Primitive plants are the latest forms of Earth life to show they can survive in the harshness of space, and for many months. Cold-loving algae from the Arctic Circle have joined the space-travelling club, alongside bacteria, lichens and even simple animals called tardigrades.
Preliminary studies of the algae after their return to Earth from the International Space Station lend some weight to the “panspermia” theory, that comets and meteorites could potentially deliver life to otherwise sterile planets. The results also provide insights into the potential for human colonies on distant planets to grow crops brought from Earth.
The algae were of the Sphaerocystis species, codenamed CCCryo 101-99, and were returned to Earth in June last year after spending 530 days on a panel outside the ISS. While space-borne, they withstood the vacuum, temperatures ranging from -20 °C at night to 47.2 °C during the day, plus perpetual ultraviolet radiation of a strength that would destroy most life on Earth if not filtered out by the atmosphere.
“I’m sure that plants of many kinds have been on the ISS before, but on the inside, not the outside,” says Thomas Leya of the Fraunhofer Institute for Cell Therapy and Immunology in Potsdam, Germany, who organised the algae experiment. “As far as I know, this is the first report of plants exposed on the surface of the space station.”
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