Tuesday, May 27, 2014

Mars Arsia Mons volcano: Previously wet and habitable

Arsia Mons, the third-largest volcano on Mars may have been home to a habitable environment in Mars's relatively recent past. 

The rippled terrain in the foreground shows where a glacier once clung to the foothills of the mountain. 

Brown University researchers show that eruptions occurred under that ice sheet, which would have created lakes of liquid water. Where there was water, there's the possibility of past life. 

(Colours indicate elevation.) 

Credit: NASA /Goddard Space Flight Center /Arizona State University /Brown University

Heat from a volcano erupting beneath an immense glacier would have created large lakes of liquid water on Mars in the relatively recent past, and where there's water, there is also the possibility of life.

A recent paper by Brown University researchers calculates how much water may have been present near the Arsia Mons volcano and how long it may have remained.

The slopes of a giant Martian volcano, once covered in glacial ice, may have been home to one of the most recent habitable environments yet found on the Red Planet, according to new research led by Brown University geologists.

Nearly twice as tall as Mount EverestArsia Mons is the third tallest volcano on Mars and one of the largest mountains in the solar system.

This new analysis of the landforms surrounding Arsia Mons shows that eruptions along the volcano's northwest flank happened at the same time that a glacier covered the region around 210 million years ago.

The heat from those eruptions would have melted massive amounts of ice to form englacial lakes, bodies of water that form within glaciers like liquid bubbles in a half-frozen ice cube.

The ice-covered lakes of Arsia Mons would have held hundreds of cubic kilometers of meltwater, according to calculations by Kat Scanlon, a graduate student at Brown who led the work, and where there's water, there's the possibility of a habitable environment.

Kat Scanlon
"This is interesting because it's a way to get a lot of liquid water very recently on Mars," Scanlon said.

While 210 million years ago might not sound terribly recent, the Arsia Mons site is much younger than the habitable environments turned up by Curiosity and other Mars rovers.

Those sites are all likely older than 2.5 billion years. The fact that the Arsia Mons site is relatively young makes it an interesting target for possible future exploration.

"If signs of past life are ever found at those older sites, then Arsia Mons would be the next place I would want to go," Scanlon said.

A paper describing Scanlon's work is published in the journal Icarus.

Scientists have speculated since the 1970s that the northwest flank of Arsia Mons may once have been covered by glacial ice.

Jim Head
That view got a big boost in 2003 when Brown geologist Jim Head and David Marchant at Boston University, showed that terrain around Arsia Mons looks strikingly similar to landforms left by receding glaciers in the Dry Valleys of Antarctica.

Parallel ridges toward the bottom of the mountain appear to be drop moraines, piles of rubble deposited at the edges of a receding glacier.

An assemblage of small hills in the region also appears to be debris left behind by slowly flowing glacial ice.

The glacier idea got another boost with recently developed climate models for Mars that take into account changes in the planet's axis tilt.

The models suggested that during periods of increased tilt, ice now found at the poles would have migrated toward the equator.

That would make Mars's giant mid-latitude mountains; Ascraeus Mons, Pavonis Mons and Arsia Mons, prime locations for glaciation around 210 million years ago.

More information: Paper: www.sciencedirect.com

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