In science fiction movies, man travels through space with no problem, hopping from universe to universe, but the reality is, man was not built to travel through space. NASA says there are many problems the human body goes through in space; many they still haven’t been able to solve.

After 50 years of space flight, problems of space travel still elude doctors including one that they noticed just five years ago. Some astronauts eyeballs seem to be somewhat squashed after traveling in space.

Other problems humans face during space travel, and one of the biggest, is radiation. Without the Earth’s magnetic field, space travelers receive high doses of radiation which heightens the chance of cancer.

Another problem is that human bodies are made up of 60% water and in space liquids float up to the chest and head. Astronauts say after space travel your head feels the same as if you have hung upside down for several minutes. Your face puffs up and pressure inside the skull rises.

Some other problems: bones become brittle, trouble sleeping and eating and vision is affected with a shift toward farsightedness. NASA is now checking astronaut’s eyesight before, during and after flights.