Low Gravity, Zero G, and Weightlessness
Many people think that weightlessness is a strange and even dangerous condition, but there's nothing particularly weird about it. Anyone can experience it (briefly!) by just jumping into the air, or for up to about a second by jumping off a wall. While you're airborne your body is in weightlessness. Trampolinists and high divers experience weightlessness for up to a few seconds.
Some people say "they feel their stomach jump", and that's quite right. Normally when standing up your stomach is pressing down on the organs below it (your guts), pulled down by gravity. But when you jump in the air, all parts of your body fall at the same speed, so your stomach no longer presses down on the parts below it. It "floats".
If you "stand on your head" your face goes red because blood which is normally trying to fall down into your feet when you're standing upright now tries to fall into your head. Being in zero G is in between the two - more like lying down. The fluids in your body are no longer trying to fall into your feet, and so people's faces tend to swell and become rounder than they are on Earth.
If you stay in zero G for months, your bones start to lose mass and get thinner, since they're not carrying weight. To counteract this you need to do particular exercises. But for a few days or weeks these effects are no problem. Also, in getting used to zero G your head learns to ignore what your inner ear is saying about your balance, so some people have some giddiness on their return to Earth (hence the chairs sometimes used by Russians returning from space; it's not because they're "basket-cases" as some newspapers have liked to suggest! Overall, a short stay in orbit has no ill effects.
So what is actually going on when astronauts are in 0 gravity? It can more accurately be called weightlessness or free fall. This is acutually the result of Einstein’s Physics. Free fall is the effects of weightlessness created when an object falls solely under the acceleration of gravity. The best way to explain this is Eistein’s elevator illustration. Say that you were in an elevator that was suddenly falling from a great height. Since its is an enclosed space you would not be subject to factors like air resistance. So in your own frame of reference it would seem that you are actually floating free of gravity. Zero gravity would only exist as your personal perception in the elevator.
This is what happen with freefall. Back to the space shuttle. What happens is that space shuttle is travelling with constant acceleration similar to that of gravity. This creates the 0 g effect for astronauts. Another interesting thing about the state of weightlessness is the effects that it has on the human body after a long period of time. It has been observed that astronauts who spend a considerable amount of time in space lose bone mass and atrophy of certain muscles. This is because the human body was adapted to exist under the influence of gravity, providing density to bones, and exerting consistent stress on muscles even when at rest.
Many people think that weightlessness is a strange and even dangerous condition, but there's nothing particularly weird about it. Anyone can experience it (briefly!) by just jumping into the air, or for up to about a second by jumping off a wall. While you're airborne your body is in weightlessness. Trampolinists and high divers experience weightlessness for up to a few seconds.
Some people say "they feel their stomach jump", and that's quite right. Normally when standing up your stomach is pressing down on the organs below it (your guts), pulled down by gravity. But when you jump in the air, all parts of your body fall at the same speed, so your stomach no longer presses down on the parts below it. It "floats".
If you "stand on your head" your face goes red because blood which is normally trying to fall down into your feet when you're standing upright now tries to fall into your head. Being in zero G is in between the two - more like lying down. The fluids in your body are no longer trying to fall into your feet, and so people's faces tend to swell and become rounder than they are on Earth.
If you stay in zero G for months, your bones start to lose mass and get thinner, since they're not carrying weight. To counteract this you need to do particular exercises. But for a few days or weeks these effects are no problem. Also, in getting used to zero G your head learns to ignore what your inner ear is saying about your balance, so some people have some giddiness on their return to Earth (hence the chairs sometimes used by Russians returning from space; it's not because they're "basket-cases" as some newspapers have liked to suggest! Overall, a short stay in orbit has no ill effects.
So what is actually going on when astronauts are in 0 gravity? It can more accurately be called weightlessness or free fall. This is acutually the result of Einstein’s Physics. Free fall is the effects of weightlessness created when an object falls solely under the acceleration of gravity. The best way to explain this is Eistein’s elevator illustration. Say that you were in an elevator that was suddenly falling from a great height. Since its is an enclosed space you would not be subject to factors like air resistance. So in your own frame of reference it would seem that you are actually floating free of gravity. Zero gravity would only exist as your personal perception in the elevator.
This is what happen with freefall. Back to the space shuttle. What happens is that space shuttle is travelling with constant acceleration similar to that of gravity. This creates the 0 g effect for astronauts. Another interesting thing about the state of weightlessness is the effects that it has on the human body after a long period of time. It has been observed that astronauts who spend a considerable amount of time in space lose bone mass and atrophy of certain muscles. This is because the human body was adapted to exist under the influence of gravity, providing density to bones, and exerting consistent stress on muscles even when at rest.
See below how Astronauts are doing their works in Space Station in Zero (0) Gravity level:
