Effects of Microgravity on the Body: Being weightless, physical effects, long-term effects on muscles and bones.
- Orbiting in space creates a nearly weightless effect for humans. It is called microgravity. You can experience microgravity by riding roller coasters or jumping on a trampoline or off a diving board. It is the "free fall" period of these activities when the microgravity occurs, and of course only lasts for a short period of time. The shuttle is held in orbit by gravity as it “falls” around the Earth. The force of microgravity in the shuttle is 1 X 10-6 gravity, so objects appear to be floating. It is sometimes called zero gravity, but is more accurately named microgravity because it is so slight.
- Since weight is measured by the pull of gravity on a mass and mass is the amount of matter in a substance, astronauts lose weight due to less gravity. They will also lose some muscle mass because they do not use them due to the lesser gravity in space. If muscles are not used, they will wither.