If an astronaut fell off the space station, shuttle, and were untethered for some reason.
Do they have any options?
A parachute could give enough drag for them to fall out of orbit, but would they have enough air to get them far enough? Besides of course the extra weight and bulk of having one strapped on.
What kind of rescue policy do they have?
If they exhaust all rescue attempts, would they still recover the body?
What do you mean “fall off”? If they’re on EVA and somehow come untethered, they’ll just drift there beside the spacecraft. If they happened to push off slightly, they’d drift away slowly, but even there, the orbits would probably bring them back close to the spacecraft in less than an hour.
The most likely response would probably that someone on board the spacecraft would throw them a tether, and tell them to not be an idiot and to actually attach it this time.
Parachutes work near the earth because the atmosphere is so dense that you’ll never reach burn-up speeds. But up in orbit, once you start to fall, you’ll go so fast that the parachute would burn up or melt.
What do parachutes have to do with this though? The astronaut isn’t going to fall back to earth at least in any reasonable time-frame. They are in orbit and will stay there. It isn’t like you can just casually push towards the earth and expect to fall to earth either. Rather large speed changes are the only way to get out of orbit and a stranded space walker doesn’t have a way to do that.
I am really confused about the comments about using a parachute to slow down to drop out of orbit. The OP is aware there isn’t any meaningful atmosphere in orbital space right? Parachutes need air to deploy and do anything.
I sense a number of misconceptions in this thread.
Yes, they will get "close"er again during the next orbital go around, but I doubt they would get close enough to grab something. Maybe close enough to “throw a line” but even thats going to be more chancey than one would probably like. And it certainly wouldn take much of a push off before you were quickly far enough away that a line throw would be a hit or miss afair.
Even if a parachute would work, it really wouldn’t make sense to equip astronauts with them. Much easier to just give them, you know, a tether. Or if you’re worried about a tether breaking, then give them two tethers.
they would utilize the ARD (astronaut retrieval device [ fishing rod with casting reel and sinker on the line ] ). they keep a few mounted on the outside of the space station. casting practice is part of astronaut training.
See Simplified Aid for EVA Rescue for recovery. On the ISS, either the Canadarm on the ISS or the Shuttle (if equipped) would probably be used, or the ARD mentioned above.
For re-entry, see the MOOSE. Note that this has never been tried, though mid-air recovery of film canisters and space-return samples has been performed with varying degrees of success.
It should go without saying that a parachute isn’t going to be of much use in orbit, either in slowing to re-entry speed or protecting the astronaut during recovery, else this would be used other than far more expensive reaction motor and thermal protection systems.
Let’s start with your own misconception regarding the permanence of orbiting satellites. Please read up on orbital decay. See also Skylab, perhaps one of the more famous cases of orbital decay.
If there’s enough atmosphere up there to induce orbital decay, then presumably a large enough parachute could induce drag to accelerate the process.
Well, what would happen if the astronaut jumped as hard as he could towards the earth? Or for that matter away from the earth? How about ‘forwards’ or ‘backwards’ away from the space station?My guess is he or she would settle into some slightly different orbit due to the change in his net speed, but that’s just a guess.
There’s no call to be tetchy about it. Shagnasty is correct that the atmospheric density at those levels (>0.0001 torr) isn’t enough to even inflate a canopy, much less provide significant drag. Skylab’s orbit decayed during a period of unanticipated sunspot activity, causing the thermosphere to expand and resulting in more drag.
Deliberately jumped away from the station? The greatest delta-v an athletic person can achieve by jumping is about 16 ft/s, whereas the ISS is moving at an average speed of 25.3 kft/s, so you can see that the momentum change afforded by “jumping” is a fraction of a percent.
Are any of these explanations based on actual experience? Would YOU volunteer to test out these hypotheses? What you seem to be saying is that if someone released a large bag of heavy tools outside during a space shuttle orbit, f’rinstance, if you had a fairly big net you’d be able to catch it on the next orbit. Amirite?
This seems to suggest that we are not travelling through space, but with it. Whereas my thought was that we’d never have passed through the same bit of space twice in our Earth orbit.
You seem to be implying that the bag of tools just stays there stationary relative to some third party observer while the shuttle just zooms off around the planet. It doesn’t - it’s still floating there with you, but in a slightly more oblong orbit (since it was accelerated to the side/back/front/up/down of your position). During “the next orbit” is where the two orbits intersect.
ivan astikov: perhaps it might help if I point out that toolbag still retains all of the ‘energies of orbit’ (momentum, direction of travel/vector, gravitational-pull(s) felt, etc). Its moving in/through Space in same way that all things it orbits are moving through Space (while being orbitted themselves). Its all ‘relationally’ speaking, I guess.
When/If bag is ‘released’, unless its robbed of majority of its ‘energy’, its gonna keep doing what it would’ve been doing held or not - moving forwards with person who lost possession of it. If it is ‘pushed’ away with purpose, then orbit is changed a small amount from that point of ‘balance’/measurement, and it will have new points at 180/360/etc. Initially, those points will be ~close, but will get further away progressively, from original ‘intersection’ of original orbits. I
When an astronaut “pushes” off, several things happen. It puts the astronaut in very slightly different orbit. It ALSO puts the station very, very slightly different orbit.
Now consider the orbits as two rings encirling the earth. Yes, those rings will be close together where the push off happened. But HOW close will they be at the point? More importantly, because the orbits are slightly different, the two objects are traveling along their respective rings at different rates. This means one object reaches the point of intersection at a different time than the other. If the objects arent at the same place AT the same time, it doesnt matter even if the orbits still perfectly intersect at some point.
So, one orbit after the intial push off, how close will the two come together? I did a really cheesy back of the envelope calculation assuming a one foot per second push off (which isnt particularly fast). My “calculation” indicates on the next orbit they would miss each other on the order of 10,000 feet at the next “intersection”/opportunity. Though my calculation is so cheesy I hesitate to describe it.
Also keep in mind that the two orbits are likely decaying at different rates (though this may be pretty minor). And, with a one foot per second push off, its only going to be minute or two before throwing a line is going to be dicey and not very long after that a real long shot during the initial “oh shit, there he goes!” event.
Let me put it this way. Barring some detailed and correct calculations, I certainly wouldnt be thinking “no problem, catch you on the next orbit!” if I drifted away from the space station.
As the guys above have said, you don’t have to be worried about being cast adrift in space, because you’ll just float a little bit away from the shuttle or rocket. Totally counter-intuitive , but apparently it all makes complete sense. I suppose that this means that if an astronaut climbed out of the rocket after it had left the atmosphere, he could sit on the nose-cone and ride through space?
