Science & Technology

Arctic environments could yield clues about life on other planets

A research team led by Professor Lyle Whyte and post-doctoral fellow Jacqueline Goordial from McGill’s Department of Natural Resource Sciences has explored using low-cost, low-mass, and currently-available microbiological instruments to detect signs of life in astrobiological missions on other planets.

Published in the December 2017 issue of Frontiers in Microbiology, Whyte and Goordial’s study employed various devices, such as the MinION nucleic acid sequencer, to test for compounds that characterize life—specifically DNA and RNA—in one of Earth’s harshest climates: The Canadian High Arctic. The region’s permafrost, as well as the nutrient-poor soil found in the Arctic, are representational of the harsh environments found on celestial bodies like Mars, Europa, or Enceladus.

Instruments designed to detect alien life need to be able to identify it in small quantities and in nutrient-poor environments. Technologies that can only detect life in rich soils, for example, would not be effective on a planet like Mars.

For this reason, testing samples from areas generally thought to be uninhabitable by most life forms–like the Canadian High Arctic in Whyte and Goordial’s study–is important for one day being able to detect alien life on nutrient-poor planets. The team extracted samples from Arctic polygonal terrain permafrost—a type of patterned landscape which, coincidentally, is also found on Mars.

“This type of permafrost collected [polygon terrain] has dips in it and where you have these dips, you have ice wedges underneath the ground,” Isabelle Raymond-Bouchard, a postdoctoral researcher in microbiology in Whyte’s lab, told The McGill Tribune.

Raymond-Bouchard further explained why DNA and RNA are the best channels for detecting life. In contrast to many other molecules that are associated with living organisms, nucleic acids are only found in life forms.

“The instruments [currently used] on the [space] rovers are able to detect some organic molecules and maybe some amino acids but these can be created through abiotic processes,” Raymond-Bouchard said. “Just because you have those, it doesn’t mean you have life. That’s why we’re interested in looking at DNA and RNA; they are unambiguous signs you have life.”

Currently, nucleic acid sequencing units are huge, making them difficult to transport into space. However, smaller instruments, such as the Oxford Nanopore MinION for nucleic acid detection and sequencing, already exist and are an excellent alternative.

“[The MinION nucleic acid sequencer] is smaller than your cellphone in volume and weight,” said Ianina Altshuler, one of the authors of the study and a PhD candidate in the Department of Natural Resource Sciences at McGill. “We’re trying to push the limits of this technology to see what it can do.”

The team’s end goal is to create a life-detection platform small enough for use in outer space.

“The idea is that we can integrate different components, including the MinION sequencer, together into this platform that would be light, not too large, have low energy requirements and would fit on a space rover,” Raymond-Bouchard said.

The components of such a platform—such as nucleic acid extractors, isolators, and sequencers—could be swapped on and off the rover depending on the requirements of the mission.

At the moment, the individual experimental instruments of a platform like this would have to be used separately, due to intermediary steps that require human attention such as the tagging of extracted RNA before it can enter a sequencing machine. An automated system requiring only the input of a sample by a rover has yet to be developed. Such a system would allow nucleic acids to be detected onsite, rather than requiring a lab for analysis, saving both time and money and potentially accelerating progress in the search for alien life.

The team plans to go back to the Canadian High Arctic to test more samples using other miniature devices. Collecting samples from even harsher climates on Earth, like Antarctica, are a potential next step.

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