Quick Zero Gravity Question

[Toby Frost]

In TV and film, when spacemen are moving in zero gravity, they’re often depicted as moving very slowly. Actual astronauts seem to move slowly when outside their craft, but at normal speed when indoors. Is there a particular reason for this other than just caution?

 

[mosaix]

In TV and film, when spacemen are moving in zero gravity, they’re often depicted as moving very slowly. Actual astronauts seem to move slowly when outside their craft, but at normal speed when indoors. Is there a particular reason for this other than just caution?

Apparently, it’s very difficult to stop when moving fast in low gravity.

 

[-K2-]

Well, I just watched some videos of inside the ISS. Off the top of my head, though 'caution' is a good guess, I'd also think that the confines/rigidity of a spacesuit might be part of the reason, and also the added caution of not being in a secure/enclosed area. But I'm just guessing. I bet there is an answer out there on google for this though.

K2

 

[Laughingbuddha]

I have just been on the public lecture of Russian astronaut Mikhail Kornienko, where this question was answered, and yes, its mostly caution, because there is no "up" or "down" or any feeling of direction whatsoever, so you easily can hit something if you gain a lot of speed (don't forget that while you have no weight, your mass and thus inertial moment are still there with you). And of course the suits for going into open space are somewhat rigid and restricting your free movement to the significant degree. But mostly it is a caution - not to fly away and not to accidentally throw away something, because you know, if it's not connected there is absolutely no way to get it back.

 

[Star-child]

There is also the question of fuel or motor power if they are standing on the shuttle arm. Speeding up and slowing down in space takes more fuel or larger/heavier electric motors if the change in speed is greater. 0-2mph-0 is half the energy of 0-4mph-0. And no matter how much fuel you have on board the spacesuit, the nozzles only have so much output per second - so you can't "slam on the brakes" if you build up a lot of velocity.

Also, with no gravity or air, rigid things tend to bounce off each other really well. A spacesuited astronaut the bumps the side of the shuttle at 5mph is likely to go tumbling away at nearly all of that velocity.

 

[Toby Frost]

Thanks everyone. That's pretty much what I thought but it's useful to have it confirmed.

 

[.matthew.]

Having bought Space Engineers over the weekend I can attest that flying into solid objects at high speed hurts...

 

[tinkerdan]

You might consider that when training on the ground they often train underwater with the tasks that they expect to be accomplishing in space, so there is a correlation between working in space and working under water.

Part of this is the bulkiness of the suit. Like walking inside a designer balloon and even though you are 'weightless' you are weightless with twice the bulk and twice your normal weight(if that makes any sense).

And then the caution--both with putting yourself in motion and lossing your footing and ending up at the end of your tether tumbling around trying to reel yourself back in and with worry about whatever you are working on and possibly losing tools and parts as they float away if you lose your grip on them. All the time the field of vision is limited by what your helmet allows. Possibly limited by the light source they have for the work they need to do. Then there is the possiblility of getting snagged on something and compromising the seal on your suit.