# Can an Astronaut Do a Backflip in Space?

• jaldenpage
In summary, if an astronaut were stranded in the center of a room without any means of propulsion and unable to push off of anything, they could theoretically do a 360 degree backflip (or forward flip).
jaldenpage
This isn't a homework problem or anything, it's just something I'm in a debate with someone about. Theoretically, if an astronaut were left stranded in the center of a room without the ability to push off of anything and without any means of propulsion -- would the astronaut be able to do a 360 degree backflip (or forward flip)?

Does this movement require gravity, momentum, or the ability to push off of another mass?

I would say that they absolutely could do a flip. They would just need to windmill their arms, and due to conservation of angular momentum, their body would rotate in the opposite direction from their arms.

If a human can do this rotation, does this mean that in theory a spaceship that is moving but not accelerating could choose to start rotating simply by moving its parts correctly? I'm talking about a rotation with little to no effect on direction and without using thrust.

jaldenpage said:
This isn't a homework problem or anything, it's just something I'm in a debate with someone about. Theoretically, if an astronaut were left stranded in the center of a room without the ability to push off of anything and without any means of propulsion -- would the astronaut be able to do a 360 degree backflip (or forward flip)?

Does this movement require gravity, momentum, or the ability to push off of another mass?

I'm also going to say yes, because cats are able to right themselves in free-fall. Whether or not an astronaut is flexible enough to copy the motion, I can't say.

http://helix.gatech.edu/Classes/ME3760/1998Q3/Projects/Nguyen/

The site specifically mentions that humans have so far been unable to copy the motion.

http://web.archive.org/web/19980528...g/publications/technique/1997/2/twisting.html

Seems to indicate there is a difference between twisting and flipping as well.

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jaldenpage said:

If a human can do this rotation, does this mean that in theory a spaceship that is moving but not accelerating could choose to start rotating simply by moving its parts correctly? I'm talking about a rotation with little to no effect on direction and without using thrust.

Yes if the spaceship were designed to be able to do this. If the ship was one ring inside another ring and could rotate, then the act of rotating would cause the outer ring to spin opposite of the inner ring.

jaldenpage said:

If a human can do this rotation, does this mean that in theory a spaceship that is moving but not accelerating could choose to start rotating simply by moving its parts correctly? I'm talking about a rotation with little to no effect on direction and without using thrust.

Yep. See "reaction wheels" and "control moment gyroscopes" for details. Many satellites use these techniques for attitude control, since they don't need any fuel.

I wonder if a cat, already knowing it is fully or partially inverted prior to fall, does not start the twist prior to drop/release, thus using the static holder as a twist initiation.

A very good video of a falling cat. It's clear there is no need to push off the static holder.

It's all in the way it alternatively adjusts the lengths of its legs:

1. Bend forward legs + extend backward legs simultaneously,
2. Twist waist half-way : this right-sides up the torso and head,
3. Bend rear legs + extend forward legs,
4. Twist waist half-way : this right-sides up the butt.

It's all there is to it.

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Excellent video! the cat looks like it's counter-rotating about the spine... too cool.

jaldenpage said:
If a human can do this rotation, does this mean that in theory a spaceship that is moving but not accelerating could choose to start rotating simply by moving its parts correctly? I'm talking about a rotation with little to no effect on direction and without using thrust.

That's what Hubble does if memory serves me well.

Andy Resnick said:
Whether or not an astronaut is flexible enough to copy the motion, I can't say.

I don't think you need to be specially flexible, seems to me that just rotating your arms should do the trick.

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## 1. Can a human do a backflip in space?

Technically, yes, a human can do a backflip in space. However, due to the lack of gravity, it would not be the same as a backflip on Earth. In space, there is no force pulling the body back down, so the person would continue rotating until they stopped themselves.

## 2. Is it more difficult to do a backflip in space?

Yes, it is more difficult to do a backflip in space. Without the pull of gravity, it requires more effort and control to rotate the body. Also, in space, there is no air resistance to help slow down the rotation, making it harder to land the backflip.

## 3. Can astronauts do backflips in space?

Yes, astronauts have done backflips in space during spacewalks or inside the International Space Station. However, they are trained professionals and have to be careful not to accidentally hit equipment or walls while flipping.

## 4. What happens if you try to do a backflip in a spacesuit?

It would be extremely difficult, if not impossible, to do a backflip in a spacesuit. The bulky and pressurized suit restricts movement and makes it challenging to move the body in a controlled way. Additionally, the helmet could obstruct vision, making it even more challenging to perform a backflip.

## 5. Is it safe to do a backflip in space?

While it is possible to do a backflip in space, it is not recommended for safety reasons. Without the pull of gravity, it is challenging to control the body's movements, and there is a risk of colliding with objects or losing orientation. Astronauts are trained to move carefully and efficiently in space to avoid accidents.

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