NASA thinks that it has found evidence that the building blocks of life may have come from asteroids and comets that stuck the earth. According to researchers that were funded by NASA, some of the building blocks needed for DNA have been found in meteorites and were likely created in space. The building blocks found in the meteorites are adenine and guanine.
The new discovery adds to evidence that the chemistry inside an asteroid or comet is capable of making the building blocks for essential biological molecules. Researchers previously found amino acids in samples of comet Wild 2 obtained via the Stardust mission. The researchers ground up samples of twelve carbon-rich meteorites with nine of the samples recovered from Antarctica. The team extracted a sample from each meteorite using formic acid and then ran the sample though a liquid chromatograph to separate the compounds.
The team found the adenine and guanine in the samples, which are nucleobases along with hypoxanthine and xanthine. The latter two are not used in DNA, but are used for biological processes. Inside two of the meteorites the team also found the first traces of three other nucleobase molecules including purine, 2,6-diaminopurine, and 6,8-diaminopurine. A study of the ice surrounding the location the meteorites were found showed that the concentrations of some of those molecules was much lower than in the asteroid suggesting they were indeed formed in space not from contamination.