Bacteria of the genus Deinococcus have officially survived three years in the vacuum of space. In theory, according to the researchers, they could therefore survive a trip between Earth and Mars.
The "panspermia" theory supports the possibility that microbes can migrate between planets and distribute life in the universe through meteorites or comets. Some are even convinced that life on Earth may have been delivered from space. Taking advantage of a favorable environment, these microbes could thus have evolved quietly.
This controversial idea of panspermia implies that microorganisms can survive a (very) long interplanetary journey, resisting temperature fluctuations and space radiation , among other threats.
A few years ago, researchers discovered bacteria of the genus Deinococcus floating twelve kilometers above the Earth . Nevertheless, while these organisms, known to form large colonies, seem resistant to UV rays, could they survive long enough in space to support interplanetary travel?
To find out, in 2015 Dr. Yamagishi and his team, from the University of Tokyo, placed dried aggregates of these bacteria in small pellets exposed to the outside of the International Space Station (ISS). These samples of different thicknesses were exposed to the space environment for three years. Details of this work were published a few days ago in Frontiers in Microbiology .
At the end of the study, the researchers found that all aggregates larger than 0.5 mm partially survived. Specifically, none of the bacteria placed on the surface had held up. On the other hand, the latter have created a protective layer allowing the survival of the rest of the colony located below.
Based on this data, the researchers estimate that these aggregates could have survived about fifteen years on the ISS . They also predict that a colony 1 mm in diameter could potentially survive up to eight years in the interplanetary vacuum. If so, that means a bacterial colony could theoretically survive a trip to Mars…or vice versa.
Previous experiments have already suggested that bacteria can survive in space by being protected by a rocky celestial body. This new study, on the other hand, is the first to raise the possibility that certain bacteria can survive in space in the form of aggregates. This is a concept that the authors called "massapanspermia".
Further research will obviously be needed before we can say for sure if panspermia is indeed possible. It is not known, for example, whether bacteria from space could survive a planetary landing.
However, if this is the case, then we could imagine that life could have been deposited on Earth before germinating. Conversely, like a dandelion, our planet could have breathed life into the vastness of space. And why not, maybe reach the red planet?
