On a clear December morning, a team of scientists followed a homing beacon into the remote Australian desert to collect precious material from outer space. The shoebox-size capsule, part of Japan’s Hayabusa2 mission, held rocks and dust from Ryugu, a carbon-rich asteroid that likely harbors the building blocks of life. To keep the sample pristine, the capsule was whisked away to the Japan Aerospace Exploration Agency’s (JAXA) Extraterrestrial Sample Curation Center, a lab near Tokyo designed to prevent the cosmic material from being contaminated with earthly organisms.

For years, concerns about planetary protection have focused on preventing Earth from littering the solar system—sterilizing spacecraft and keeping astronauts under strict quarantine protocols. But as space agencies around the world gear up to