What are Some of the Effects of Microgravity?

Michael Anissimov
Michael Anissimov

Microgravity is the environment created during weightlessness, in which gravity has a negligible effect. Microgravity is obtained in one of three ways - going far enough from any planet or star's gravity field, falling, or orbiting a celestial body — the same thing as falling but it never stops.

Astronauts must exercise while in microgravity to prevent the bones and muscles from weakening.
Astronauts must exercise while in microgravity to prevent the bones and muscles from weakening.

A common misconception is that gravity disappears when in low earth orbit (LEO), like the International Space Station. This is not the case. LEO is not far away enough from the Earth's surface to have decreased gravity - in fact, gravity there is similar to its intensity on the surface. The weightless effect is only caused because the objects on the space station and that space station are in constant free fall.

Microgravity is obtained by orbiting a celestial body.
Microgravity is obtained by orbiting a celestial body.

One of the most famous effects of microgravity is that a flame becomes spherical. Plants grow towards the source of the light rather than in any specific direction. This same effect can be achieved on Earth to some extent but is even more obvious in microgravity. If objects are left alone, they have a tendency to fall towards the densest part of the spacecraft. In LEO, a small amount of weight orientation is also felt as the very thin air creates a pushback effect in one direction of the orbiting spacecraft. These play a role in why the environment on a space station is called microgravity more often than zero-gravity, though both terms are used.

Microgravity was used historically on Earth's surface to produce highly spherical iron balls for buckshot. By making a tower a couple hundred feet tall and dripping molten iron from the top, the shot would form into spheres due to surface tension, then cool enough during the fall to remain undamaged when they hit the bottom. This was used to mass produce buckshot of high quality. The scientific parallel of a shot tower is the drop tower.

Microgravity is relatively harsh on human beings. It makes our muscles deteriorate, forcing constant exercise. Blood and fluids float freely around the body, sometimes causing a puffy face and stuffy nose. Extreme flatulence is common. It seems likely that once going into LEO becomes more popular, rotating space stations will be built to simulate the presence of gravity and make everybody happier.

Michael Anissimov
Michael Anissimov

Michael is a longtime wiseGEEK contributor who specializes in topics relating to paleontology, physics, biology, astronomy, chemistry, and futurism. In addition to being an avid blogger, Michael is particularly passionate about stem cell research, regenerative medicine, and life extension therapies. He has also worked for the Methuselah Foundation, the Singularity Institute for Artificial Intelligence, and the Lifeboat Foundation.

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Discussion Comments


@bythewell - That is the main reason I would love to experience weightlessness in space at least once in my life. Apparently it makes a lot of people feel very ill for the first few days, like sea sickness does, but I don't care. I'd love to be able to jump do flips in midair, or drift around scooping up bubbles of water or pieces of candy like the astronauts do.


@umbra21 - It's going to be interesting to see what happens when people start to live in colonies on other planets or stations with different gravity rates or no gravity at all. I read a short story recently about kids who grow up on a Mars colony and how they changed to the point where they would never be able to live on Earth, but they could do tricks in the lesser gravity that kids on Earth never could.


I once read that the astronauts who were subjected to microgravity for long periods of time would end up with muscle deterioration everywhere except for their stomach muscles, which would actually become stronger. This was because every time they had to bend down, say, to tie their shoes, they would have to really use their muscles to do it, rather than relying on gravity to help them as we do on Earth.

The muscle deterioration is quite substantial though. One thing that isn't widely known is that after coming back from the moon, the astronauts usually have to be carried from the shuttle, as they simply can't stand on their own anymore in normal gravity.

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