They will. This is the conclusion reached by scientists studying bacterial aggregates. An aggregate is a large colony of unicellular organisms that form a multicellular and rather dense structure. If the aggregate is thick enough, then some bacteria will definitely survive the flight between two planets.
The research results were published in the Frontiers in Microbiology journal.
To measure the degree of resistance of bacterial clumps, the scientists used dehydrated samples of the Deinococcus strain. This bacteria is known for its radiation resistance. Then they were placed in special cases outside the ISS.
Deinococcus spent 1 to 3 years in open space. After that, the samples were brought back for analysis. Research has confirmed that there’re alive cells in all colonies more than 0.5 mm thick.
"This research shows that radio-resistant Deinococcus can make it through traverse from Earth to Mars and back," said in a press release of the lead researcher Akihiko Yamagishi, a professor at the Tokyo University. It should be added that such flights can take from several months to several years.
Of course, the biggest part of the aggregates died in unfavorable conditions. However, they also formed a defensive shield that blocked external factors' influence on other organisms. This discovery gives hope for the existence of alien life, even primitive.
One of the hypotheses made by the researchers is that life appearing on Earth is not a spontaneous coincidence, but a possible "infection" with bacteria, which in theory can migrate in a frozen state on one of the meteors. This phenomenon is called "panspermia"
Another important question scientists are struggling with is whether bacteria can survive with prolonged exposure to various negative factors. The main threats in space are, of course: lack of oxygen, high radiation, monstrous temperature fluctuations.
According to Yamagushi, the origin of life is still doubtable question in scientific society. There're two different parties: one think that our lifeforms are completely unique, while others argue and claim that life can be born on any planet with suitable conditions. There're much more inhabited places in the universe if it happens that panspermia is a real fact not just a theory.
To better assess the likelihood of panspermia, scientists must now study the bacteria's ability to survive the "start" and "landing" phases of interplanetary travel.