What precautions are there in case an astronaut loses their connection?

[Drunkrobot]

There has been a lot of talk about Gravity, and the things in real life space exploration that it presents (By the way, if you want to mention something that happens in Gravity, leave out spoilers, for the sake of people like me who have yet to see it. Only mention things that you've seen in the trailers, thanks! ). What doesn't seem to get much talk, at least on the forums, is what real astronauts (and cosmonauts) could do if they found themselves "off structure".

Don't worry. This is just an old suit filled with radio equipment for an outreach program, and totally not the one crewmember who constantly had One Direction playing on max volume.

This video by Khan academy (http://youtu.be/By-ggTfeuJU) explains something that they could if they had something "massive" on their person. As they were drifting away from their spacecraft (or spacestation), they throw the object in the opposite direction from the spacecraft, and by Newton Third Law, the object exerts a force on them, hopefully strong enough to accelerate them towards a handrail.

I'm interested in whether real EVA suits have masses fitted on, so the astronaut would defiantly have something to throw.

In my opinion, the best safeguard against such an accident would've been the MMU, or Manned Maneuvering Unit.

This guy either feels very big, or very small.

Used in real life by Space Shuttle astronauts, beginning with Bruce McCandless II, and by professional space-hunk George Clooney in Gravity, this RCS pack gives the astronaut control over their trajectory relative to the spacecraft, and their own attitude.

Bruce McCandless II

The point of the MMU is to assist astronauts during EVA (It was used to reach defunct satellites without the Shuttle having to dock to them), but had obvious applications for emergencies. After the Columbia accident, however, it was grounded, replaced by SAFER, or Simplified Aid for EVA Rescue, which is designed specifically in case the astronaut became untethered.

What would people on the ground, and other crewmembers do if an astronaut was "lost", and what is your stance on what should be done, what pieces of equipment would you make use of?

Edited November 7, 2013 by Drunkrobot

[Nuke]

i dont know why all space suits dont have some kind of emergency maneuvering facility. even if its just a co2 tank and a few cold gas thrusters (a 4 thruster system would be sufficient for yaw and pitch control as well as propulsion). for more thrust perhaps use small hybrid thrusters using onboard reserve o2 (which could also be used for emergency life support), and rubber/acrylic/whatever. its unlikely you will get separated with much relative velocity, so only a few seconds of thrust would be neccisary to return to the station or whatever. key thing is its an emergency system, not intended for regular get around use.

[SargeRho]

Unless he's in an MMU, he's pretty much boned. It might be possible to use the Canadarm though.

[Canopus]

They have the SAFER: http://en.wikipedia.org/wiki/Simplified_Aid_for_EVA_Rescue

Basically a micro MMU.

Edit: I see you actually mentioned it yourself, so why ask the question?

[Nibb31]

As you have seen, NASA astronauts are equipped with SAFER. If the astronaut was incapacitated or if the SAFER mulfunctioned, the contingency plan was to manoeuver the Shuttle to catch him in the payload bay. I don't think there is such a plan with the ISS.

Edited November 7, 2013 by Nibb31

[Tarrow]

I don't think there is such a plan with the ISS.

Probably couldn't do it with the ISS as a whole but maybe doable using whatever resupply vessel is attached to it at the time?

The way I see if if you can't manoeuver something to the drifing astronaut before the life support expires (about 8.5 hours max) then all you can do is wave goodbye and notify next of kin.

Personally I'd use a self-propelled "rescue buoy" by forcing all EVA capable craft to carry what amounts to an RCS propelled low speed wire-guided missile / torpedo - that trails a high-strength monofilament line attached to a winch. Simple (70s tech), effective and reuseable. But I'm not NASA

Edited November 7, 2013 by Tarrow

[Nibb31]

Probably couldn't do it with the ISS as a whole but maybe doable using whatever resupply vessel is attached to it at the time?

It's probably not feasible to go and rescue a stranded astronaut with a Soyuz. Soyuz does have an EVA hatch on the orbital module which can be depressurized for contingency situations, but no handrails for the astronaut to hold on to. You would need a second astronaut doing a stand-up EVA from the hatch to try to catch the stranded astronaut. Even then, I'm not sure that a US EMU suit could fit through the small EVA hatch of the Soyuz, or if two suited astronauts could fit inside the Soyuz orbital module.

Neither Dragon, Dreamchaser, or CT-100 are EVA capable, so they would be useless for a rescue.

The way I see if if you can't manoeuver something to the drifing astronaut before the life support expires (about 8.5 hours max) then all you can do is wave goodbye and notify next of kin.

I don't think that would ever happen anyway. The probability of a tether breaking or an astronaut forgetting to attach it are already very slim. This is basic life-saving training that is hardwired into their brain. Then combine the probability of the SAFER failing, and the probability of drifting too far for the second astronaut (they always EVA with a partner) to catch with his own SAFER. We must be talking probabilities in the 1:1,000,000.

Personally I'd use a self-propelled "rescue buoy" by forcing all EVA capable craft to carry what amounts to an RCS propelled low speed wire-guided missile / torpedo - that trails a high-strength monofilament line attached to a winch. Simple (70s tech), effective and reuseable. But I'm not NASA

SAFER is the rescue method. No need for another one.