“The fact that terrestrial microbes are the best colonizers of Earth means we can never completely ignore terrestrial pollution.”

Scientists have discovered that a sample of the asteroid Ryugu delivered to our planet is teeming with terrestrial life forms. The study shows how successfully terrestrial microorganisms colonize even extraterrestrial materials.

The samples were collected by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 spacecraft, which launched in December 2014 and rendezvoused with Ryugu in June 2018. Haybusa2 then spent a year studying the asteroid, which is about 900 feet in diameter. meters) before diving to its surface and taking a sample.

This Ryugu sample was returned to Earth on December 6, 2020, but Haybusa2 continued to explore other asteroids. The sample was split and sent to different groups of scientists, including the group that made this new discovery.

“It appeared on the rock and spread over time before eventually dying,” team leader Matthew Genge of Imperial College London told Space.com. “The change in the number of microorganisms confirmed that these were living microbes. But it also suggested that they had just colonized the sample just before our analysis and were of terrestrial origin.”

The discovery took the form of rods and threads of organic matter, which the team interpreted as filamentous microorganisms. The team doesn’t know exactly what type of microorganism it is, but Genge has a good idea what it might be.

“It is impossible to determine their exact species without examining their DNA,” the researcher said. “But these were most likely bacteria such as Bacillus, because these are filamentous microorganisms that are very common, especially in soil and rocks.”

Of course, as humanity is now searching for microbial life beyond our planet, particularly on Mars, the question is: Could these microorganisms be present on Ryugu when the sample was collected and thus represent alien life?

Unfortunately, the team successfully and definitively eliminated this.

“We performed nano X-ray computed tomography before preparing the sample and no microbes were detected,” Genge said. “In any case, the population changes suggest that they only appeared after the rock entered the atmosphere, more than a year after it returned to Earth.”

Researchers found that within a week of the sample entering Earth’s atmosphere, 11 microbes were present on its surface. Just a week later the number of land colonists increased to 147 people.

“It was very surprising to find terrestrial microbes in the rock,” Genge said. “We often polish meteorite samples, and microbes rarely appear on them. But only one microbe spore is enough for colonization.”

While these results don’t tell us much about extraterrestrial life, they do tell us about the resilience of life forms on Earth, especially microorganisms. The resulting data also impacts the impact of spacecraft and rovers on the planets they visit.

“This shows that microorganisms can easily metabolize and survive.”
extraterrestrial materials. There is plenty of homegrown organic matter on Earth, but on planets like Mars, non-Martian organic matter can sustain an ecosystem,” Genge said. “Our findings suggest that spaceflight can pollute space. “This also shows that terrestrial microorganisms are capable of rapid colonization.”

Fortunately, Genge noted, space agencies are taking steps to protect the planet to minimize the possibility of contamination. Genge also warns that scientists need to be careful about contamination when future samples are returned to Earth before assuming extraterrestrial life has been discovered.

“The fact that terrestrial microbes are the best colonizers of Earth means that we can never completely ignore terrestrial pollution,” the researcher continued. “For the most part, pollution isn’t a problem as long as you know the source. “The problem arises when scientists try to claim that the ‘pristine’ nature of the sample is evidence that the features are extraterrestrial.”

The Imperial College London researcher and his team are looking forward to discovering new asteroid samples without visitors from Earth!

“The team continues to examine samples from Ryugu and Bennu. Hopefully terrestrial bacteria will not colonize these materials next time!” Genge concluded his words: The team’s research was published in the journal Meteoritics & Planetary Science.