British scientists from Imperial College London have discovered that soil samples taken from asteroid Ryugu did not escape contamination by terrestrial microbes after the pieces were delivered to the laboratory. Even strict quarantine could not prevent bacterial colonization of space rocks. The research was published in the scientific journal magazine Meteoritics and Planetary Science (MPS).
Experts analyzed a sample of A0180, a small (1×0.8 mm) particle collected from the asteroid Ryugu by the Japan Aerospace Exploration Agency (JAXA) Hayabusa 2 mission.
The sample was delivered to Earth in a closed room. The container was opened in a nitrogen environment in a room with cleanliness class ISO 4 (no more than 10 thousand particles on a scale of 0.1 micrometers per cubic meter of air) to prevent contamination.
Before analysis, the sample underwent nano-X-ray computed tomography and was embedded in epoxy resin for scanning electron microscopy.
Despite all precautions, rods and filaments consisting of organic matter, defined as microorganisms, were found on the surface of the particle.
Observations showed that these microbes originated from terrestrial contamination during sample preparation, rather than coming from space on an asteroid.
According to the scientists, the results of the study provide evidence in favor of the panspermia hypothesis, which proposes that microorganisms are theoretically capable of traveling between worlds on comets and asteroids, based on the harsh environment of space.
Both the Moon and Mars were colonized by terrestrial microbes that likely arrived there via Earth-based vehicles, the researchers added.
Previous scientists assumedThe first missions to look for bacteria on Mars may have destroyed the microorganisms they were looking for because the methods used to analyze the samples were flawed.