For life to exist, five informational units of DNA and RNA are required. These units are called nucleobases and are essential for every living thing to exist on Earth. Astrobiologists have been studying various meteorites (small chunks from asteroids that fall to Earth), and to date, they have only found three out of these five nucleobases, and were perplexed as to why. Guanine, adenine, and uracil have been found in meteorite samples before but the more elusive ones called cytosine and thymine were never found in these samples. Various research experiments showed that all five compounds can be synthesized in extraterrestrial environments, therefore, it was an open question why these two were missing.
An international team including researchers from NASA finally found these two missing compounds in the Murchison meteorite, which was found in Australia in 1969. The team suggests that the reason that these two were missing from previous data was due to the extraction technique. Both cytosine and thymine have delicate structures and during the synthesis process, which involves treating the meteorite sample in a hot bath of formic acid, which could potentially destroy these delicate units. This is done so that the molecules from the meteorite pass into the solution and then that solution is analyzed to check whether what components were there in the meteorite.
This team conducted their analysis in a slightly different way by using cool water for the extraction of the compounds. This is the reason that they found traces of more fragile compounds. These researchers report that even though this is an amazing discovery, and their findings are published in Nature Communications, it still is not enough to prove that a meteorite or an asteroid brought life to Earth. This discovery of finding the five compounds is a huge sign of progress toward understanding biology in space.
Source: Nature Communications, NASA Press Release
