If humans are there, you will also find microbes. It's just a fact of life - we contaminate everything we touch. Which means that, hundreds of miles above the Earth, there are trillions of bacteria predicted to live on the International Space Station.

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The ability to identify these microbes in the station is something NASA has been working on for some time. If we can sort these microbes into space, this could help diagnose astronaut diseases, study how microbes survive in microgravity, and even identify extraterrestrial life - if there is any floating around.

Now, thanks to the Genes in Space-3 project, NASA astronauts and biochemists did just that. They identified unknown microbes aboard the space station for the first time. But now that the technique has been put to work in space, there's no telling what the astronauts can find next.

Previously, the only way to identify microbes on the International Space Station was to send them back to Earth for testing. Microbes had been sequenced aboard the ISS, but these samples were prepared on Earth. There was no way to find something in space and to identify it genetically at once.

We do our best to sterilize space equipment here on Earth before launch, but even the most extreme techniques can only reduce the number of microbes to 300 per square meter.

Since microbes have demonstrated the ability to survive in the vacuum of space, and having been found living up outside the ISS, being able to identify quickly will help to rule out - or confirm whether they are terrestrial microbes or not. (So ​​far, all microbes found inside and outside the ISS have been of terrestrial origin).

Identifying microbes was a two-step process. First, NASA astronaut and biochemist Peggy Whitson had to collect samples and subject them to the Polymerase Chain Reaction (PCR), a technique that amplifies a DNA sample to create many copies of it.

The second step was the sequencing and identification of microbes.

To do this, Whitson used Petri dishes to collect samples from various surfaces around the space station. So she just let the samples grow a week before transferring them to small test tubes.

At once, they saw microorganisms appear. In that case, microbes were all common and known microbes seen where humans live and work (NASA did not specify exactly which species they were). [ ScienceAlert ]