New Delhi, India

The examination of a sample brought from asteroid Ryugu in outer space turned exciting for scientists when they found it had life forms on it. However, soon the excitement died down when they found that the microbes on the sample had actually originated on Earth.

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The sample was brought to Earth in 2020 after being gathered in 2019 during Japan’s Hayabusa2 mission.

Scientists treated the Ryugu samples with great care and kept them under strict contamination controls, limiting their chance of contamination.

However, researchers at Imperial College London still ended up finding signs of terrestrial life in the samples.

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"We found micro-organisms in a sample returned from an asteroid. They appeared on the rock and spread with time before finally dying off," said team leader Matthew Genge of Imperial College London while speaking to Space.com.  

Also Read: Was 'mini-moon' asteroid once part of our Moon? NASA will try to find out when it returns

"The change in the number of micro-organisms confirmed these were living microbes. However, it also suggested they only recently colonised the specimen just before our analyses and were terrestrial in origin," he added.

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"Without studying their DNA, it is impossible to identify their exact type. "However, they were most likely bacteria such as Bacillus since these are very common filamentous micro-organisms, particularly in soil and rocks," explained the researcher.

"It was very surprising to find terrestrial microbes within the rock. We usually polish meteorite specimens, and microbes rarely appear on them. However, it only needs one microbial spore to cause colonisation," said Genge.

What does contamination of asteroid sample mean?

In a study titled 'Rapid colonisation of a space-returned Ryugu sample by terrestrial microorganisms', the researchers said that no sign of contamination was shown in the material, however, filaments of organic matter which looked like terrestrial microbes were found on the surface of the sample in a week after it was exposed to the atmosphere of Earth.

Also Read: 16th asteroid to be discovered by man can make everyone on Earth a billionaire

"It shows that microorganisms can readily metabolise and survive upon extraterrestrial materials. On Earth, there is abundant home-grown organic material available, but on planets such as Mars, extra-martian organic materials may support an ecosystem," said Genge said. 

"Our findings suggest that space missions could be contaminating space environments. It also shows that terrestrial microorganisms are adept at rapid colonisation," he added.

"The fact that terrestrial microbes are the Earth's best colonisers means we can never completely discount terrestrial contamination. Most of the time, contamination is not a problem as long as you know its source. The problem comes when scientists attempt to claim that the 'pristine' nature of a specimen is evidence that features are extraterrestrial," the researcher further stated.

(With inputs from agencies)