NASA eases planetary protection rules, reviving 1964 contamination standards for Mars missions

NASA has issued a new directive that relaxes its planetary protection rules, moving away from the stringent 1969 standards that have limited Mars exploration for decades. Administrator Jared Isaacman sent a message to staff stating that advances in sterilization and a slower pace of human spaceflight justify returning to the original 1964 COSPAR requirement of a one-in-10,000 probability of introducing Earth microbes to Mars.

The agency will conduct a “modernization assessment” of contamination science and technology, with findings due by December 2026, potentially lowering the acceptable risk even further. Isaacman emphasized that the change will enable faster missions, increase scientific output, and support future crewed journeys to Mars. He noted that maintaining the more conservative COSPAR measures could affect not only NASA’s robotic and crewed projects but also international, commercial, and private missions. NASA has not responded to requests for additional comment.