The isolation following Apollo missions was to keep Earth from being infected by anything from the moon, and to prevent contamination of the rock samples they brought back. Didn’t have much to do with contaminating the moon; procedures for that were taken prior to the launches.
According to Chaikin, they stopped isolating the astronauts after three missions because they were pretty well convinced there was nothing coming back from the moon to cause us problems. The astronauts didn’t like it for sure, but I don’t know how much of a factor that was in the decision.
Also in Chaikin’s book, he relates the opinion of scientists who made the same point you did about lunar contamination being very unlikely. One pointed out that if he wanted to build a giant sterilization machine, it would look remarkably like the surface of the moon.
To be fair though, when Apollo 12 brought back the camera from the previously soft-landed Ranger probe, scientists were amazed to discover that bacteria that it had accidentally been contaminated with before leaving Earth had actually survived for several years on the Moon’s inhospitable surface!
Still, I think the main concern wasn’t ‘contaminating’ the Moon so much as ruining any biological experiments those and future missions carried out. This is certainly true for unmanned probes. The number one experiment they all do is look for signs of life, even the existence of the most basic organic materials. Hard to do this if some engineer blows snot all over it before it leaves Earth!
I’ve heard that the post-mission quarantine wasn’t to protect against hypothetical moon germs, but to protect the astronauts against Earth germs, in case their immune systems had been weakened by the stresses of space (zero or low gravity, increased radiation, lack of exercise, probably shortness of sleep, etc.).
Never heard that one. I suppose it’s possible, but one of the main objectives of the Gemini program was to see what happened to the astronauts during flights that went as long as a lunar mission.
Jim Lovell and Frank Borman stayed up for nearly 14 days during Gemini 7 for exactly this purpose. But one factor they couldn’t control for was radiation, since a lunar mission would be subjected to different amounts than in Earth orbit.
During Apollo training the crews even spent a night in the Lunar Module simulator to train for sleeping on the moon, and they planned schedules carefully for rest. Not sure if they were worried too much about lack of exercise during a two week flight, but they were thorough enough that I bet they considered it.
An interesting read on NASA’s better efforts for studying long term space flight on human physiology is Homesteading Space - The Skylab Story. Along with a lot of solar astronomy, the astronauts themselves were the main scientific subjects on Skylab. They were on carefully controlled diets before, during and after the flights. Didn’t sound pleasant, but perhaps worth it given the great view.
