Lost in Space

Factual Questions
1

If an astronaut ever broke loose while taking a space-walk, how would NASA recover him/her? Are there contingency plans? The space shuttle doesn’t seem all that manoeuverable in space.

What would happen to a person, stuck in a space-suit, drifting off into space? I mean, obviously they would die as soon as the air ran out . . . but would the body ever decompose? And how about if a space mask ever cracked (hit by space flotsam or whatever) . . . what happens to human flesh and blood once exposed to space vacuum?

2

I remember reading about this when they did the first test of the jet backpack in space. This was the first time that a human has ever floated untethered from a spaceship.

At that time, they said that if the test failed and the astronaut could not return to the ship, that they could scootch the shuttle over and get him. This isn’t too much of a surprise, I suppose, since they routinely have to bring the shuttle right up next to free-floating objects for various reasons.

3

If somone went bouncing off due to a malfunctioning MMU or other accident there probably would not be any way to make a rescue.

A body exposed to space would probably dessicate pretty quickly and be mummified rather than decompose. A vacuum is very effective at drawing out moisture. A dead astronaut sealed in a space suit would probably decompose due to the bacteria already in and on the body.

4

If an astronaut broke loose during a spacewalk he or she is screwed. I’m sure NASA would try and figure a way to rescue the astronaut but I think the chances would be mighty slim for a recovery.

The body would be deep frozen after the suit ran out of power to keep the occupant warm. I imagine the astronaut would be nicely mumified and would ever so slowly evaporate over time.

If you rupture your space suit your blood will boil. As pressure is lowered the boiling point of a liquid is likewise lowered (you sometimes see alternate directions on food packages to cook longer if you live above 6,000 feet or so). It is possible to lower the boiling point of water to below freezing (32 F). Your blood, being around 98-99 degrees would boil, you’d inflate and eventually pop or rupture. Not a pleasant way to go I’d imagine.

5

<bzzt> That’s a common urban legend with no basis in truth, as I recall. It assumes that the pressure inside your body will be equalized with the pressure outside your body–which simply doesn’t happen, as your body is too solid for that sort of thing. Were there anything to breathe, you’d be unable to draw in a breath, and your lungs will empty rapidly. Your eyes would almost immediately vacuum-freeze, as would other mucous membranes. Other than that, you suffocate within a couple of minutes and then dessicate.

Only highly porous objects, or very stretchy hollow ones, expand/burst under a vacuum. This includes balloons and marshmallows, but not humans beings.

(For the record, at the top of Mt. Everest, the air pressure is low enough that the vapor pressure of water is near body temperature. Blood does not boil there.)

LL

6

If you were thrown into the vacuum of space with no space suit, would you explode?

7

Um, the pressure isn’t THAT low on top of Everest. I heard the boiling point was around 170 F, far above body temperature.

You are right about the body not exploding, though. If exposed to vacuum the contents of your digestive system would be sucked out both ends and there would be bleeding from some of the weaker points in your body, but your skin would hold, and your eyes would remain in your head.

8

Let me reiterate what Lazarus said, and give a reference: http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970603.html

Summarry: while your blood will not boil, moisture on the surface of your skin, eyes, tongue, etc., will. Holding your breath will damage your lungs, but breathing out will leave you with no serious damage for up to 90 seconds in a vacuum, though you’ll probably pass out after 10-15 seconds. You’ll have a full-body hickey, though. Ouch.

9

Ahem Spacewalk question? Somebody ask a spacewalk question?

For the Shuttle, assuming the safety tethers broke and the astronaut was sent floating away, it would be really easy for the pilot to give a little thrust and chase after him. A little orbital dynamics comes into play, but it shouldn’t be too difficult - I’m having trouble conceiving of a situation where the astronaut pushes off enough to escape the shuttle. Oh, incidently, the pilot or commander is always on duty during spacewalks.

ISS will be a different story, because without the Shuttle there, it cannot go chasing down lost crew. So they devised this nifty little emergency jet pack called the SAFER. I hooks onto the suit back below the backpack part. In the event of a tethering mishap (actually, double tether mishap), and the crew member is dislodged, he can easily activate the release for the control mechanism (a joystick), and then resume control with the SAFER. It is designed to stabilize tumbling and provide thrust to get back to structure.

Assuming we have a really bad day, and the tethering fails, and the SAFER disintegrates, so the crew member cannot get back. And assume the other crew member cannot attempt a rescue with his SAFER. And assume NASA then doesn’t pull out the Emergency Return Vehicle (CRV or Soyuz) and attempt a rescue. He floats off, runs out of air and battery power, gets cold and either suffocates or freezes - probably suffocates first. Then he will stay in orbit for a while till finally doing an uncontrolled reentry, barring NASA devising a retrieval to return the body home.

