Kurgan wrote:
The Moon (or Mars) doesn't have enough gravity to prevent loss of bone mass and muscle atrophy. Furthermore, the Moon has no atmosphere apart from very small amounts of argon and helium, so you won't have anything to convert into oxygen--or anything to protect you from radiation.
We don't quite know that. We know that there will be loss of bone and muscle atrophy in a zero gravity environment but there has not any research into how low gravity between Earth's and micro-gravity will affect muscle or how much bone or muscle will be lost with varying amounts of gravity. The moon does is not a micro-gravity environment, it's gravity is a 6th of the amount on Earth, therefore you would still be using at least some muscle when moving about in the moon's gravity. There may still be some loss in muscle mass but it won't be as much as is seen in astronauts living on a space station. Besides, it can be mitigated by exercise.