Comment by johnsmalles
6 days ago
Fascinating that all five nucleobases were found in Ryugu samples. The fact that these formed abiotically in an asteroid environment strengthens the case that the building blocks of life are common throughout the solar system. The amino acid findings from the same samples were already compelling, but having the complete nucleobase set is a different level of evidence.
Ryugu showed an estimated ~20,000 different organic molecules. It's not that surprising that the nucleobases would be among them, along with all sorts of chemicals not relevant to life.
https://www.science.org/doi/10.1126/science.abn9033
In the reference from the link for this HN entry, we see the nucleobases were present at concentrations of about 1 nano-mole per gram (< 1 ppm). They are minor constituents present in a sea of mostly non-biologically relevant compounds.