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A Real Sun Probe, Take the Solar Plunge
Guest_Richard Trigaux_*
post Dec 29 2005, 05:53 PM
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QUOTE (BruceMoomaw @ Dec 29 2005, 04:38 PM)
...I later learned that NASA was actually shutting up any engineer or scientist from publicly proposing an economically designed Pluto mission by threatening to cut off their grants... 


I hate this way to shut down any debate or new idea. There was another example about the technician who tried to warn about the hole into the shuttle heat shield... He was not heeded, with the result we know. Worse, in place of recognizing their mistake, the responsibles humiliated him in asking him to retract his view in public.

Ideas come at no cost, and they can make huge savings. So it is really a shame not to examine a given idea. And it is definitively not a shame if we are not the author of a good idea.
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lyford
post Dec 29 2005, 06:29 PM
Post #32


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QUOTE (Bob Shaw @ Dec 29 2005, 08:45 AM)
Bruce:

Careful there Ted, or Crazy Dan might try to pull strings to have you nominated as the command pilot of a (briefly) manned Solar mission!

Of course, he'd stand every chance of getting the second seat reservation for himself...

...I wonder who'd get the third slot?

Bob Shaw
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Perhaps Hotblack Desiato?


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Lyford Rome
"Zis is not nuts, zis is super-nuts!" Mathematician Richard Courant on viewing an Orion test
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tty
post Dec 29 2005, 06:38 PM
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QUOTE (kwan3217 @ Dec 29 2005, 07:05 AM)
1) Carry a large supply of carbon, and pump it out of the surface of your platform. The carbon vaporizes and carries off the heat. Use carbon since it has the highest known melting and vaporization temperature of any substance. It acts like an ablative heat shield, or as the story described it, the bottom layer of a water drop in a hot pan.
*



I wonder if the use of coal to absorb the heat has something to with an idea Freeman Dyson came up with when he was working on the Orion nuclear propulsion project. The problem was how to test the concept without breaking the test ban since the test needed to be done in vacuum.
Dyson’s idea was to do the test indoors in a very large vacuum chamber. This would be partly filled with hundreds of tons of charcoal blocks suspended on wires. The explosion would of course turn the charcoal into fine dust which would then absorb the energy from the explosion by being converted into gas. The pressure wouldn’t be excessive since most of the volume was originally vacuum and the energy would transfer relatively slowly to the chamber walls so they wouldn’t melt, at least not much. According to Dyson’s calculations the whole thing would only work for quite small nuclear explosions, up to a few tenths of a kiloton, but that was the range they were interested in for the Orion project anyway.

The idea apparently interested the AEC as well when they realized that if done in an underground cavity it would both prevent the escape of nuclear debris to the atmosphere and almost completely de-couple the explosion from the surrounding rock, thus making it possible to do undetectable nuclear tests. According to rumour it was actually tried in extreme secrecy in Nevada and worked more or less as intended. blink.gif

tty
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punkboi
post Jan 6 2006, 05:51 PM
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QUOTE (Richard Trigaux @ Dec 26 2005, 02:27 AM)
Not yet any Bush plan for Sun colonization?
*


Hahaha!! I'd say something...but I don't wanna turn this into a political topic.

EDIT: Okay, so I just browsed through the rest of this thread. I guess I didn't have to get political. tongue.gif


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Bob Shaw
post Jan 6 2006, 11:06 PM
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QUOTE (tty @ Dec 29 2005, 07:38 PM)
I wonder if the use of coal to absorb the heat has something to with an idea Freeman Dyson came up with when he was working on the Orion nuclear propulsion project. The problem was how to test the concept without breaking the test ban since the test needed to be done in vacuum.
Dyson’s idea was to do the test indoors in a very large vacuum chamber. This would be partly filled with hundreds of tons of charcoal blocks suspended on wires. The explosion would of course turn the charcoal into fine dust which would then absorb the energy from the explosion by being converted into gas.  The pressure wouldn’t be excessive since most of the volume was originally vacuum and the energy would transfer relatively slowly to the chamber walls so they wouldn’t melt, at least not much. According to Dyson’s calculations the whole thing would only work for quite small nuclear explosions, up to a few tenths of a kiloton, but that was the range they were interested in for the Orion project anyway.

The idea apparently interested the AEC as well when they realized that if done in an underground cavity it would both prevent the escape of nuclear debris to the atmosphere and almost completely de-couple the explosion from the surrounding rock, thus making it possible to do undetectable nuclear tests. According to rumour it was actually tried in extreme secrecy in Nevada and worked more or less as intended. blink.gif

tty
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Freeman Dyson = Total JOY!

What a guy!

Bob Shaw


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Remember: Time Flies like the wind - but Fruit Flies like bananas!
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ljk4-1
post Jan 7 2006, 03:02 AM
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QUOTE (Bob Shaw @ Jan 6 2006, 06:06 PM)
Freeman Dyson = Total JOY!

What a guy!

Bob Shaw
*


He is also pretty nifty at coming up with ways to utilize all of a star's energy:

http://www.orionsarm.com/civ/Dyson_Spheres.html


--------------------
"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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PhilHorzempa
post Jul 6 2007, 02:49 PM
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The Solar Probe project is still alive. In a Report released on July 4, 2007,
regarding their actions on NASA's FY 2008 budget, the Senate
Appropriations Committee states the following - "The Committee
has included an additional $20,000,000 for the Living With A Star Program
for the Solar Probe mission."



Another Phil
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Pando
post Jul 9 2007, 06:41 AM
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http://solarprobe.gsfc.nasa.gov/
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tedstryk
post Jul 19 2007, 05:41 PM
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If it actually gets funded, it should also give us a nice Jupiter bonus. I am not sure about imaging (perhaps it will have a navigation camera or be able to catch Jupiter and its moons in one of its cameras intended for the sun like STEREO did), but I can't imagine them passing up the chance to at least have a Ulysses-style encounter, given the fact that this mission will certainly have its fair share of particle and fields instruments.


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Y Bar Ranch
post Jul 29 2007, 11:01 PM
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Hey, my first post here.

So my idea for a solar probe involves a super long tethered probe, spinning at a rate so as to have it's surface velocity with respect to the Sun be close to zero. The "mothership" would be far enough away to endure the environment. I know, extremely long tether...

Another thought I had would be a "floater", i.e., a probe with enough surface area that it took advantage of the flux of light and other stuff to suspend itself at a distance above the surface. It'd be a way of lowering the geosynchronous orbit altitude way down, or generally lowering the speed of the orbit. I didn't see any other concepts taking advantage of solar sails to assist in reaching the Sun.

Maybe the floater and the tether could be combined.
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Guest_Geographer_*
post Nov 8 2007, 04:18 PM
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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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JRehling
post Dec 11 2007, 08:23 AM
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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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ngunn
post Dec 11 2007, 11:42 AM
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Has anyone suggested using the phenomenon of total internal reflection in glass prisms? This is virtually 100 percent efficient.
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ugordan
post Dec 11 2007, 11:49 AM
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Wouldn't a big glass prism be massive?


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ngunn
post Dec 11 2007, 11:57 AM
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Lots of little ones forming a scaly skin? A cloud of detached beads in front of the spacecraft??

I dunno, just rambling. smile.gif
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