What about suit penetration? Understand the helmet actually has 2 layers to the mask, so even if hit, the first layer cracks, the second will most probably remain intact. The rest of the suit is designed with several layers of material, from the nomex outer covering through several layers of mylar insulation down to the inner bladder layer. (Not including the liquid cooling garment, as it does not seal the pressure.) The suits are designed to withstand a fair amount of penetration. Assuming a micrometeoroid punctured through all the layers and opened a hole, the suits have an emergency reserve of air to handle a fair sized leak, and the crew would rush back into the airlock.

Assuming the hole is a little bigger, then he has to worry about blood loss (from the penetration of the MMOD), and freezing, and running out of air.

NASA has never had this situation occur (even the lesser situations above), but I believe the Russians have experienced an on-orbit loss of pressure on a suit. The Orlans (Russian suits) have inner bladder layers that separate the extremeties in just such a situation, so it closes off say the arm to contain the rest of the body in pressure, but the U.S. suits do not have that precaution.

Suffice it to say, mealypotaotes, NASA has put a lot of thought into these situations, and has devoted a lot of attention to understanding the probabilities of occurrence, and how to prevent or minimize those probabilities, and how to safely deal with the problems. There is some risk, but it is very low.

10

In one of Heinlein’s stories, a lunar Scoutmaster is quizzing one of his Scouts on first aid and safety procedures on the Moon:
“And what do you do for a man with a crack in his helmet?”
“Why, you bury him, Sir.”

In the event of a tether snapping, the astronaut probably won’t go “floating off into space”, anyway. Velocity relative to the Shuttle/Space Station is likely to be very low, to begin with, and there’s no reason for it to increase.

By the way, Irishman, you didn’t mention, but I’m assuming that the maximum thrust produced by a SAFER unit is well below the ultimate tensile strength of a tether (by, say, a factor of ten)? I presume that one of NASA’s safety engineers was paranoid enough to think of that…

11

FYI, those special cooking instructions are used above about 3500 ft.

12

Chronos’ response brought to mind a story, IIRC, by Arthur C. Clarke, wherein an emergency transfer of personnel (a class of student astronaughts, I believe) had to be made from one transport to another. About twenty men had to be moved, and it appeared the fastest it could take place was about 1.5 to 2 minutes. The instructor of the class took them through hyperventilation, and also quieted their fears of immediate explosion or swelling/bursting. As I recall, in the story, the transfer was made successfully except for one student who panicked at the last moment and had to be shut out of the airlock. Anyone else remember this one?

13

No, Dennis, but in 2001 Dave had to get himself to an emergency O[sub]2[/sub] tent after HAL let the air out of the ship. A few seconds of hard vacuum didn’t seem to harm him. :slight_smile:

14

Was that Nothing Ever Happens on the Moon?

LL <-- who oughta know Heinlein

15

Chronos said:

I think the fear is that the push that lead to the break would be enough to send them moving slowly away. Of course the joys of orbital mechanics means that he isn’t likely to completely disappear anytime soon. More likely to separate, then come close to returning close, followed by more separation, and a cyclical pattern of separation. Sort of like any orbital maneuver. Technically to get away from any accidental drop of debris they have to make two burns, in orthogonal axes, to make sure they get good separation.

Paranoid… not sure that’s the best word, but it works. Yes, NASA engineers are supposed to consider all the possible safety concerns, and evaluate them, and address them to the best of their ability. And there’s multiple reviews, including a special Safety Panel that independently analyzes the failure modes. And yes, the SAFER thrust is very low and much lower than the tether strength. Fact is right now the cables are stronger than they “need to be” because of a particular combination of finding lightweight materials. There are twisted steel cables, and non-metalics. We did use Kevlar, but now use Vectran - it is stronger and has better stability in atomic oxygen and UV.

Side note: there was some concern about testing the SAFER with the crew tethered to the shuttle, they were afraid there might be a tetherball effect.

Side note 2: anybody catch the fun on STS-88 - the Node 1 (Unity Module) installation to Zarya? There were some tethering problems on that flight - including loss of a few tools and a particularly stunning demonstration of orbital gymnastics by one of the crew members. It was handled very well by the people in MCC - if you didn’t see it, you didn’t know there was a problem.

SN 3: That was one of the things that bothered me about that TV show “The Cape” - the frequent use of the threat of the loss of an astronaut on orbit as a plot gimmick. They had no understanding whatsoever of the concept of tethering. There was a lot to hate about that show, but that one was particularly grievous to me.

16

[QUOTE]
*Originally posted by LazarusLong42 *
**

Actually, LL, I think it was more probably in Space Cadets.

But I’ll need overnight to make sure.

17

I’m reasonably certain that the Heinlein story in question was “Nothing Ever Happens on the Moon”. In Space Cadet, by the time the hero (don’t remember his name) sets foot on the Moon, he’s in a position to be giving that talk, not receiving it. Besides, I’m certain that the context was Boy Scouts.

I read the Clarke story, too… It seems to me that the title might have been “The Early Days”, and it was a series of short reminiscences by one of the first pioneers about the early days of spaceflight. It was a Hugo winner; you could find it in the Hugo archives, I’m sure (they’ve got to be on the Web somewhere).