sábado, 21 de abril de 2012

The pit-chains of Mars – a possible place for life?

The pit-chains of Mars – a possible place for life?
Pit-chains in Tharsis
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.
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.
A wider contextual image of the Tractus Catena region showing the surrounding fossae and the large shield volcano Ascraeus Mons, discovered by Mariner 9 in 1971. 
Credits: ESA/DLR/FU Berlin (G. Neukum)
Tractus Catena in monochrome from the nadir channel on the HRSC camera on Mars Express. The resolution in this image is 20 m/pixel. 
Credits: ESA/DLR/FU Berlin (G. Neukum) 
Tractus Catena in a colour-coded plan view based on a digital terrain model of the region, from which the topography of the landscape can be derived. 
Credits: ESA/DLR/FU Berlin (G. Neukum) 
Read more: ESA

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