The recovery process Just testing That is the main point about the experiments that Glenn performed in orbit. His reactions to zero gravity and his recovery from it will be different from the younger astronauts. It is expected that he will be more affected by stress and take longer to recover than the other astronauts. Discovery's crew included two doctors. Nasa denied that they were included to keep a watchful eye over Glenn's health in space.
Weightlessness can deplete the strength and minerals in astronauts' bones.
On Earth many elderly people suffer from diseases that give them brittle bones for similar reasons. Scientists have pointed out that to make sense of Glenn's experiments other elderly people will have to follow him into space on future missions. The BBC is not responsible for the content of external internet sites.