Yuki Kimura
Asteroid Ryugu visited by JAXA’s Hayabusa 2 mission
Scientists at Imperial College London say organic material found in asteroid rocks collected during Japan’s Hayabusa 2 mission only proves that terrestrial microbes can thrive on extraterrestrial material, not that extraterrestrial life has finally landed.
For decades, astrobiologists have debated whether organic samples found in space rocks are evidence of extraterrestrial life or just contamination from indigenous life on Earth.
In a new, recently published in the magazine Meteoritics & Planetary Sciencea team of researchers from Imperial College London proved that a sample recently brought back from asteroid 162173 Ryugu by the Hayabusa 2 mission is not complete proof of the existence of ETs.
The Japanese Aerospace Exploration Agency, JAXA, emerged in 2003 from the merger of three previous entities. Its was launched on December 3, 2014, and intercepted the asteroid 162173 Ryugu on June 27, 2018.
For a year and a half, the probe examined and collected samples from the asteroid before ejecting the Sample Return Capsulewhich landed safely on Earth on December 5, 2020. Meanwhile, the Hayabusa 2 continued its mission asteroid observation.
JAXA targeted 162173 Ryugu in search of clues about the origin of life. Being a asteroide carbonáceopotentially contained minerals, ice and organic compounds that were among the most primitive in the universe.
In addition to providing information about the origins of planets, JAXA hoped that 162173 Ryugu would provide them with important information about the origin of water and life on Earth.
A Evidence of microbes on asteroid would have been revolutionaryto the extent that it would finally confirm the existence of simple life forms coming from space, but also because could provide crucial evidence for the controversial panspermia hypothesis, explains .
Panspermia
A is the theory according to which life exists elsewhere and potentially arrived on Earth through unintentional contamination or directed by extraterrestrial life forms.
Such an event can include everythingof a microorganism that hitches a ride on a meteoroid even aliens who intentionally introduce life on a planet, as portrayed in the Alien saga film.
The concept is broadly plausible, but most scientists are skeptical. The idea does not explain how life arose; simply changes the story of its origins.
The biologists never discovered direct evidence that point to a scenario in which life did not arise on Earth.
A platform EXPOSE-R-2 of the European Space Agency (ESA) has demonstrated that some of Earth’s extremophiles, organisms that thrive in harsh environments, can survive in harsh space conditions, giving the idea some weight for proponents of panspermia.
Non-Ryugu Microbial Life
The Imperial College team was one of several groups to receive a piece of the precious 162173 Ryugu sample.
Those responsible for handling the sample meticulously followed strict transport and containment proceduresinvolving hermetically sealed containers and nitrogen storage.
At the National History Museum in London, scientists carried out X-ray analysis of the samples and other analyzes with an electron microscope.
When studying this exam, scientists found something extraordinary: filaments and rods that suggest the presence of microbial life.
“When we first looked at the sample, we were excited to see that there were small rods and filaments of organic matter present on the surface,” he explains. Matthew Gengeresearcher at ICL and main author of the study, at one of the institution.,
“They were tiny structures, about a millionth of a meter wide – like microbes!“, highlights the researcher.
Over the course of the study, microscopic life forms began to spread and take care of the rock for 19 days, until the population was gone to decrease.
This peak, followed by an overexpansion and a decline, indicated that scientists had observed a terrestrial organism colonizing the material organic matter in an extraterrestrial rock, rather than a dormant organism coming back to life.
Due to complications with the small number of bacteria in the rock and the procedures the sample underwent to protect it, the team did not attempt to remove any organisms for direct study.
Already lack of identification of the microorganism’s DNAthe team’s best hypothesis was that it was a variety of Bacillusvery common on Earth and known for aggressively colonizing new environments.
After repollution with ethanediol, the team did not detect any more filaments in the sample. Ultimately, observation showed the vulnerabilities of confinement procedures, rather than providing evidence of panspermia.
“These findings suggest that what we found were terrestrial microbes who found a new home in an extraterrestrial rock full of organic materials they could make use of. Ryugu was literally a ‘snack from space’ for microbes on Earth,” concluded Genge.
