were excavated by the impacts,
may indicate the presence of ice to a depth of around hundreds of
metres, this being the difference in depth between the surface and the
depths of the two craters.

This deep view into the martian crust within the walls of Hadley Crater
provides scientists an insight into the history of Mars. A history which
rovers like those currently on the Red Planet and others which follow
will doubtless continue to investigate.
3D anaglyph view of Hadley crater
Received on Thu 06 Sep 2012 12:46:46 PM PDT

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