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.

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.