The LEIA mission aims to prepare humans for long-term travel to the Moon and Mars by delivering yeast to the lunar surface and studying its response to radiation stress and gravity. Yeast DNA has a lot in common with human DNA, including the way cells work to repair damage caused by radiation. As NASA prepares to send humans further into space for longer durations, LEIA’s research will inform efforts to protect astronaut health and safety, as well as how to produce microbial foods and drugs on the Moon and Mars.