Meth­ane in Mars rocks could be a sign of life

Re­searchers are try­ing to de­ter­mine ori­gin of gas that is food source for mi­crobes on Earth.

Los Angeles Times - - OP-ED - By Amina Khan amina.khan@latimes.com Twit­ter: @am­i­nawrite

Sci­en­tists have dis­cov­ered meth­ane hid­den in Mar­tian me­te­orites, which could hint that the elu­sive gas, which on Earth is of­ten linked to life, might be lurk­ing be­neath the sur­face of Mars to­day.

The find­ings, pub­lished in the jour­nal Na­ture Com­mu­ni­ca­tions, could have im­pli­ca­tions for the bi­o­log­i­cal po­ten­tial of the Red Planet.

“The avail­abil­ity of meth­ane and hy­dro­gen is crit­i­cal to the po­ten­tial of the Mar­tian crust as a habi­tat for mi­cro­bial life,” the study au­thors wrote. “The hos­tile Mar­tian sur­face is prob­a­bly less hab­it­able than the sub­sur­face, and sev­eral sce­nar­ios have been pro­posed for deep Mar­tian life.”

The mys­tery of meth­ane on Mars has long dogged astro­bi­ol­o­gists look­ing to as­sess whether life could have ex­isted on the Red Planet.

Meth­ane can be made in non­bi­o­log­i­cal ways, but liv­ing things pro­duce the ma­jor­ity of meth­ane on Earth. The meth­ane on Mars could be a po­ten­tial food source for cer­tain types of micorbes that con­sume it.

But even as Mars in­creas­ingly looks like it had a life-friendly past, meth­ane on the Red Planet has proved re­mark­ably dif­fi­cult to pin down.

NASA’s Cu­rios­ity rover searched for months with­out luck, but later picked up what ap­peared to be in­ter­mit­tent plumes. Some sci­en­tists think the meth­ane read­ings might ac­tu­ally be con­tam­i­na­tion from the rover it­self, so the jury is still out on Mar­tian meth­ane for the mo­ment.

“The pu­ta­tive oc­cur­rence of meth­ane in the Mar­tian at­mos­phere has had a ma­jor in­flu­ence on the ex­plo­ration of Mars, es­pe­cially by the im­pli­ca­tion of ac­tive bi­ol­ogy,” the study au­thors wrote. “The oc­cur­rence has not been borne out by mea­sure­ments of at­mos­phere by the MSL rover Cu­rios­ity but, as on Earth, meth­ane on Mars is most likely in the sub­sur­face of the crust.”

For the study, an in­ter­na­tional team of re­searchers turned to data they could hold in their hands: six Mar­tian me­te­orites that have landed on Earth.

The re­searchers crushed rock from the me­te­orites, forc­ing out the gases trapped in­side. (Many ex­per­i­ments in­volve “cook­ing” rock to re­veal its con­tents, but that process of­ten ends up form­ing new mol­e­cules that can mud­dle the read­ings.)

“It’s an in­ter­est­ing, com­ple­men­tary way of get­ting in­for­ma­tion,” said Paul Ma­haffy, a plan­e­tary sci­en­tist at NASA’s God­dard Space Flight Cen­ter who was not in­volved in the study.

Among the re­leased gases, which in­cluded car­bon diox­ide, hy­dro­gen, ni­tro­gen and trace amounts of oxy­gen and ar­gon, the re­searchers found sig­nif­i­cant amounts of meth­ane and hy­dro­gen. The rel­a­tively high lev­els of these two very im­por­tant gases make sense, the au­thors said, given that the rocks were al­tered in the pres­ence of wa­ter.

Meth­ane is im­por­tant in the Earth’s “deep bio­sphere,” where meth­ane-eat­ing mi­crobes may use it as fod­der. If Mar­tian mi­crobes ever ex­isted, per­haps they played a sim­i­lar role on the Red Planet, the sci­en­tists said.

“The ev­i­dence pre­sented here in­di­cates that a meth­ane-bear­ing sub­sur­face habi­tat is sim­i­larly avail­able on Mars,” the au­thors wrote. “Whether or not the habi­tat has been oc­cu­pied re­mains to be de­ter­mined.”

But Ma­haffy warned that there were plenty of ways that meth­ane could have been brought to or pro­duced on Mars that have noth­ing to do with liv­ing things.

Very lit­tle is known about the amount of meth­ane, its ori­gins and its dy­nam­ics on the Red Planet, he said.

“I think that the whole meth­ane story to­gether, where it comes from and how of­ten it ap­pears in the at­mos­phere, is still not a solved prob­lem,” he said.

NASA

THE CU­RIOS­ITY ROVER has de­tected in­ter­mit­tent plumes of pos­si­ble meth­ane on the Red Planet.

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