Cosmic rays help to form the Universe's complex organic molecules — the building blocks of life on Earth.

The interstellar gas clouds that give birth to stars and planets are rich in organic molecules, but scientists have struggled to explain how these formed. A team led by Ralf Kaiser at the University of Hawaii at Manoa in Honolulu looked into it in the lab, using supercold ices to approximate conditions found in space. They showed that cosmic rays can trigger previously unknown chemical reactions that form sugars and other organic compounds in ice as cold as 10 kelvin. These compounds could sublimate into the gas clouds that become stellar nurseries, and eventually lead to the formation of biological molecules.

The discovery should help to explain the origin and evolution of the molecular make-up of the Universe.

Proc. Natl Acad. Sci. USA http://doi.org/bk46 (2016)