Would astronauts need to be germ-free for Mars, and who could go?

"Minor administrative change made to remove the reference to NID 8715.129, Biological Planetary Protection for Human Mission to Mars, that was cancelled by the responsible office."

"This directive defines NASA roles and responsibilities and the procedural requirements, informed by Committee on Space Research (COSPAR) Planetary Pro... guided by the COSPAR policy and guidelines, as amended August 2020 (see for Appendix D additional information), as an accepted approach for demonstrating compliance with the Outer Space Treaty."

"All missions to the Moon and beyond are assigned a categorization for the outbound phase. Missions returning samples to the Earth-Moon system are assigned a categorization for the return phase in addition to the outbound planetary protection mission category."

"Reviews for concurrence the proposer's or project's preliminary planetary protection mission categorization request."

"Treaty on Principles Governing the Activities of States in the Exploration and Use of Outer Space, Including the Moon and Other Celestial Bodies (the "Outer Space Treaty"), October 19, 1967, Article IX."

"The PP discipline is grounded in the Outer Space Treaty (OST) of 1967... Article IX of the OST focuses on controlling the risk of harmful contamination during exploration and research of outer space and avoiding adverse effects to the Earth from the introduction of extraterrestrial matter from other solar system bodies."

"It should be noted that the OST does not explicitly define “harmful contamination.” The interpretation of “harmful contamination” changes as exploration technology evolves and scientific studies provide more knowledge."

"For this reason, NASA’s PP policy and technical standard are informed by COSPAR policy, but additionally provide the detailed requirements for PP implementation by NASA missions and NASA-partnered missions to demonstrate compliance with the OST."

"The proposed update would introduce a Probabilistic Risk Assessment (PRA) framework alongside the existing prescriptive approach. Under the probabilistic pathway, missions would use mission-specific modelling of contamination pathways and controls to demonstrate that the probability of a contamination event does not exceed 1 × 10⁻⁴ per mission during the 50-year Period of Biological Exploration (P"

"This represents an important evolution in planetary protection for future Mars missions, providing a risk-based pathway while maintaining the fundamental objective of protecting Mars and preserving the integrity of life-detection science."

"In 2019 NASA’s Planetary Protection Review Addresses Changing Reality of Space Exploration – a report Friday with recommendations from the Planetary Protection Independent Review Board (PPIRB) the agency established in response to a recent National Academies of Sciences, Engineering, and Medicine report and a recommendation from the NASA Advisory Council."

"Determine if a precursor mission is necessary"

"This meeting series first identified a prioritized list of knowledge gaps that, if addressed, would permit development of an implementable planetary protection policy for the initial crewed Mars mission."

"Before lift-off from Earth and before landing back on Earth, all surfaces and crew of the spacecraft should be screened in as much detail as possible, for example, by WMS."

"The three main topic threads considered within the meeting series were: microbial and human health monitoring; natural transport of terrestrial biological contamination on Mars, and; technologies and operations for contamination control (of spacecraft systems)."

"Each human body is accompanied by 3.8 × 10 13 microbial cells [ 4 ] and thus every crewed mission will include numerous microorganisms introduced by the humans’ “microbial cloud” [ 5 ]."

"(i) protection of the terrestrial ecosystem from possible Martian life;"

"Planetary protection protocols (National Research Council, 2002 , 2006 ; COSPAR, 2005 ) have been established in order to mitigate forward contamination of other planetary bodies, with an exclusionary principle adopted for Special Regions."

"Besides numerous technical issues, one of the major challenges is the protection of the human crew from illness and infection caused by harmful biological contaminants."

"In that case, strict quarantine should be imposed until planetary protection is ensured."

"A Special Region on Mars is defined as “a region within which terrestrial organisms are likely to propagate, or a region which is interpreted to have a high potential for the existence of extant martian life forms”"

"To date, serious infections during space travel have been limited to mostly superficial skin infections [ 21 ]. Among 742 astronauts, 29 infectious disease incidents in the urinary tract and subcutaneous skin infections were reported [ 21 ]."

"Results support the conclusion that a crewed rover traveling over previously undisturbed terrain may not significantly contaminate the local terrain via airborne dispersal of propagules from the vehicle."

"When humans are exposed to stress and extreme environmental conditions, as they would experience during a spaceflight, the immune system is negatively affected, and susceptibility to infection is increased [ 114 , 115 ]."