David Wintle asked:
In the movie 2001 - A Space Odyssey, astronaut Dave has to reenter the mothership from his pod but he does not have his helmet. Leaving the pod without a helmet, would he freeze first (space being 2.7k), or would his lungs erupt due to relative high pressure of air in his lungs c.f. space (vacuum) or would the cosmic radiation zap him straight away, or could he make it back into the mothership?
We put this question to the team...
Andrew - So this is absolutely brilliant. Youíve got to first start how do you get in space. With a lack of a transporter there, I'm going for someone who opens the airlock whilst you're taking a nap and itís on the ISS and suddenly the pressure drops. The first thing thatís going to happen, itís a bit cold because weíve got the gas expanding again Ė we discussed earlier. You're going to also notice that the air is going which you need to breathe. So the crucial thing to do at this point is you got to remember not to hold your breath.
Kat - Thatís really hard.
Andrew - I donít think so because if you just think you need to scream, that might be quite natural.
Kat - Okay.
Andrew - Because otherwise, all the air in your chest is going to want to expand through your chest and thatís not going to be good for you.
Kat - Okay, so you would explode from your lungs. CarolineÖ
Caroline - You'd also have to be careful to not cry. Because of the lack of gravity, your tears donít fall. They just kind of accumulate on your face and can block your mouth and nose, and you could drown in your own tears.
Kat - Will they be frozen though?
Caroline - I suppose. Would they freeze?
Kat - You drown in your own frozen tears.
Andrew - Oddly, they boil and freeze. So the low pressure means they boil, but the low temperatures mean they freeze. So you get this kind of micro crystals forming.
Kat - Abrasive or sort of maybe exfoliating.
Andrew - Well, they're probably going away from you.
Kat - Adam, what do you reckon?
Adam - Well, I was going to ask, how much time are we giving ourselves here?
Andrew - Well, not very long which is very Ė the door has opened, the air is rushing out. Itís like a balloon.
Adam - Are we talking we have maybe a minute to live orÖ?
Andrew - So on the air front in 15 seconds, your brain will basically decide to protect itself and you'll be unconscious. In about 2 minutes, you'll be asphyxiated.
Adam - So, weíre not worrying about the abrasive effects on our skin of our frozen tears then because weíre going to die because itís hard to breath.
Andrew - If someone gets to you in 2 minutes and if you're outside the ship by this point, you're going to start to get sunburn quite badly. As you got high factor sun scream you';ve avoided this.
Kat - Why would you get sunburn in space? You always think of it as being like dark and cold. Why would you get sunburn?
Andrew - So on the Earth, we have the ozone layer protecting us from all the UV but you take the ozone layer when all these things protect us on the planet, and suddenly, youíve got raw sunlight on top of you. So, you're suddenly going to get a huge amount of radiation on your skin.
Kat - This always reminds me of the joke about the astronauts who wanted to go to the sun and then thought, ďWell, itís going to be really hot during the day so letís make sure we go at night.Ē
He'd die from lack of air. Cosmic rays wouldn't do much in the time we're talking about. His head wouldn't explode, his blood wouldn't boil, and he wouldn't freeze to death. He'd only harm his lungs if he tried to hold his breath. If he had to jump from one spaceship to another without a spacesuit, he'd be OK provided he wasn't in space for too long. This article gives some details: