Trying to understand the evolution of planets and life is really a driving motivation for a lot of science and science fiction. Landing squarely in the “I think I read a horror story about this,” scientists found that all attempts to prevent earth life from sneaking into a sample of material from the asteroid Ryugu were futile.
According to a paper led by Matthew Genge and appearing in Meteoritics & Planetary Science, “the sample was contaminated with microorganisms during the preparation of the polished block” prior to X-ray computed Tomography scans. They document that on October 14, 2022, the sample was removed from nitrogen and exposed briefly to the terrestrial atmosphere before being transferred to a sterilized pipette tip and stored within a sealed desiccator. It was then exposed again on November 3 and 4 after it was transferred to a mold and embedded in resin for polishing prior to storage in a sealed plastic container.
That brief exposure to air led to the subsequent growth and then die-off of micro-organisms that appeared to have a generation time of 5.2 days. While the life was initially happy to colonize the sample and grow, it was unable to survive the experiments and the sterile and thus food-free environment of the sample.
This experience makes it clear that it’s going to be really hard to know definitively if we ever find alien microbes on another world. Keeping things sterile is pretty much impossible and life will, as the saying goes, find a way.