Find­ing DNA on Mars

In­stru­ments to de­tect life haven’t been sent on a plan­e­tary mission since the 1970s. Canadian re­searchers are work­ing on a so­lu­tion.

Cosmos - - Digest -

The Cu­rios­ity rover has been a star per­former. Its on­board science lab dis­cov­ered that Gale Crater, its land­ing site on Mars, was once a wa­ter-filled lake that could have sup­ported life. It drilled into the sand­stone rocks and de­tected or­ganic mol­e­cules, and it sniffed meth­ane in the at­mos­phere. All of which was tan­ta­lis­ing ev­i­dence that Mars might once have been in­hab­ited.

The fol­low-up act for the Mars 2020 Rover will be to hunt down more ev­i­dence of past life by sam­pling other promis­ing lo­ca­tions for biosig­na­tures.

Re­searchers based at Mcgill Univer­sity, Canada, are up­ping the ante. In a pa­per pub­lished in Fron­tiers in Mi­cro­bi­ol­ogy, they have pro­vided a proof of con­cept that fu­ture mis­sions could de­tect and read DNA se­quences – the de­fin­i­tive ev­i­dence of life.

The Mcgill sci­en­tists built a ‘life de­tec­tion plat­form’ that could fit on the back of a rover. The star player is the Ox­ford Nanopore Min­ion. Un­veiled to the world in 2016, it em­ployed new tech­nol­ogy that en­abled DNA se­quencers to shrink from ta­ble-sized to pocket-sized and run on the mea­gre power of a lap­top. The plat­form also con­tains kits to de­tect cell me­tab­o­lism and for cul­tur­ing cells.

The team showed the plat­form was suc­cess­fully able to de­tect the DNA of bac­te­ria and meta­bolic ac­tiv­ity dur­ing a mission to Axel Heiberg Is­land, about 900 km from the North Pole.

“Mars is a very cold and dry planet with a per­mafrost ter­rain that looks a lot like what we find in the Canadian high Arc­tic,” says co-author Jacqueline Go­or­dial.

There has been no di­rect life-de­tec­tion in­stru­men­ta­tion on a Mars mission since the 1970s, when the two Vik­ing lan­ders tested soil for ev­i­dence of mi­crobes, with in­con­sis­tent re­sults. While the Cu­rios­ity rover de­tected or­ganic mol­e­cules, they could have come from non-liv­ing sources.

Suc­cess­fully de­tect­ing DNA in Mar­tian per­mafrost would pro­vide “un­am­bigu­ous ev­i­dence of life”, says team mem­ber Lyle Whyte.

Alas, the plat­form is not yet ready for a space mission since hu­mans were needed to sam­ple ma­te­ri­als and feed them to the ma­chines. The team is hope­ful, though, the lab will first be used on other hunts for ex­treme life on Earth, and ul­ti­mately on other plan­ets.

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