During long-duration missions, astronauts will often experience isolation and confinement.

Not a few astronauts had experienced grave psychological problems by choosing the wrong coordinates when they started on a compli- cated job.

For five minutes, at maximum altitude and traveling more than 5,000 miles an hour, the astronaut experienced the weightlessness of space.

The astronauts experience the same effect, falling with the space shuttle.

In addition, after long space flight missions, male astronauts may experience severe eyesight problems.

After long space flight missions, astronauts may experience severe eyesight problems.

On earth the force is 1g, but astronauts experience unusually high and low g-forces.

Some astronauts experience such sensations upon standing after the shuttle lands.

The astronauts, zipping around the Earth at 17,500 miles an hour, have experienced other ripples of earthly turmoil.

As the length of the mission increases, the astronauts may experience cumulative or chronic stress over an extended duration of time.