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Martian mountain may answer big question

March 5, 2009
Courtesy Rice University
and World Science staff

The Mar­tian vol­ca­no Olym­pus Mons is about three times Mount Ever­est’s height. But it’s the small de­tails that ge­ol­o­gists Pat­rick Mc­Gov­ern and Jul­ia Mor­gan are look­ing at in think­ing about wheth­er the Red Plan­et ev­er had – or still sup­ports – life.

In sim­u­lat­ing the moun­tain’s forma­t­ion by com­put­er, Mc­Gov­ern and Mor­gan reached the con­clu­sion that an­cient wa­ter may still be trapped un­derneath. Their find­ings are pub­lished in Febru­ary’s is­sue of the re­search jour­nal Ge­ol­o­gy. 

Color indicates height in me­ters. (cour­tesy Rice U.)
The re­search­ers, at Rice Uni­ver­s­ity in Tex­as, found that only the pres­ence of an­cient clay sed­i­ments, im­ply­ing wa­ter, could ac­count for the vol­ca­no’s asym­met­ric shape.

Olym­pus stands al­most 15 miles (24 km) high but has a very shal­low slope. That slope hints at what lies be­neath, said the re­search­ers. They sus­pect if they were able to stand on the north­west side and start dig­ging, they’d even­tu­ally find clay sed­i­ment de­posited there bil­lions of years ago, be­fore the moun­tain was even a mole­hill.

The Eu­ro­pe­an Space Agen­cy’s Mars Ex­press space­craft has in re­cent years found abun­dant ev­i­dence of clay on Mars. This dove­tails with a pre­vi­ous the­o­ry that where Olym­pus Mons now stands, a lay­er of sed­i­ment once rested that may have been hun­dreds of me­ters (yards) thick.

Mor­gan and Mc­Gov­ern found in their com­put­er mod­els that vol­can­ic ma­te­ri­al was able to spread to Olym­pus-sized pro­por­tions be­cause of the clay’s friction-reducing ef­fect, a phe­nom­e­non al­so seen at vol­ca­noes in Ha­waii.

What may be trapped un­derneath is of great in­ter­est, said the re­search­ers. Flu­ids em­bed­ded in an impermea­ble, pres­su­rized clay sed­i­ment would al­low the kind of slip­ping mo­tion that would ac­count for Olym­pus Mons’ spread-out north­east flank – and they may still be there. Sci­en­tists al­ready know Mars has wa­ter thanks to NASA’s Phoe­nix lan­der, which scratched through the sur­face to find ice un­derneath the red dust last year.

The deep res­er­voir un­der Olym­pus Mons “would be a fa­vored en­vi­ron­ment” for heat-loving or­gan­isms, as a pro­tected ar­ea heat­ed partly by near­by vol­can­ic ac­ti­vity, Mor­gan and Mc­Gov­ern wrote. Find­ing the source of heat will be a chal­lenge, they ad­mit­ted, al­though a se­ries of seis­mic sta­t­ions on Mars might help by pick­ing up on ground move­ments.

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The Martian volcano Olympus Mons is about three times Mount Everest’s height. But it’s the small details that geologists Patrick McGovern and Julia Morgan are looking at in thinking about whether the Red Planet ever had – or still supports – life. In simulating the mountain’s formation by computer, McGovern and Morgan reached the conclusion that ancient water may still be trapped underneath. Their findings are published in February’s issue of the research journal Geology. The researchers, at Rice University in Texas, found that only the presence of ancient clay sediments, implying water, could account for the volcano’s asymmetric shape. Olympus stands almost 15 miles (24 km) high but has a very shallow slope. That slope hints at what lies beneath, said the researchers. They suspect if they were able to stand on the northwest side and start digging, they’d eventually find clay sediment deposited there billions of years ago, before the mountain was even a molehill. The European Space Agency’s Mars Express spacecraft has in recent years found abundant evidence of clay on Mars. This supports a previous theory that where Olympus Mons now stands, a layer of sediment once rested that may have been hundreds of meters (yards) thick. Morgan and McGovern found in their computer models that volcanic material was able to spread to Olympus-sized proportions because of the clay’s friction-reducing effect, a phenomenon also seen at volcanoes in Hawaii. What may be trapped underneath is of great interest, said the researchers. Fluids embedded in an impermeable, pressurized clay sediment would allow the kind of slipping motion that would account for Olympus Mons’ spread-out northeast flank – and they may still be there. Scientists already know Mars has water thanks to NASA’s Phoenix lander, which scratched through the surface to find ice underneath the red dust last year. The deep reservoir under Olympus Mons “would be a favored environment” for heat-loving organisms, as a protected area heated partly by nearby volcanic activity, Morgan and McGovern wrote. Finding the source of heat will be a challenge, they admitted, although a series of seismic stations on Mars might help by picking up on ground movements.