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Things that spawned from Earth usually survive only on this planet, as evidenced by astronauts needing everything from a gravity simulator to a radiation-proof vest to avoid possible health issues from floating around in space too long, but not everything needs a spacesuit.
Deinococcus radiodurans is one of those life-forms (the other is possibly the tardigrades stranded on the Moon). New research has proven that when these bacteria multiply in aggregates, most of them can survive killer radiation in the vacuum of space. Does this mean that hypothetical alien life might be able to hitch a ride on an asteroid? Maybe. Extremophiles like Deinoccocus may be proof that panspermia, or the spreading of life among planets, could have been possible when the universe was still in its nascent phase and might still be billions of years later.
When Dr. Akihiko Yamagishi and his research team first searched for microbes in the atmosphere — some scientists believe that microbes may be able to survive even in the scorching and poisonous atmosphere of Venus — they discovered Deinococcus hanging out about 7 miles above Earth. They then knew they had to test how radioresistant the bacteria really was.
“Deinococcus radiodurans was first isolated from canned meat sterilized by gamma ray radiation,” Yamagishi, who led a study recently published in Frontiers in Microbiology, told SYFY WIRE. “Scientists have been working to answer the question of how D. radiodurans acquired resistance against space radiation, because there is no place with radiation strong enough to kill it on the Earth. The radiation-resistant mechanism is found to be related to desiccation resistance, and the former may be the byproduct of the latter.”
Panspermia has been debated for as long as people have been looking up to the cosmos and wondering about alien life. During the dawn of the universe, objects were constantly smashing into each other, spreading organic and inorganic compounds with their space dust. No one has yet been able to find proof of living or fossilized life-forms that are or were legit extraterrestrials.
“We know that all the living organisms on the Earth are derived from one organism, the last common ancestor,” said Yamigashi. “Accordingly, if the life was transported from another planet, say Mars, it happened before the last common ancestor about 4 billion years ago. The organism transported to Earth must have the resistance against space environments, the mechanism may be related to that of Deinococcus in that case.”
Whether life on Earth originated somewhere else, or if primordial Earth life was transported elsewhere by bodies in space banging around, remains unknown. Perseverance is equipped to scour Mars for life. However, Mars may or may not have collided with Earth when the solar system was still young. Space rocks that were or would be chunks of planets and moons were also crashing everywhere. The question is whether any living or fossilized microbes on Mars actually crawled out of the Red Planet or were carried over from Earth as the result of panspermia. If Deinococcus can survive so unnaturally well in space, does that mean it may have come from somewhere else? Yamagishi is skeptical.
“We currently have no idea how to find out if Deinococcus originated somewhere else than Earth. Because our Earth is full of organisms so adapted to the environment, it would be difficult for foreign organisms to compete with those present. Rather, I think there may be another form of life on Mars,” he said.
What we definitely do know about Deinococcus now is that aggregates of the bacteria thicker than half a millimeter could make it as far as Mars and possibly hang around long enough for a round trip. Aggregates on the ISS were exposed to brutal cosmic radiation for one, two and three years and examined for survival at each interval. Bacteria on the surface of the aggregate did perish, but they provided a protective shield for those under them to continue to thrive. They proved that they could have survived from 15 to 45 years on the ISS if left alone.
Because rock can be a shield for microbes in space, many theories of microbes traveling on asteroids and meteorites exist. This is the first time they have been shown to survive in aggregates. Would we be able to borrow from Deinococcus to protect astronauts on extended missions to the Moon, Mars and beyond?
“Deinococcus has various mechanisms to cope with harsh environment. We will be able to learn the mechanism and may be able to adopt these mechanisms for humans in space,” Yamagishi said.
Since tardigrades can also survive desiccation like Deinococcus and reanimate if exposed to water, does that mean there is hope for the ones on the moon if human astronauts can find them in the future? If somebody steps on one, at least we’ll know where it came from.