The Japanese spacecraft Hayabusa2 returned samples from the asteroid Ryugu to Earth back in 2020, and since then, teams of scientists worldwide have been meticulously analyzing their composition.
Research conducted last year indicated that the Ryugu samples contain life-essential molecules that are "older than the Solar System itself," while one of the latest analyses suggested that some of the elements likely originate directly from Earth.
Ryugu belongs to the most common category of asteroids (C-type or carbonaceous asteroids); 75% of all asteroids found in the Solar System are carbonaceous. Essentially, they are debris left over from the formation of the Solar System, making them quite intriguing for studying molecules that emerged nearly 4.5 billion years ago.
The sample analyzed in the latest study is part of a larger stone weighing 5.2 grams and was found to contain "filamentous" microorganisms very similar to terrestrial prokaryotic bacteria.
Scientists have long debated whether life on Earth originated directly on our planet or came "from the heavens." Previous analyses of meteorites found on Earth showed that some of these space rocks contained five nucleotide bases necessary for organic life—but the question of whether they were "contaminated" by these elements after landing on Earth remained unresolved. The Hayabusa2 mission was one of the first to attempt to find an answer.
Initially, scientists from the UK, upon receiving a sample from their Japanese colleagues, scanned the stone using X-rays and found no signs of bacteria on its surface. However, three weeks later, they made another attempt—encasing the sample in resin and using a scanning electron microscope, they finally observed threads of organic material on the surface.
The growth patterns, shapes, and sudden emergence of bacteria closely resembled those found on Earth—raising the question of contamination after landing on the planet once again. The conclusions presented in the paper highlight not only the importance of adhering to strict sample analysis protocols but also emphasize the remarkable adaptability of Earth bacteria, which can rapidly absorb organic material from anywhere, regardless of the planet.
"The presence of microorganisms in meteorites has been used as evidence of extraterrestrial life; however, the potential for Earth contamination makes their interpretation highly contentious," the researchers write. "The discovery underscores that terrestrial bioorganisms can quickly colonize extraterrestrial specimens, even when contamination control measures are in place."
The article was published in the journal Meteoritics and Planetary Science
Source: livescience
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