Say some astronauts took off in a rocket and headed straight for the sun. How many miles from the sun would they be before they actually burned up? Would they die (from radiation or whatnot) before they burned up?
Assuming they didn’t run out of fuel and end up merelt in orbit around it, you mean? (it’s actually quite hard for an object in orbit around something (like us, around the sun) to leave that orbit; you’d have to actually slow down from the earth’s orbital velocity to a standstill and fall into the sun.
As to your actual question, I haven’t a clue, except that by the time you reach the orbit of Mercury, you’d be pretty uncomfy.
Let’s assume that there is a way to leave earth’s orbit, and head straight for the sun. I would guess that it’s a big enough target that you can’t miss.
From a bit of quick research, I can tell you your first problem is heat. While the surface of the sun is a balmy 5800 Kelvin (9980 deg F, or 5527 deg C), the corona reaches 1 million Kelvin (1.8M deg F, or 999,726 deg C) This is enough to pretty well vaporise anything on the table of elements.
That said, they are sending a probe to Mercury to orbit it in 2009. It will rest behind a sunshield made of the same stuff the shuttle’s heat sheilds are made of. And it won’t be in a orbit that will leave it in the sun long enough to fry it.
It might be possible, but it’d be fun to watch.
The corona has plenty of temperature, but precious little heat. It’s at a few million degrees, but the material there is so diffuse that you’d still freeze to death before you’d cook.
How close you could get would depend on your spacecraft. The “surface” of the Sun (the photosphere, or the part you can see) is at the exact same temperature as anything else that’s glowing yellow-hot, and there’s plenty of materials which can withstand even blue-hot temperatures, for a while, at least.
By the way, it really is very easy to miss the Sun. All of the planets do it all the time. Yes, it’s big, but it’s also far away.
It really is impossible to hit the sun just by turning on your rocket and pointing at the sun. The thing is, you’ve got a huge sideways vector if you are orbiting the Sun along with the Earth.
Why doesn’t the Earth fall into the Sun? Well, it’s trying, the Sun’s gravity pulls it in, but its sideways velocity is exactly equal the the Sun’s gravitational force.
So, if you are sitting there in a rocket you aren’t sitting still, you are orbiting the sun. If you point your rocket at the sun, you haven’t killed that sideways component of your vector, so what you’ll really do is put yourself in an elliptical orbit around the sun.
The only way to head straight for the sun is to point your rocket in the direction opposite earth’s rotation and fire. Unfortunately that will take a huge amount of energy. The most energy efficient way to send yourself to the sun is to put yourself into an eliptical orbit, the outer part being earth orbit and the inner part inside the radius of the sun. That’s still going to take quite a bit of energy, so probably you’re going to want to use the other planets to slingshot and lose orbital velocity. That’s going to take some time, but at least you won’t run out of rocket fuel.
See, that’s the trouble with rockets…they are limited by how much reaction mass they can carry. Without going to the bother of doing the calculations, I bet we couldn’t build a rocket with enough delta-v to hit the sun without the planetary slingshot trick.
Now, Chronos, I doubt they’d freeze in the corona, since they wouldn’t be able to radiate heat out. They might not pick up much heat from the exterior since it’s still pretty much vacuum, but their internally generated heat would cook them pretty quickly. They won’t be able to radiate all that heat out into the universe.