Samples from the asteroid Ryugu brought back from space have been contaminated by terrestrial life!

Send the Hyabusa 2 probe from the Japanese agency Jaxa to orbit an asteroid 1000 km in diameter 440 million kilometers from Earth, hit it to extract material and bring it back to us, that's it a very rock'n'roll mission! But realizing once the analyzes have been carried out that this treasure collected in the depths of space thanks to our finest engineering is already contaminated by terrestrial biology is much less cool…

Ryugu is a potentially dangerous near-Earth spacecraft

The target, named Ryugu, is a so-called Apollo class C asteroid, whose orbit crosses that of our planet. It is compared to meteorites called carbonaceous chondritesvery primitive elements of the Solar System. The interest in studying them very closely is therefore immense. This is what this little space mountain looks like.

Hayabusa had been a success with more than 5.4 g of material taken from the asteroid instead of the 100 mg planned. This mission had also shown that contrary to what we thought, almost no dust from regolith is not found on the surface of Ryugu, unlike the Moon, probably because of the too weak gravity of such a star.

Thanks to international scientific collaboration, French researchers from the CRPG in Nancy and NASA therefore had access to portions of the material taken. And amazement when reading the results of the analysis of sample A0180: it was contaminated by terrestrial biology despite strict hygiene measures, namely transport in an airtight chamber, opening with nitrogen in the room white and sterilized tools. Life has therefore colonized this extraterrestrial matter at a surprising speed!

Of course, this presence of biological organisms does not render the Hyabusa mission on the origins of the Solar System obsolete, in particular the so-called petrochemical analyses, but it sheds light on several very interesting areas. Indeed, these organisms are prokaryotes with a generation time of 5.2 days. In summary, prokaryotes are among the simplest microorganisms existing on Earth, of the same type as the first to colonize the Earth 3.8 billion years ago.

Three lessons can be learned from this contamination:

• First, the panspermia hypothesis, which would suggest that life on Earth was brought by space material (meteorites, comets, etc.), takes a hit. This theory imagined 2000 years ago in ancient Greece, more or less supported by the discovery of micro-organisms on meteorites – therefore rocks that arrived on our soil – is now found without irrefutable proof. It is more than likely that these famous microorganisms were in fact terrestrial.

• Second, space agencies know this very well, but the likelihood that we ourselves will accidentally bring the life we ​​seek to other worlds is real. Mars, the Moon, possibly Titan…Who knows if the first Viking probes or the first Mars rovers did not spread terrestrial bacteria, despite all the pre-launch sterilization efforts?

• Third lesson advanced in the study which we echo here, in the form of evidence: the hygiene measures were not strict enough. The class of clean room used could accommodate 10,000 particles/m³, which is still too much. This is what a biologist working in the space field confirmed to us. According to him, the standard should be lowered to 100 to avoid such mishaps.

We can even add a fourth moral to this story: life on Earth is so abundant that all beings are linked by a common origin. No, living things do not need to start from scratch and we are therefore many kinds of bacteria that have “succeeded”. It is therefore appropriate to be more careful with the material that we strive to collect in space.