Are there warm places in space?
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freyar
Extradimensional Explorer
In fact, you'd rather the sail surface be reflective (white, for example) than absorptive (black). If the light reflects (bounces back) off the sail, it gives more forward momentum to the ship.This would work, but it's not necessary to have the facing surface black. Solar sails can be made from simple mylar.
Solar sail - Wikipedia, the free encyclopedia
The solar sail has appeared in scifi literature, too. The Mote In God's Eye features a laser-powered one fairly prominently in the beginning.
Okay, I don't know a lot about temperatures in outer space, but I did stay at a Holiday Inn Express last night...
Yes. Note that this is not the same as the radiometer. The radiometer uses the flow of a rarified gas to move the propeller. A solar sail uses pressure from light (and/or solar wind) to move it around. Much different mechanism.
Theo R Cwithin
I cast "Baconstorm!"
Emphasizing this.
@Bullgrit: The radiometer is a very different sort of effect, requiring a small amount of air-- so it won't work in space.
IMHO, the solar sail is much more intuitive, and works basically like a an ordinary sailboat sail-- except it works by catching and reflecting light (mainly) from the sun, rather than catching and "reflecting" wind.
In fact, I think this is exactly the effect you were originally thinking of when you were looking at that radiometer in the store and getting confused about why it was rotating backwards to your intuition!
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Merkuri
Explorer
Regarding solar sails, there's an episode of the (newer) Outer Limits that I saw on Hulu a little while ago that involved an alien craft powered by solar sails that had gone off course and was aimed to hit something in our solar system (either the earth or the sun, I forget which) and they tried to contact somebody on modern-day earth so they could build a laser and push the solar sail craft into a new course to avoid the collision.
I've seen other scifi shows with solar sails, too. I seem to recall some sort of ancient craft on DS9 had solar sails.
I've seen other scifi shows with solar sails, too. I seem to recall some sort of ancient craft on DS9 had solar sails.
freyar
Extradimensional Explorer
You know, I forgot to respond to this part before. The main effect that's been noticed is on the even older Pioneer probes (though I believe I may have seen something similar about the Voyager probes). It's actually called the Pioneer anomaly because it has been unclear if the deviation of the space probes from their expected path could be explained by astrophysical effects like solar radiation, etc. There have been some pretty far out explanations proposed, actually. However, I think there's been some convergence over the last few years that radiation pressure, particles in space, etc, can actually explain this measurement. I haven't followed it all that carefully, though, just reading abstracts, so maybe someone knows more than I about this.
a bunch of interesting bits here to consider.
If we build a "unprotected space walk" test lab in the dark side of the moon, what would happen?
I'm thinking naked guy with a good breathing mask.
Dark side of the moon, to block the sun's rays (no heat source or deadly radiation source).
If we have to, further imagine the walk will take place in a "glass vacuum tube" that blocks bad radiation, but isn't 'airtight'). So our vacuum tube isn't air tight, it's filled with whatever space is filled with.
Our walker is to carefully decompress and then proceed out the lock and through the space-tube.
Will his body temperature drop? Will his heat radiate off of him into space (thus lowering his temperature).
I think it would not be accurate to assume that heat only transfers through materials (air, metal), since it seems to transfer from the sun to the earth with no transmitting matter.
One complication to the experiment is that decompressing something causes it to cool. I'm not sure how slow you could go and not have that effect.
Would the experiment be more valid with a toaster? Basically something that sits in the space-tube of isolation, heats to a temperature, and then stops heating itself. Does the object cool in space, and if so, over what period of time does it go from too hot to "ok to take the toast out"?
with the toaster example, i think the question really is to get an idea is to compare it to a toaster cooling off in my kitchen. Which is kind of what the OP was hinting at.
On the solar sail thing, the question is, does it really work? Have we launched one to prove it? The radiometer, as somebody mentioned is demonstrating a different effect because of the gas, and is not a solar sail effect.
As for white or black sails, I'm not sure absorbtion into the material (per black) would make sense. If you have a mini sailboat, pushing your finger into the sail propels the boat. It isn't absorbed into it. If the sail were BB proof, shootng the sail from the right angle with a BB gun would propel the ship forward. The BB would bounce, but the ship would move.
A sailing ship sail isn't fully impermeable, some air would pass through, some is deflected at an angle, some loses energy, and some continues "chasing" the ship as the wind and the ship go the same direction.
I'm not a physics guy, so there may be more rules to it that allow a solar sail to work and to determine the nature of it.
If we build a "unprotected space walk" test lab in the dark side of the moon, what would happen?
I'm thinking naked guy with a good breathing mask.
Dark side of the moon, to block the sun's rays (no heat source or deadly radiation source).
If we have to, further imagine the walk will take place in a "glass vacuum tube" that blocks bad radiation, but isn't 'airtight'). So our vacuum tube isn't air tight, it's filled with whatever space is filled with.
Our walker is to carefully decompress and then proceed out the lock and through the space-tube.
Will his body temperature drop? Will his heat radiate off of him into space (thus lowering his temperature).
I think it would not be accurate to assume that heat only transfers through materials (air, metal), since it seems to transfer from the sun to the earth with no transmitting matter.
One complication to the experiment is that decompressing something causes it to cool. I'm not sure how slow you could go and not have that effect.
Would the experiment be more valid with a toaster? Basically something that sits in the space-tube of isolation, heats to a temperature, and then stops heating itself. Does the object cool in space, and if so, over what period of time does it go from too hot to "ok to take the toast out"?
with the toaster example, i think the question really is to get an idea is to compare it to a toaster cooling off in my kitchen. Which is kind of what the OP was hinting at.
On the solar sail thing, the question is, does it really work? Have we launched one to prove it? The radiometer, as somebody mentioned is demonstrating a different effect because of the gas, and is not a solar sail effect.
As for white or black sails, I'm not sure absorbtion into the material (per black) would make sense. If you have a mini sailboat, pushing your finger into the sail propels the boat. It isn't absorbed into it. If the sail were BB proof, shootng the sail from the right angle with a BB gun would propel the ship forward. The BB would bounce, but the ship would move.
A sailing ship sail isn't fully impermeable, some air would pass through, some is deflected at an angle, some loses energy, and some continues "chasing" the ship as the wind and the ship go the same direction.
I'm not a physics guy, so there may be more rules to it that allow a solar sail to work and to determine the nature of it.
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