An experiment conducted outside the International Space Station leads to a controversial theory about how life might 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. 

Deinococcus radiodurans is an extremophilic bacterium and one of the most radiation-resistant organisms known. It can survive cold, dehydration, vacuum, and acid, and therefore, is known as a polyextremophile and it has been listed as the world's toughest known bacterium in The Guinness Book Of World Records.

The results indicated the importance of the aggregated form of cells for surviving in harsh space environment. We also analyzed the samples exposed to space from 1 to 3 years. The experimental design enabled us to get and to extrapolate the survival time course and to predict the survival time of D. radiodurans. The results supported the concept of the massapanspermia if other requirements are met, such as ejection from the donor planet, transfer, and landing.

Source:  Kawaguchi et al,. DNA Damage and Survival Time Course of Deinococcal Cell Pellets During 3 Years of Exposure to Outer Space. Front. Microbiol. 11:2050. doi: 10.3389/fmicb.2020.02050. smithsonianmag.com