Key ingredient of life might have come from comets

Ribose could form in space despite the harsh conditions.

NASA, ESA, and the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration

Life on Earth might not have developed as we know it without a little sprinkling of sugar from space. A new study by a group of French scientists suggests the possibility that early Earth got its first dose of the simple sugar ribose from comets. Ribose, as you might know, is an important ingredient in RNA, which is one of the three macromolecules essential for life.

Scientists believe that there was a period in the history of our planet known as RNA World, wherein RNA was the only genetic material present. And since early Earth was too hot for organic molecules to survive, some scientists also believe that the building blocks necessary to form the first genetic materials could have hailed from space. "At a certain point in prebiotic evolution, the availability of ribose would have been, therefore, necessary for life to have started," team leader Cornelia Meinert from the University of Nice Sophia Antipolis told Space.

To test whether ribose could have formed in such a harsh environment, the team recreated the early solar system's conditions in the lab. Specifically, they created simple ices made of water, methanol and ammonia, which were abundant in the early solar system and were found on Comet 67P/Churyumov-Gerasimenko by the Philae Lander. They exposed the ices to radiation that simulated what a young sun would have given off and then left them in room temperature. When the samples evaporated, they left behind not just ribose and other sugars, but also amino acids, alcohols and other organic molecules.

Meinert said their "ice simulation is a very general process that can occur in molecular clouds as well as in protoplanetary disks. It shows that the molecular building blocks of the potentially first genetic material are abundant in interstellar environments." If organic molecules from space truly helped spark the beginning of life on Earth get started, then they could also play a part in the development of life elsewhere in the universe.