Mi­crobes of Mars?

An­cient lake on mars could have teemed with mi­cro­bial life, nasa claims.

The Star Malaysia - Star2 - - SCIENCE - By IAN SAM­PLE

AN ENOR­MOUS crater near the north­ern plains of Mars once har­boured an an­cient lake that could have sup­ported mi­cro­bial life, Nasa sci­en­tists claim.

The fresh­wa­ter lake stood for more than one hun­dred thou­sand years at the base of Gale Crater, a 150km-wide for­ma­tion that was cre­ated when a me­teor punched into the red planet around 3.7 bil­lion years ago.

Tests on rock sam­ples by Nasa’s Cu­rios­ity rover re­vealed the pres­ence of fine clay min­er­als that formed in a stand­ing body of wa­ter, and coarse-grained sand­stones laid down by river flows that drained into the lake.

“The pres­ence of th­ese min­er­als tells us the wa­ter was likely to be fresh wa­ter, which means it’s much more con­ducive for mi­cro­bial life,” said San­jeev Gupta, a ge­ol­o­gist at Im­pe­rial Col­lege, Lon­don, and a mem­ber of the Cu­rios­ity sci­ence team.

“Th­ese rocks are sim­i­lar to those we would find if we walked along the Dorset or Devon coast­line,” he added.

The Nasa team is not sure how deep or wide the lake was, but sus­pect it was deep enough not to have dried out pe­ri­od­i­cally, as this would have left traces of crack marks in the rock sam­ples.

The US$2.5bil (RM8­bil) rover landed on Mars in Au­gust last year on a mis­sion to ex­plore whether or not the planet may once have been hab­it­able, though not to look for signs of an­cient life it­self.

Cu­rios­ity’s main ob­jec­tive is to trun­dle up nearby Mount Sharp, a 5km-high moun­tain that sits in the mid­dle of Gale Crater. Through mea­sure­ments of its ex­posed rock faces at dif­fer­ent al­ti­tudes, re­searchers hope to piece to­gether the ge­o­log­i­cal his­tory of the planet.

But Cu­rios­ity did not make for Mount Sharp im­me­di­ately.

Af­ter re­lay­ing de­tails of the Mar­tian soil near its land­ing site, the rover was steered to­wards a 5m-deep trough in the crater called Yel­lowknife Bay.

Here, the ro­botic sci­ence lab­o­ra­tory drilled into a rock for­ma­tion called Sheepbed mud­stone and ex­am­ined the pow­der with its in­stru­ments.

Through a com­bi­na­tion of X-ray dif­frac­tion ex­per­i­ments and anal­y­ses of gases given off when the pow­der was baked in an on­board oven, re­searchers iden­ti­fied so-called smec­tite clay min­er­als that formed in wa­ter and el­e­ments cru­cial for life, in­clud­ing carbon, hy­dro­gen, oxy­gen, sul­phur, ni­tro­gen and phos­pho­rus.

The chem­i­cal makeup of the min­er­als showed that they formed in wa­ter that was prob­a­bly nei­ther too acidic nor too al­ka­line for life to ex­ist.

Writ­ing in the jour­nal Sci­ence, re­searchers ex­plain that the con­di­tions in the lake were well suited to sup­port a type of mi­cro­bial life called chemolithoau­totrophs.

Th­ese or­gan­isms are found on Earth and can sur­vive by break­ing down rocks and min­er­als for en­ergy.

The lake may have per­sisted on Mars for tens of thou­sands of years, said John Grotzinger, project sci­en­tist on the Nasa mis­sion at Caltech in Pasadena.

Monica Grady, pro­fes­sor of plan­e­tary and space sciences at Open Univer­sity, said the im­ages of rocks and min­er­als beamed back from Mars by the Cu­rios­ity rover were “spec­tac­u­lar, beau­ti­ful and ab­so­lutely com­pelling”.

Grady said the find­ings were shift­ing sci­en­tists’ views on how life might have ex­isted on Mars.

“The life we know on Earth is largely based on pho­to­syn­the­sis. Grass pho­to­syn­the­sises, cows eat the grass, we eat the cows. We know there are other plat­forms for life, but they are mostly at the bot­tom of the ocean and in re­ally odd places.”

In­stead of re­ly­ing on the Sun’s en­ergy, life in the Mar­tian lake could have sur­vived on en­ergy lib­er­ated by chem­i­cal re­ac­tions.

“This is re­ally, for the first time, show­ing that ab­so­lutely all the in­gre­di­ents for life are there based on chem­istry, and that would be re­ac­tions be­tween sul­phur and iron.

“It says that there ab­so­lutely were en­vi­ron­ments on Mars where en­ergy from chem­i­cal re­ac­tions could have been har­vested to make nu­tri­ent path­ways work. It’s so beau­ti­fully laid out.”

Grady said that even though the Mar­tian lake may have been around for only tens of thou­sands of years, that may have been long enough for life to emerge there.

“We don’t re­ally know how long it took for life to get go­ing on Earth. We don’t know if it got go­ing once or lots of times.

“The more we know about how life de­vel­oped on Earth, the more we’re be­gin­ning to un­der­stand that it didn’t take very long at all. The fact the lake might have been rel­a­tively short lived, in terms of hun­dreds of thou­sands of years, doesn’t mean that life couldn’t have got go­ing there. “It doesn’t mean that at all.” Cu­rios­ity has found some ev­i­dence for car­bon­ate rocks on Mars. Grady said that she and many other sci­en­tists are keen to see the rover find some of th­ese and an­a­lyse them. The rocks form in the pres­ence of carbon diox­ide, which on Earth is a prod­uct of res­pi­ra­tion, and is im­por­tant for pho­to­syn­the­sis and the carbon cy­cle. – Guardian News & Me­dia

Waters of Mars: an il­lus­trated con­cept for the pos­si­ble ex­tent of an an­cient lake in­side Gale crater, con­firmed by ex­am­in­ing mud­stone in the crater’s yel­lowknife bay area. The area’s his­tory likely in­cluded the com­ing and go­ing of mul­ti­ple lakes of dif­fer­ent sizes as cli­mate con­di­tions evolved. — aFP Photo/ nasa/ JPL-caltech

Newspapers in English

Newspapers from Malaysia

© PressReader. All rights reserved.