What is actually happening when you experience weightlessness?

Answer 1

It is a common misconception that there is no gravitational force acting on the body. On Earth, the Earth's gravitational force pulls us down. We exert a reaction in the opposite direction and hence feel our weight. In space, we do not exert this reaction and hence we feel weightless. Our actual weight however, is not zero.

Answer 2

When a spacecraft is in orbit, anywhere within a few thousand miles in altitude, it and the occupants are in freefall around the Earth. They experience no net acceleration in any direction unless they are changing velocity.

So although the Earth's gravity still exerts a powerful force on them, the horizontal motion of the craft carries it "past the planet" in an arc that is part of a circular or elliptical orbit. If the forward motion of a spacecraft is slowed (as by friction with the atmosphere), it will then be dragged down by gravity.

As compared to weightlessness in orbit, "true" microgravity could be obtained once you are far enough from the Earth, and the gravity decreases to a point where it is imperceptible.

*It could be stated that the centripetal force is in balance with the gravitational force and the astronauts sense a near-zero net force. However, the answer might not comply with what physically happens. A more accurate explanation is in terms of free-fall and the continuing vector change of falling motion.

Answer 3

Weight is caused by gravity; thus you only have weight where you have gravity. However, technically, there is no place in the universe that does not have gravity ... if the universe consisted of a single grain of sand and not one atom more, there would be gravity created by that single grain of sand a billion light years from it -- just not sufficient (and since it would be the only mass in the universe, it would be rather meaningless since it wouldn't have anything to pull).

If you have sufficient altitude to be above the atmosphere (which creates too much drag, preventing objects from going fast enough to have a stable orbit) and in orbit of Earth or any planet or other gravitationally significant object, you actually do still experience gravity, but being in orbit means you have enough momentum (motion) to, essentially, fall over the horizon and you are in constant free-fall, going forward fast enough to never (in a stable orbit) hit the ground. Beyond a certain distance from earth or another gravitationally significant object, you are outside the region in which the object's gravity dominates (the region of space dominated by the gravity of an object is called the object's Hill Sphere, though especially in the case of an irregularly-shaped object (such as an asteroid), or one with moons which have significant gravity compared with their planet (earth and its moon being a good example of this), the shape of the region may not be even close to a sphere) and you would then be within the gravitational influence of larger, more distant objects -- in the case of Earth, whose Hill Sphere extends to about 1.5 million kilometers beyond which you would be within the Sun's sphere of influence (or another planet, if you were close to another planet).

Answer 4

That happens when a spacecraft or space station is in a stable orbit. The craft is in freefall around the Earth, so although gravity is pulling down, the craft falls "past the edge of the planet" in an arc that forms a circular or elliptical orbit.

When launching or landing, the acceleration/deceleration forces are much greater than gravity. When using thruster engines in space, there is a small, gravity-like acceleration force that pushes the astronauts in the opposite direction from the spacecraft motion.

Answer 5

because there is no gravity to pull them down

Improved answer: The answer above is untrue. Of course there is gravity in space, it stretches out through space far beyond the solar system - it does become weaker as the distance between objects increases, but for a space station in orbit around the earth there is almost as much gravitational attraction as there was on earth itself.

The space station is orbiting the earth so that it can be regarded as continually falling, but never landing back on earth, as earth moves below it. Just as in a falling lift (elevator) or at the top of a trampoline jump, the feeling of weightlessness is produced.

Weightlessness happens because there is nothing pushing back on you - you normally feel as if you have weight because the ground or the chair you are in push back on you.

Answer 6

Yes, it is regularly achieved in outer space (free fall).

Yes, it is regularly achieved in outer space (free fall).

Yes, it is regularly achieved in outer space (free fall).

Yes, it is regularly achieved in outer space (free fall).

Answer 7

Astronauts are never "weightless"; a more accurate term would be "free-fall". When in orbit in the Shuttle or ISS, the satellite and everything in it IS falling - but because they are going 18,000 miles per hour sideways, they keep missing the Earth.

The mass of the astronaut or the space station is unaffected. But because they are "freely falling around the Earth", they feel no weight.

Answer 8

You can feel something close to genuine weightlessness out in space when you are far from any big bodies (like a planet or star) which would pull you in through gravity. This is close to true weightlessness (you can never be completely weightlessness unless you are infinitely far away from everything else with matter) as you aren't being pulled down with very much force at all.

You can experience something which feels like weightlessness in planes which fly in parabolic arcs, but this is really just that the plane is falling around you so nothing is holding you up. It is like you are in free fall and you happen to be in a plane which is also in free fall to catch you before you hit the ground and to shield you from the massive drag forces (due to air) outside. Anyway, stuff like planes in free fall or shuttles in orbit around the Earth simulate weightlessness, but you are still being pulled down by the Earth's gravity, so you still have some weight (albeit less the farther away from the surface you go).

Answer 9

Most astronauts never escape Earths gravity. They only feel weightless because they are falling around the earth in an orbit at the same speeed as the shuttle or spacestation they are in. Only the 24 astronauts who have made it to the moon were technically weightless as they traveled through "outer space".

Answer 10

Any object in orbit is essentially falling as fast as it can possibly fall already. They're not actually "weightless", but everything around them is falling at the same speed, so they might as well be.