A study funded by NASA and published in the journal PNAS suggests that the chemistry produced in comets and meteorites would have the ability to generate complex organic molecules such as those that are part of deoxyribonucleic acid or DNA. It is not the first time that components of this type have been found, but the doubt about whether they came from contamination with terrestrial life, or had arisen in space, does not fit in the cases that have now been analyzed.
According to statements by Michal Callahan of NASA’s Goddard Space Flight Center, collected by the Sinc Agency, “DNA components have been discovered in meteorites since 1960, but scientists were not sure if they were really created in space or they came from contamination with terrestrial life “. The team of scientists has obtained, for the first time, three lines of evidence that allow them to affirm that these molecular building blocks of DNA were created in space.
Scientists at the Goddard Center have sampled 12 carbon-rich meteorites. In them they found adenine and guanine, two of the four nitrogenous bases or nucleobases that make up DNA . In addition, hypoxanthine and xanthine have been found, also participating in some biological processes.
Three evidences for a conclusion
The first evidence proving that the components found in meteorites come from space is that in two of the meteorites they found for the first time traces of three molecules related to nitrogenous bases. Two of them are very rare in biology. These compounds have the same core molecule as nucleobases, but with added or removed structure.
The second evidence the researchers find focuses on the analysis of an 8 kilogram sample of ice that surrounded the nine asteroids found in Antarctica. The amounts of nitrogenous bases, hypoxanthine, and xanthine in ice were significantly lower than in meteorites. Furthermore, analogous nucleobases were not found in the ice.
Finally, the Goddard Center team demonstrated in the laboratory that nitrogenous bases, both biological and non-biological, can be produced with non-biological reactions. This, according to Callahan, “provides a plausible mechanism for their synthesis in the asteroid’s ‘parent’ body and supports the idea that they are extraterrestrial .” In fact, and according to the scientist, “it seems that there is a class of meteorites, called CM2, where the conditions are suitable to manufacture more of these molecules.”
