Someone had to decide the Moon was not dangerous. It was a committee, and it took three missions.

Before Apollo 11 there was no way to establish whether lunar material carried anything biologically active. Absence of evidence was the only evidence available, and it is not the same thing as evidence of absence. Rather than let the flight programme rule on its own risk, an Interagency Committee on Back Contamination was established in 1966 as the policy-making board for quarantine, drawing in the agencies responsible for public health and agriculture alongside NASA and academic members.

For Apollo 11 the committee designated a specific official — the Manned Spacecraft Center's Director of Medical Research and Operations — as the agent able to impose quarantine on the crew, the spacecraft and the returned lunar material at any phase of the mission, and authorised him to appoint people at each location who could exercise that authority. Quarantine was lifted from the crew and those isolated with them after a 21-day observation period, on the basis of medical and biological data gathered during it.

Early in 1970, with results from two lunar landings in hand, the committee reviewed the requirement. Given what had been found on the Moon, crew quarantine now appeared superfluous, and after lengthy discussion the committee recommended to the NASA administrator that it be discontinued — while holding that biological examination of the samples and containment practice in the lunar receiving laboratory should continue. The precaution was narrowed to where uncertainty remained, and it was not narrowed all at once: quarantine stayed in force for Apollo 14, which was to take a deep core sample that might differ from surface material.