Eye Vision of an Astronaut

NASA thinks that long missions can give astronauts vision blurs. They think it's because of a force pulling behind the astronaut's eyes called microgravity. This can smash the astronaut's eyes. So just in case NASA keeps the international space station stocked with glasses.

The Long Term Physical

Each astronaut has to pass a long term physical. You have to have 20/20 for each eye. It is correctable with laser eye surgery and glasses are acceptable. You must stand between 5'2 and 6'4. Blood Pressure: must be 140/90 in a sitting position. Height between 58.5 and 76 inches.

Bones and DNA

Astronauts lose an average of more than 1% bone mass per month. On earth that's how much an aging man or woman would lose in year. The DNA molecules are knocked apart , so on a long journey in space they may have to try methods like gene changing medicine to make the DNA stronger. If molecules are ripped up it could cause cancer or dementia.

No Alcohol in Space

Astronauts can't have alcohol in space. That is because NASA thinks your alcohol blood level gets too high when you are flying. Alcohol in space would be dangerous. I do suggest that if you want to be one to never try alcohol, so that you won't miss it too much , and drink too much when you get back to earth.

Atrophies

Astronauts might get atrophies. Heart atrophy means the heart muscle is wasting away. Bone atrophy is when the bones waste away. Now you clearly know the meaning of atrophy, It means wasting away. Astronauts lose heart mass when they are in space for a long time. Not many astronauts get heart atrophy though. When they are back on earth , gravity is back and the heart will beat normally.

Blood Loss

Astronauts can lose a lot of blood within 2-3 days in space. About 22% blood volume. Bodies may need to make more blood after returning to earth.