Planetary Protection

The risk of bringing potentially hazardous material back to Earth in a returned sample. Sample-return missions are designed to contain their cargo as strictly as the most dangerous pathogens, so nothing escapes before it is shown to be safe.

The risk of carrying Earth microbes to another world on a spacecraft, which could harm any native biosphere or, worse, be mistaken for alien life. Missions to Mars and the ocean worlds are cleaned and sterilised to strict standards to prevent it.

The careful containment, quarantine, and curation of returned samples in specialised facilities — keeping them pristine for science while keeping Earth safe, and preserving them for study by instruments not yet invented.