It may seem counterintuitive, but new research shows that observations taken from a great distance, even from orbit, may allow researchers to zoom in on martian microhabitats for the tiniest forms of life: microbes too small to see with the naked eye.
The new study, published March 6 in Nature, shows that imagery from a spacecraft orbiting Mars, possibly supplemented by aircraft data, could help scientists pinpoint the best places to search for microorganisms that might be present on the Red Planet today.
A team of scientists from NASA Ames Research Center, the SETI Institute, and other institutions carried out the detailed, years-long study in Chile’s Atacama Desert, which is considered to be one of the most Mars-like environments on Earth. The team found that a careful analysis of imagery obtained from Earth-orbiting satellites and drone aircraft could narrow down the viable search area by as much as 97 percent, which could help minimize the time astronauts or rovers on Mars spend searching unpromising locations.
This kind of targeted approach, the researchers say, could greatly improve the odds of finding biosignatures — evidence of past or present life — in future explorations of Mars or other terrestrial planets.
Is there life on Mars?
While many scientists think Mars is unlikely to currently harbor life, others point to results from the 1976 Viking landers that have been interpreted as possible evidence for microbes living at both the Viking lander sites.
The question remains unresolved. But the principal investigator for one of Viking’s life-detection tests, Gilbert Levin, maintained up until his death in 2021 that the evidence for life on Mars has only gotten stronger over the years, making it all the more important to do follow-up research in search of a definitive answer.
But where to look?
The new research was based on seeking life in a salt flat in the Atacama, where there is a variety of microbial life present. The team found that searching locations at random would produce evidence of life less than 10 percent of the time.
But using the new method they developed, which combines imagery and spectroscopy from satellites and drones that is then analyzed using machine deep learning, the researchers were able to predict search locations that yielded up to 87.5-percent success rates in finding life.
Life finds a way
How do Atacama microorganisms survive in such inhospitable conditions in the desert, where it sometimes doesn’t rain for years on end, and where intense ultraviolet radiation from the Sun tends to sterilize the surface?