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Astronauts Pull Off Risky Spacewalk
dylanduck writes "A pair of NASA astronauts overcame an issue with a loose jet pack to make crucial repairs to the International Space Station, according to a story on New Scientist Space. No jet pack means not getting home if you inadvertently push yourself away from the space station and into space. That's a long goodbye that doesn't bear thinking about."
I jumped in and actually read this article because I couldn't bear not knowing if they had actually used duck tape to strap the jetpack to the astronaut. The sad fact is that they did not and NASA insists that it was in no danger of actually coming free... just a couple latches on the sides had come loose and the pack was both tethered to the astronaut and relatched while the astronauts were still in space actively pursuing their mission.
Gravity Sucks
It really doesn't matter what way you push off - down or 'back' (oppostite orbital direction), you end up going lower & slower, up or 'forward', higher & faster. You're still screwed, either way, but it won't be quick. (Well, unless you pop the suit open. That's quick.)
Have you been touched by his noodly appendage?
All astronauts are tethered to the station on spacewalks, there was never any risk. This is just stupid sensationalism, as usual.
How we know is more important than what we know.
Right. This is why each participant in the EVA is attached to 2 thethers at all times. Either 50' or 85', depending on where they are and where they're going.
The backpack is a tritary backup in case both tethers are released.
The item they are referring to is the SAFER (Simplified Aid For EVA Rescue) backpack.
SAFER is not an integral part of the EMU, rather it is a derivative of the MMU which is exclusively for emergency (loss of tether) use.
SAFER can provide an adrift astronaut with about 10m/s Delta-V ie: If you're travelling away from the station at less than 10m/s you have a chance of getting back (although the closer you are to 10m/s the longer it takes to get back)
Ripping an new rectum in the fabric of spacetime.
Or rather tethers.
Whenever the Astronauts are on EVA, they keep themselves tethered to either the station, the shuttle or a hardpoint on a robotic arm.
The 'SAFER' backpack in question is strictly for emergency use should the worst happen and an astronaut go adrift. SAFER is normally only employed when there is no vehicle readily available to effect a rescue (ie the Shuttle is docked so it cannot persue a drifting astronaut in a hurry).
Ripping an new rectum in the fabric of spacetime.
Here's your answer (for what's it's worth, I work for NASA).
The shuttle airlock is in the cargo bay at the base of the docking system. It's literally the tunnel between the vehicles. In order to go out the shuttle airlock, the hatches must be closed between the vehicles and both crews have to go back to their "home" spacecraft (since otherwise they'd be isolated from their rides home). Obviously we don't want the entire shuttle crew hanging out all day in the orbiter when there is work to do on ISS. Additionally, the folks doing most of the robotic arm work in ISS are actually shuttle crew members (since they can be trained on flight specific tasks very close to the mission) and they need to be able to go between the vehicles.
Quest doesn't suffer from this problem since it's hanging off the side. Additionally, depressurizing the shuttle airlock sometime introduces some control system challenges because it loses it's rigidity somewhat and it's part of the structural backbone of the vehicle, so that's nice to avoid.
That being said, the capability remains to go out the shuttle airlock if need be.
Worst...sig...ever!
In theory you could move the space station, in practice you could not. The space station isn't really designed to be maneuvered in real time by the crew (or the ground, for that matter). Attitude maneuvers can be accomplished fairly quickly (less than an hour if you really had to), but translational maneuvers (which would be required to go grab an astronaut) take in excess of a day to put together and execute. Space station normally bores holes in the sky, so it that capability was never designed in (like it was on the orbiter or Soyuz). The orbiter can't undock quickly enough to go get them, either - at least not without compromising the safety of the rest of the crew and the vehicles themselves.
Which is the whole reason why SAFER was developed. Back in the shuttle-only days, going and grabbing the lost crew member on a double tether failure was a viable option, today it isn't.
Worst...sig...ever!
If you slowly push away from the space station, you won't keep moving away from it in a straight line, because you and the space station are both orbiting the earth. In 46 minutes or so you may find yourself passing by it again.
:)
The parent actually has an interesting point but is simply bad at explaining himself, stop modding him down
1) The height of one's orbit is directly related to the speed - the higher the speed, the higher your orbit
2) If you push yourself away so that your earth-relative speed changes (e.g. forward or backward), you will get to a higher or lower orbit, and cannot get back to the station
3) However, if your earth-relative speed doesn't change (e.g. if you push yourself off perpendicularly), you will keep orbiting the Earth at the same height as before. So we'll have two orbits (ISS and you) with
a) same height and speed
b) slightly different angles
c) you were at the same point at some point in time
These orbits will keep intersecting in two points, the original point, and one right across the Earth, so it's actually possible to get back.
When men used to be men
The jet pack is great, but the astronauts don't put their lives entirely on them. Actually, what really make the EVA safe are two tethers, linking the astronauts to the ISS. The issue with the jet pack was that the danger of it becoming space debris, what could put the ISS in danger. Check it out at space.com or any really serious space news site.