Conditions in Sirius

[Unseelie]

Question: If you can't lose heat in vacuume, how do things like planets get heat?
The heat doesn't come from them, it comes from the sun...I think this proves that heat -can- be radiated.

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[bluntpencil2001]

Question: If you can't lose heat in vacuume, how do things like planets get heat?
The heat doesn't come from them, it comes from the sun...I think this proves that heat -can- be radiated.

Not via conduction. Heat from people is largely conducted, not radiated.

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[AdamantineFist]

Wild West-ish, I'd say. Central house areas (think Manhattan) would be the equivalent of being on the west coast of the U.S. at the time, in a large city. Perfectly safe from hostile invaders, but you might encounter the occasional cutpurse or the like. Going into the Independent Worlds and some of the Taus, Omegas, and all the Sigmas is like the edge of civilization, prone to banditry and lawless. The Borderworlds (encompassing the near Omicrons, far Gammas, and far Taus) are way out there, full of who-knows-what, ruled by the pirate lords and generally full of nastiness. The Edge Worlds (the far Omicrons) are nearly completely unknown. Sort of like "darkest Africa" way back when, or the New World back during the time of the Vikings. No law. Nearly no people you'll be able to relate to. Hostile. Unknown. Deadly.

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[Agmen of Eladesor]

this goes against what i was taught in physics class. Space, being (mostly) a vacuum, has no molecules to bounce together to retain any heat. A glass of water, with its van-der-waals' forces and surface tension will not just turn into a mist immediately, but will lose heat through conduction, convection and radiation. there will be a process of evaporation, where the faster moving water molecules will break through the surface tension and wander off, as there is no atmospheric pressure pushing down on the surface of the liquid. this evaporation will reduce the average heat in the remaining water, which will turn to ice.

in the case of a human without a suit, there is the problem of pressure. at atmospheric pressure, our bodies are super-saturated (80%) with nitrogen, the stuff that causes the 'bends' when a diver decompresses to fast. In space, the decompression from one atmosphere to zero is immediate, and the nitrogen would boil out of your tissues, your skin and into your blood, creating air blocks in the vessels of your heart and brain - killing you instantly. the wounds caused by the nitrogen's violent departure from your body would rip your lungs to shreds, as well as your eyes, and delicate skin, such as your face. your body would leak blood into space in the same process as the water above. Estimated time of survival? less than 30 secs before death. Rescue needs to be within 10-15 secs before permanent brain/heart/lung damage.

Well - not exactly.

I figure a NASA astrophysicist would have the correct answer.

If you don't try to hold your breath, exposure to space for half a minute or so is unlikely to produce permanent injury. Holding your breath is likely to damage your lungs, something scuba divers have to watch out for when ascending, and you'll have eardrum trouble if your Eustachian tubes are badly plugged up, but theory predicts -- and animal experiments confirm -- that otherwise, exposure to vacuum causes no immediate injury. You do not explode. Your blood does not boil. You do not freeze. You do not instantly lose consciousness.

Various minor problems (sunburn, possibly "the bends", certainly some [mild, reversible, painless] swelling of skin and underlying tissue) start after ten seconds or so. At some point you lose consciousness from lack of oxygen. Injuries accumulate. After perhaps one or two minutes, you're dying. The limits are not really known.

You do not explode and your blood does not boil because of the containing effect of your skin and circulatory system. You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly. Loss of consciousness occurs only after the body has depleted the supply of oxygen in the blood. If your skin is exposed to direct sunlight without any protection from its intense ultraviolet radiation, you can get a very bad sunburn.

At NASA's Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in '65. He remained conscious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain. The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds. The subject regained consciousness at around 15,000 feet equivalent altitude. The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to boil.

Aviation Week and Space Technology (02/13/95) printed a letter by Leonard Gordon which reported another vacuum-packed anecdote:

"The experiment of exposing an unpressurized hand to near vacuum for a significant time while the pilot went about his business occurred in real life on Aug. 16, 1960. Joe Kittinger, during his ascent to 102,800 ft (19.5 miles) in an open gondola, lost pressurization of his right hand. He decided to continue the mission, and the hand became painful and useless as you would expect. However, once back to lower altitudes following his record-breaking parachute jump, the hand returned to normal."

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Oh god... The end of days... Agmen agreed with me.

[AdamantineFist]

We humans can be remarkably tough when it comes down to it, eh?

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[Agmen of Eladesor]

Apparently there HAS been an incident of exposure. Over at this site he mentions a case of a shuttle astronaut puncturing his glove. The astronaut didn't even realize it, and between his skin and the blood, it sealed the hole.

Sort of reminds me of the old Robert A. Heinlein story, "Gentlemen, Be Seated."

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Oh god... The end of days... Agmen agreed with me.

[AdamantineFist]

Apparently there HAS been an incident of exposure. Over at this site he mentions a case of a shuttle astronaut puncturing his glove. The astronaut didn't even realize it, and between his skin and the blood, it sealed the hole.

Sort of reminds me of the old Robert A. Heinlein story, "Gentlemen, Be Seated."

Of course, we have to realize that this all happens within the Earth's Magnetosphere. If we were to be outside that, then the results would be... painful, to say the least. Even the spacesuits worn by modern-day astronauts aren't designed to work out there, I think. That would require a significant amount of shielding.

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