[meteorite-list] Mars Express: The Pit-Chains of Mars - A Possible Place for Life?

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 10 Apr 2012 14:34:59 -0700 (PDT)
Message-ID: <201204102134.q3ALYxbx004442_at_zagami.jpl.nasa.gov>

http://www.esa.int/SPECIALS/Mars_Express/SEMK8FEWF0H_0.html

The pit-chains of Mars - a possible place for life?
European Space Agency
5 April 2012

The latest images released from ESA's Mars Express reveal a series of
"pit-chains" on the flanks of one of the largest volcanoes in the Solar
System. Depending on their origin, they might be tempting targets in the
search for microbial life on the Red Planet.
 
The images, taken on 22 June 2011, cover Tractus Catena in the Arcadia
quadrangle, part of the vast Tharsis region on Mars. This region boasts
a number of huge volcanoes, including the three collectively known as
Tharsis Montes. To their north sits Alba Mons, also known as Alba
Patera, one of the largest volcanoes in the Solar System by area and
volume.

Tractus Catena sits on its southeastern flank of Alba Mons and the
pit-chains in that region are a series of circular depressions that
formed along fracture points in the martian crust.

Pit-chains can have a volcanic origin. Lava streaming from a volcano
solidifies on the surface, leaving a molten tube of lava running below.
 
[Image]
Tractus Catena region

Once volcanic activity ceases, the tube empties, leaving behind a
subterranean cavity. Over time, parts of the roof over the cavity may
collapse, leaving circular depressions on the surface. On Earth, recent
examples can be seen on the flanks of Kilauea volcano in Hawaii, while
on the Moon, Hadley Rille, visited by Apollo 15 in 1971, is believed to
have formed in the same way billions of years ago.
 
 
[Image]
Pit-chains at high resolution
 
Pit-chains can also be caused by strains in the Martian crust, which
translates into a series of parallel elongated depressions known as
grabens, in which pits can also form.

But the most dramatic scenario involves groundwater. On Earth, there are
clear examples of similar structures in "Karst" regions - after the
German name for a region extending from Slovenia to Italy, where this
phenomenon was first studied.

Some of Earth's most famous examples are the network of "cenotes" on the
Yucatan peninsula of Mexico. These deep natural pits form when the
surface limestone rocks collapse, exposing the groundwater underneath.

This origin is the most interesting in the context of the search for
microbial life on Mars. If there are any cave-like structures associated
with the pits, microorganisms could have survived, protected from the
harsh surface environment.
 
 
[Image]
Map of the pit-chains
 
Mars landers have measured surface radiation around 250 times higher
than that found on the Earth, and more than double that experienced by
astronauts on board the International Space Station. Any caves
associated with the pit-chains may in future provide a possible refuge
for astronauts from the harsh surface radiation.

However they formed, these pit-chains show again just how similar many
of the geological processes on Mars are to those on the Earth, and
provide interesting targets for future missions.
 
 
[Image]
Tractus Catena pit-chains
 

[Image]
Pit-chains in 3D
 
 
Received on Tue 10 Apr 2012 05:34:59 PM PDT