The Red Planet is enjoying a surge in popularity, thanks to the recent television series Mars, by director Ron Howard, based on the 2015 book How We’ll Live on Mars, by Stephen Petranek.
The deserts of Morocco acted as the fourth planet in the TV series, but for a team of scientists looking for better ways of identifying life in hostile environments, the high Arctic permafrost of northern Canada was deemed an ideal stand-in.
The aim of the study, published recently in Frontiers in Microbiology, was to demonstrate how existing, low-cost and lightweight technology can be used to search for life on distant planets.
“The search for life is a major focus of planetary exploration,” says Jacqueline Goordial, one of the study authors. “But there hasn’t been direct life-detection instrumentation on a mission since the 1970s, during the Viking missions to Mars. We wanted to show a proof-of-concept that microbial life can be directly detected and identified using very portable, low-weight, and low-energy tools.”
At present, most instruments on astrobiology missions look for habitable conditions, small organic molecules and other biological evidence that generally could not be formed without life being present. But these provide only indirect evidence.
Most of the available life-detecting tools are relatively large and heavy and consume lots of energy, rendering them unsuitable for missions to Europa and Enceladus – moons of Jupiter and Saturn – which, along with Mars, are the primary targets in the search for ET in our solar system.
Goordial, Lyle Whyte, and other scientists from Canada’s McGill University, took a different approach: they built a modular “life detection platform”, using existing equipment that was small, lightweight, low-cost, energy efficient and robust, with which they could culture microorganisms from soil samples, assess microbial activity, and sequence DNA and RNA.
With the aim being to search for life on Mars and other extremely cold environments, the platform would need to work in extreme temperatures.
“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,” Goordial says. “For this reason, we chose a site about 900 kilometres from the North Pole as a Mars analogue, to take samples and test our methods.”
Using an Oxford Nanopore MiniON, a commercially available, portable, miniature DNA sequencing device, the researchers demonstrated its use in examining environmental samples in extreme and remote settings, and also that it can be combined with other tools to detect active microbial life in the field. {%recommended 5026%}
The researchers were able to isolate microorganisms that thrive in extreme conditions, and which have never been cultured before, detect microbial activity, and sequence DNA from active microbes.
Whyte adds: “Successful detection of nucleic acids in Martian permafrost samples would provide unambiguous evidence of life on another world.”
“The presence of DNA alone doesn’t tell you much about the state of an organism, however – it could be dormant or dead, for example,” Goordial says. “By using the DNA sequencer with the other methodology in our platform, we were able to first find active life and then identify it and analyse its genomic potential, that is, the kinds of functional genes it has.”
Despite its success in the Canadian cold, the platform is not yet ready for a space mission.
“Humans were required to carry out much of the experimentation in this study, while life detection missions on other planets will need to be robotic,” Whyte explains. “The DNA sequencer also needs higher accuracy and durability to withstand the long timescales required for planetary missions.”
Nevertheless, Goordial and her team hope this study will act as a starting point for future development of life detection tools.
The platform has potential applications here on earth. “The types of analyses performed by our platform are typically carried out in the laboratory, after shipping samples back from the field, Goordial says. “We show that microbial ecology studies can now be done in real time, directly on site – including in extreme environments like the Arctic and Antarctic.”
This could be useful in remote and hard to sample areas, in cases where bringing samples back to the lab may change their composition, and for gaining information in real time, such as detecting and identifying pathogens during epidemics in remote areas, or when conditions are rapidly changing.
And one day it may indeed provide conclusive evidence for life beyond earth. “Several planetary bodies are thought to have habitable conditions, it’s an exciting time for astrobiology,” Goordial says.