SMITHSONIAN
An experiment conducted outside the International Space Station leads to a controversial theory about how life might travel between planets
Framed by an infinite backdrop of dark, lifeless space, a robotic arm on the International Space Station in 2015 mounted a box of exposed microbes on a handrail 250 miles above Earth. The hearty bacteria had no protection from an onslaught of cosmic ultraviolet, gamma, and x-rays. Back on Earth, scientists wondered whether the germs might survive these conditions for up to three years, the length of the experiment, and if they did, what the results might tell the researchers about the ability of life to travel between planets.
Microbiologists have spent decades studying extremophiles, organisms that endure extreme conditions, to tug at the mysterious threads of how life blossomed on Earth. Some extremophiles can live unprotected in space for several days; others can endure for years, but only by carving out a home inside rocks. These findings underpin the theory that life as we know it can transfer between planets within meteorites or comets. Now, new findings published today in Frontiers in Microbiology, based on that experiment on the International Space Station, show that the bacteria Deinococcus radiodurans can survive at least three years in space. Akihiko Yamagishi, a microbiologist at Tokyo University of Pharmacy and Life Sciences who led the study, says the results also suggest that microbial life could travel between planets unprotected by rock.
Max G. Levy 