A report published September 30, 2026, said NASA had restored a 1964 planetary-protection threshold for each Mars-bound mission: less than a 1-in-10,000 chance of biocontamination. Planetary protection means preventing Earth life from contaminating other worlds—a safeguard that matters especially when spacecraft search for signs of life.
The reported threshold and the earlier rules
The Committee on Space Research (COSPAR) set a threshold of less than one chance in 10,000 in a 1964 resolution addressing the risk of exposing a potentially habitable or inhabited world to terrestrial life capable of interplanetary colonization. Rules codified in 1969 were described as more stringent. The 2026 threshold was reported specifically for each Mars-bound NASA mission.
NASA's assessment was due to deliver recommendations in December 2026
NASA planned to assess current science and technology related to contamination risk, with recommendations due by December 2026. Those recommendations could lower the threshold further.
NASA said life-search missions would retain protections
NASA said missions searching for past or present life on Mars, including Perseverance, would retain requirements suited to protecting those investigations. Some rocks examined by Perseverance have yielded possible ancient biosignatures, giving the rover's life-search work direct relevance to planetary-protection rules.
