I know the sun has no solid surface and is to hot to try and land anything there, but hypothetically, if some kind of unmanned craft were shot directly at the sun, could it reach it or would solar winds or some other factor repel it or blow it back out into space? Or would it burn up before any of that happened?
You didn’t give any details about the nature of your spacecraft. So I’m going to assume it has the characteristics of a tungsten countertop.
Of course it could reach it. Plenty of stuff crashes into the sun – comets and various small asteroids, for one. Reaching it in the same form it left home base is quite another story, of course. It would obviously be extremely difficult for it to reach the Sun in, for example, the solid state, given the staggering amount of energy the Sun emits. One possibility would be to go for a very rapid flyby, an orbit with a perihelion very close to the radius of the Sun and a godawful velocity. If you don’t stay near the surface of the Sun very long, the amount of energy you absorb can be reduced.
I can think of three forces that would push you away from the Sun. The first two, the solar wind and radiation pressure, are small. If my calculations are correct, the solar wind generates a pressure of about 3 x 10^-5 Pa at the surface of the Sun, and radiation pressure about 0.4 Pa. The third is the ablative rocket effect. The radiation from the Sun will boil off the material on the Sunward side of your craft, creating, in effect, a rocket blast pointing at the Sun. It’s a lot harder to estimate that, the biggest unknown being the effective exhaust velocity of the material exploding off the Sunward side of your spacecraft, but if we assume it’s a modest 10 km/s we get a pressure of about 100 kPa. None of these are anywhere near sufficient to stop you falling into the Sun, if you otherwise lack the orbital velocity not to, which is no surprise, given that natural objects do fall into the Sun.
One thing to note is that it is very difficult to fire things directly at the sun. Whatever we launch from earth has a very large tangential velocity relative to the sun.
The way to do it is to slingshot round a planet or two.
Another suggestion I’ve seen in the past is to encase your probe in a sacrificial outer layer of ice. The ice boils away and takes the heat along with it, giving your probe the ability to stay cool long enough to get up close before it is uncovered. Then it has the time to perform some actual up-close observations of the Sun before it overheats and stops working.
You could as I recall use that technique to send a probe actually inside the Sun if you used enough ice for shielding; the problem being how you get any information such a probe gathers back out.
Driver8: cool site! Bookmarked.
Others: thanks! This stuff has always fascinated me. I took Astronomy as an elective in college but didn’t do well. It was far more physics than this biz major was prepared for.
Actually, almost nothing in a natural orbit will fall into the Sun. The reason for that is that everything that could already has, and everything that hasn’t before has too much energy to not fall right around the Sun. From Earth, the Sun is literally almost the hardest visible location to reach from an energy standpoint, provided you don’t care about time it takes to get there.
Wormhole; can be used both for communication and cooling. Now you just have to figure out how to construct one and keep it stable. Good luck with htat.
Stranger
Given there have been sensible scientific answers, please forgive my humour…
go up at night :smack:
Close, but incomplete. Ever touched a light bulb just after turning it off? Still hot enough to give you a nasty burn. One has to let it cool a bit first. The correct answer is to get there about an hour before dawn.
A very small percentage of solar system objects will fall into the Sun, but that still leaves a fairly large number in absolute terms. The SOHO spacecraft, which observes the Sun, has discovered more comets than any other astronomer or instrument in history, and most of those were impactors.
And depending on your definition of “inside the Sun”, we’ve already done it. The Sun doesn’t actually have a completely distinct surface: It just gets less and less dense as you go up. But the diffuse corona can be considered part of the Sun, and the solar wind can be considered part of the corona: By extension, then, anything in the solar wind is inside the Sun.