posted
I'm writing away, science fiction. Crew on the ground, fighting, rescuing, in the rain, dramatic storm, fly away into space, wooosh!
And the something struck me. It happened in the last scene of Serenity as well. The ship flies through the rain, and then out into space.
Now space is very cold. Would the water freeze on the ship and do bad things? Or would it wash away and leave the ship untouched?
I'm kind of stumped. Its one of those little things that bug me. My sci fi is not physics heavy. The space ships fly, and they have a 'down'. Inter-stellar gates woosh you here and there. But that whole- they fly through rain, does it freeze on their ship and do bad things in space?
posted
I recently watched the When We Left Earth series on the Discovery Channel. They showed video of the outside of the rockets and shuttles as they left Earth's atmosphere. Most of the water from condensation seems to come off as the ship is accelerating up. However, when the booster rockets separate, there are sheets of frozen liquid (possibly rocket fuel) that appear to come off as well. Either way, most liquid would evaporate from the acceleration, and I doubt what was left could cause any serious problems.
[This message has been edited by philocinemas (edited August 14, 2008).]
On that note, the force needed to push a vessel to escape velocity is tremendous. Rain ceases once a vessel travels above the cloud layer, and there's still plenty of atmosphere before the ship hits the cold of space.
After that, in the void of space it's 300 degrees in the sunshine and -300 in the shade. If some particle of water managed to stay nestled into a crook of the ship, those severe temperature variations would take care of it.
posted
Well, I gather NASA used to rotate its spacecraft to keep any outer part of it from getting too warm or too cold. I remember a writeup on Apollo 13 where the ground crew (which commanded the mission) wanted the extremely tired crew to put the whole thing into something called Passive Thermal Control, on the idea that the crew might feel bad doing it now, but they will feel a whole lot worse when they try to power things up and find they can't do it.
I would assume that if there's any place where moisture could get into, it will, and getting it into space where it might boil or freeze could cause catastrophic problems. This, however, would be a problem for the early and primitive days of space travel (roughly 1957 to whenever there's regular and routine Earth-Moon passenger flights). When spacecraft have reached a level of sophistication equivalent to that of the current jumbo jets, likely the problem would have been dealt with.
(Probably the scene in "Serenity" was put there because it looked cool, without any "thinking out" of any problems.)
posted
Perhaps the whole getting into space, escape velocity, creates friction on the atmosphere, so the water, if there is any, evaporates?
That could work.
It was just one of those strange little moments that just STOPPED me mid-writing. A sever quirk of a roadblock.
But thank you for your thoughts. Didn't know about the whole hot and cold aspects of space, and the roll you can do to keep everything evenly warm and cozy. So I learnt something
posted
Well, the water, being physical, would have to go somewhere. Hot water boils and becomes a gas...room temperature water evaporates...cold water freezes and becomes a solid, ice, which will eventually evaporate by...oh, what was that term? Sublimation?
And all of that is just in an oxygen-nitrogen atmosphere at sea-level pressure...conditions elsewhere will vary considerably.
(I remember a story, name forgotten, where, on a cold high gravity planet (Jupiter?), ice was a precious gemstone.)
posted
Keep in mind that objects in space lose their heat very, very slowly. Don't fall into Hollywood's cliche that objects freeze instantaneously when exposed to space.
While space is very cold (interstellar space is, on average, only a few degrees above absolute zero), heat is diffused from object-to-object. In other words, for an object to cool, the heat has to go somewhere. In a vacuum, the heat has nowhere to go, so will only bleed away from an object slowly through the stellar medium.
The real threat to an unprotected object in space is radiation.
quote:The real threat to an unprotected object in space is radiation.
Well, there's also the pressure difference. Anything coming from the surface of the planet is designed to withstand surface pressure which is around 14 pounds per square inch.
We don't feel that pressure because our bodies are pushing back with the same amount of pressure.
But if you take anything from the surface of the planet into space unprotected, where there is nothing pushing back, and that surface object will still be pushing outward at around 14 pounds per square inch.
Water droplets will expand as pressure on them decreases until they dissipate. The phase diagram that shows sublimation, evaporation, and vaporization thresholds also shows that those thresholds depend on pressure as well as temperature.
posted
Vacuum is, of course, a good insulator. You guys have heard of Thermos bottles, right?
*****
I suppose what effect water will have on the skin of a spaceship would depend more on whether it expands or contracts at space-normal temperatures and pressures. Ice can really do a number on, say, a concrete sidewalk.
(Sidebar on expansion: I just reglued this broken piece of surfacing back onto my countertop. The glue bottle warned it would expand, and it did, past the break points and out the sides. I've been shaving it off with a razor, bit by bit...)
posted
For the record, I've heard that ice on the shuttle makes NASA nervous and has endangered launches by damaging protective materials as the water froze.
It seems your story’s universe has regular manned space travel, so the setting is in the future or another universe. You were already using non-existent technology without analysis, and most if not all of your readers will have seen spacecraft launch in rainy weather (from Serenity, Star Wars, etc.). I don’t think readers would protest. If the scene still bothers you, and you want to keep the storm, tell yourself the engineers came up with a way to minimize the effects of ice. Maybe nanobots specifically designed to dissipate water roam the surface of the craft, the craft's shell is of a strong yet flexible material that repels ice, or the craft is so streamlined that ice poses no danger.
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