Parker Solar Probe, Take the Solar Plunge |
Parker Solar Probe, Take the Solar Plunge |
Dec 25 2005, 12:33 AM
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Senior Member Group: Members Posts: 2454 Joined: 8-July 05 From: NGC 5907 Member No.: 430 |
Any serious plans to send a probe into the Sun to explore its depths as far as possible?
What would help a probe last as long as it could and how deep could it get? Could it even radio or laser out any data? What about a Sun skimmer? -------------------- "After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance. I see that such intercourse long continued would make one thoroughly prosaic, hard, and coarse. But the longest intercourse with Nature, though in her rudest moods, does not thus harden and make coarse. A hard, sensible man whom we liken to a rock is indeed much harder than a rock. From hard, coarse, insensible men with whom I have no sympathy, I go to commune with the rocks, whose hearts are comparatively soft." - Henry David Thoreau, November 15, 1853 |
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Guest_Geographer_* |
Nov 8 2007, 04:18 PM
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Guests |
What is the highest level of albedo that's been achieved with metals on Earth? If a shield had 100% reflectivity (impossible I know but theoretically), would that solve all heating problems, or does the albedo vary for different types of electromagnetic radiation?
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Dec 11 2007, 08:23 AM
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
From one reference on the web, I'm seeing that aluminum has an albedo of 73%.
Suppose that tungsten had the same albedo. By my calculations, a surface of tungsten, then, would melt if held in steady state at about 0.17 AU. However, there are a lot of other tricks that could be played to help out. A thin foil of tungsten would only take solar radiation on one side while radiating it on the other. Halving the thermal load should allow an approach sqrt(2) closer. The sunscreen on SP is a long cone that would be pointed towards the Sun. That spreads out the radiation that a disk would absorb over a much greater area. I don't see any theoretical limit to this approach, although the point at the very tip might be a failure point. There would have to be SOME surface perpendicular to the Sun. I guess if a maniacal plunge sunward were attempted with the goal of approaching as near as possible, one strategy would be to have a series of sunscreens, each of which had enough separation from the main craft so as not to radiate much heat inward, with each one shaded until the one in front of it melted through. If the final plunge were fast enough (if, say, a gravity assist of Jupiter really whipped the thing into the Sun, with all of the acceleration that would come with that last neck of the Sun's gravity well), it might make a lot of progress in those final hours during which the screens were melting one after another. I wonder what the engineering limit would be. The corona? The point where gas actually contributed measurable friction? Since such a craft could easily be set up for a free return to Earth, could we run a solar sample return?!? I'm not sure if there's much point doing it from close-up versus collecting the solar wind farther out, but it's an exciting idea. |
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