Is there re­ally life on Mars? We are closer to find­ing out

Weekend Herald - - World - Mar­cia Dunn

New Mars dis­cov­er­ies are ad­vanc­ing the case for pos­si­ble life on the red planet, past or even present.

Sci­en­tists re­ported yes­ter­day that Nasa’s Cu­rios­ity rover has found po­ten­tial build­ing blocks of life in an an­cient Mar­tian lakebed. Hints have been found be­fore, but this is the best ev­i­dence yet.

The or­ganic mol­e­cules pre­served in 3.5 bil­lion-year-old be­drock in Gale Crater sug­gest con­di­tions back then may have been con­ducive to life. That leaves open the pos­si­bil­ity that micro­organ­isms once pop­u­lated our plan­e­tary neigh­bour and might still ex­ist there.

“The chances of be­ing able to find signs of an­cient life with fu­ture mis­sions, if life ever was present, just went up,” said Cu­rios­ity’s project sci­en­tist, Ash­win Vasavada of Nasa’s Jet Propul­sion Lab­o­ra­tory in Pasadena, Cal­i­for­nia.

Cu­rios­ity also has con­firmed sharp sea­sonal in­creases of meth­ane in the Mar­tian at­mos­phere. Re­searchers said they can’t rule out a bi­o­log­i­cal source. Most of Earth’s at­mo­spheric meth­ane comes from an­i­mal and plant life, and the en­vi­ron­ment it­self.

The two stud­ies ap­pear in the jour­nal Science. In a com­pan­ion ar­ti­cle, an out­side ex­pert de­scribes the find­ings as “break­throughs in astro­bi­ol­ogy”. “The ques­tion of whether life might have orig­i­nated or ex­isted on Mars is a lot more op­por­tune now that we know that or­ganic mol­e­cules were present on its sur­face at the time,” wrote Utrecht Univer­sity as­tro­bi­ol­o­gist Inge Loes ten Kate of the Nether­lands.

Kirsten Siebach, a Rice Univer­sity ge­ol­o­gist who also was not in­volved in the stud­ies, is equally ex­cited. She said the dis­cov­er­ies break down some of the strong­est ar­gu­ments put for­ward by life-on-Mars scep­tics, her­self in­cluded.

“The big take­away is that we can find ev­i­dence. We can find or­ganic mat­ter pre­served in mud­stones that are more than 3 bil­lion years old,” Siebach said. “And we see re­leases of gas to­day that could be re­lated to life in the sub­sur­face or at the very least are prob­a­bly re­lated to warm wa­ter or en­vi­ron­ments where Earth life would be happy liv­ing.”

The meth­ane ob­ser­va­tions pro­vide “one of the most com­pelling” cases for present-day life, she said.

The big take­away is that we can find ev­i­dence. We can find or­ganic mat­ter pre­served in mud­stones. Kirsten Siebach

Sci­en­tists agree more pow­er­ful space­craft — and, ide­ally, rocks re­turned to Earth from Mars — are needed to prove whether tiny or­gan­isms like bac­te­ria ever ex­isted on the red planet.

Cu­rios­ity’s meth­ane mea­sure­ments oc­curred over four-and-a-half Earth years, cov­er­ing parts of three Mar­tian years. Sea­sonal peaks were de­tected in late sum­mer in the north­ern hemi­sphere and late win­ter in the south­ern hemi­sphere.

JPL’s Christo­pher Web­ster, lead au­thor on the study, said it’s the first time Mar­tian meth­ane has shown a re­peated pat­tern. The mag­ni­tude of these sea­sonal peaks — by a fac­tor of three — was far more than sci­en­tists ex­pected.

“We were just blown away,” he said. “It’s tripling . . . that’s a huge, huge dif­fer­ence.”

Web­ster the­o­rises that the meth­ane cre­ated ei­ther now or long ago is seep­ing from deep un­der­ground reser­voirs up through cracks and fis­sures in the crust.

Once at the sur­face, the meth­ane sticks to dirt and rocks, with more re­leased into the at­mos­phere when it’s hot­ter.

“We have no proof that the meth­ane is formed bi­o­log­i­cally, but we can­not rule it out, even with this new data set,” Web­ster said.

Sci­en­tists have been seek­ing or­ganic mol­e­cules on Mars ever since the 1976 Vik­ing lan­ders.

The twin Vik­ings came up pretty much empty.

Ar­riv­ing at Mars in 2012 with a drill and its own on­board labs, Cu­rios­ity con­firmed the pres­ence of or­gan­ics in rocks in 2013, but the mol­e­cules weren’t ex­actly what sci­en­tists ex­pected. So they looked else­where. The key sam­ples in the lat­est find­ings came from a spot 6.5km away.

As with meth­ane, there could well be non-bi­o­log­i­cal ex­pla­na­tions for the pres­ence of car­bon-con­tain­ing mol­e­cules on Mars, such as ge­o­logic pro­cesses or im­pacts by as­ter­oids, comet, me­te­ors and in­ter­plan­e­tary dust. Nasa has been try­ing to build in­ter­est with posters on fu­ture mis­sions to Mars.

Jen­nifer Ei­gen­brode, an as­tro­bi­ol­o­gist at Nasa’s God­dard Space Flight Cen­ter in Green­belt, Mary­land who led the or­gan­ics study, said she’s in­trigued by the pos­si­bil­ity that life might have ex­isted and adapted on Mars.

“I’m equally as fas­ci­nated by the idea that life never got started on Mars in the first place,” she said.

“That’s a harder ques­tion to ad­dress sci­en­tif­i­cally, but I think that we need to give the search for life on Mars due dili­gence.

“We need to go to places that we think are the most likely places to find it.” AP

Nasa’s Cu­rios­ity rover has found po­ten­tial build­ing blocks of life in an an­cient Mar­tian lakebed.

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