Why are astronaut’s movements in space seemingly slow motion when there’s no air/water resistance to slow them down?
In: Physics
Since there is no resistance there is no way to slow down. It allows them to move around with that huge spacesuit. Fast moves can cause a big response. Any bump in the wrong direction may cause them to lose control. Therefore everything is in slow motion.
Even if you have not air/water resistance the suites sill have mass that you need to accelerate. The suites used on the moon had a total mass of 200 lb (91 kg) so the movement is a bit like if you would push the same amount of mass in forn of you in a cart on wheels with no friction like a shopping cart that you put a adult human in. It is a lot harder to move if you push a cart like that even if there is not wheel friction.
On the moon the gravity is 1/6 of earth if you look at a lot of videos the do not exactly waling but more skipping a long and the rate that they fall toward the surface is 1/6 of what we are used to and it look like slow motion.
There might no be any external resistance but the astronauts are in a pressure suite and bending it require force. Look at a apollo space suite without any protective outer layer [https://www.wikiwand.com/en/Apollo/Skylab_A7L](https://www.wikiwand.com/en/Apollo/Skylab_A7L) and at the joint you bend. It is a bit like bending a balloon or a water pipe that is pressurized and it require a force. The skipping around on the moon instead of walking have a lot to do with the fact that thee suites are hard to bend.
The space suite that is used today on ISS for the US is the [Extravehicular_Mobility_Unit](https://en.wikipedia.org/wiki/Extravehicular_Mobility_Unit) that have a total mass of 319 lb (145 kg) When you are weightless the lesgs are almost useless on the outside of the space station so the astronaut move around by pulling themselves with the hand. So lay on a low friction shopping cart that have a the same mass and pull yourself along with you hand. You also need to move safety line along because you what to be attached to the station all the time. You do also need to avoid bumping stuff to protect your self and the space station slow and safe way is user.
If you look at videos of EVAs on ISS you notice that the might move around quite slowly but arm movement can be faster because today there is rotation pressure joint is the suites. You can see them on the future models at [https://youtu.be/4QVeNY4HdNM?t=166](https://youtu.be/4QVeNY4HdNM?t=166). The current have similar joints in the shoulder, waist, elbow and wrist that the Apollo suited did not have.
It’s precisely because there is nothing to slow them down. They move deliberately because if you flip something it’s not going to be slowed down by air. Move your arm too fast, and you’ll rap your wrist on something. “Every action has an equal an opposite reaction” said Newton, and without gravity to stick you to the ground that reaction has to come from your other hand or some Velcro gizmo.
There are a few reasons. Their suits are pressurized. The joints of these suits want to fully extend due to this pressure. This makes it difficult to move and do things, and reduces precision substantially. Not only this, but the suits are quite heavy, and have inertia to slow movements. Lastly, the astronauts do not have anything to stand on. Fast movements will make their bodies start to rotate and further reduce the precision of their motions.
Because if you drop something in space, its gone forever,so they try to be extra careful. The first spacewalk was almost a total disaster due to the pressure difference turning the astronaut into a giant balloon man. Aleksey Leonov was almost unable to bend his joints at all and get back into the capsule.
Two other considerations are consumables and training.
If they work hard (starting/stopping/rapid motions) they will breathe out more carbon dioxide as a result of the extra effort. The life support system on the EMU has a finite ability per spacewalk to scrub CO2 out of the breathing gas. Harder work = shorter spacewalk.
The other reason is that a good deal of in-the-suit spacewalk training is performed underwater where there is definitely is a lot of drag. This results in the normalization of slower motions during training that carries over to the actual spacewalks.
Edit: autocorrect
Your actions on earth are made safe by gravity keeping you anchored and effectively eating most of the energy your muscles produce.
Your muscles are incredibly powerful. They can lift your entire body from a sitting to standing position with very little effort, a dead lift of 80lbs is so easy that it does not even register to you as a meaningful expenditure of energy.
In micro-gravity standing up with that same force would send you painfully crashing into the surface directly above you.
Any movement of your arms would add rotational energy that you wouldn’t be able to counteract without holding on to something that would anchor you and eat that energy. When you throw a ball if you lean into the throw then you might have to extend a leg behind you to act as an anchor and keep you from falling forward. In microgravity you’d just start spinning, possibly with a leg extended in a goofy way.
An object in motion will remain in motion unless acted upon by an outside force. Down here on Earth, this force is gravity. Up there they don’t have that. So if they stood up really fast from their chair they’d keep going up, until they bounce off the ceiling, then ricochet back down like a ping pong ball. So they move super slow to keep from not being able to stop.
It depends on gravity. We haven’t really landed people anywhere else so I’ll assume you’re talking about the moon landings and various spacewalks. These scenarios all have lower gravity than on the surface of the earth so the astronauts tend to float a little easier, making them appear as if they are in slow motion.
Good answers, but one factor hasn’t been mentioned yet that has nothing to do with reality: in movies and TV, it’s really difficult to capture the look of low- or zero-gravity on Earth, So many TV shows and movies will literally film the astronauts in slow motion to make things look a bit more “floaty”. This was especially true for older and cheaper stuff that didn’t have access to good CGI or a “vomit comet” aircraft.
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