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A Real Sun Probe, Take the Solar Plunge
ljk4-1
post Dec 25 2005, 12:33 AM
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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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nprev
post Dec 25 2005, 02:07 AM
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I don't know, but my best guess would be <poof!!!> before any such probe even got close to the photosphere, so I doubt that any useful data could be gathered even if it could somehow be transmitted through all that RF noise... cool.gif (need shades just to think about it!!!)


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A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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JRehling
post Dec 25 2005, 06:15 AM
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Solar Probe was supposed to come within 3 solar radii.

I suppose an elaborately shaded craft could get pretty close. A "ball" with instruments could be surrounded with a hemispherical shade with near 100% reflectance held by struts rather far from the craft. Perhaps even a hierarchical tier of such shades could perform even better.

Entering the photosphere would instantly annihilate any craft. The velocity of the craft as it hit the outer layers of gas, which would increase rapidly in pressure with depth, would be colossal -- even aside from the radiative heat.
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dvandorn
post Dec 25 2005, 07:46 AM
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Well, there's always David Brin's solution. Use a laser to *refrigerate* the probe, and to provide braking thrust against the Sun's gravity.

The idea is to drain the thermal energy into a system that powers a very powerful, very HOT laser. This would be the *only* way to use a "radiator" to shed heat into the photosphere.

A side benefit would be that such a laser would exert *significant* thrust, and it would be aimed at a target that it couldn't much hurt -- the Sun's surface.

The catch, of course, is that we really don't have the technology to build such a hot laser, or to convert the heat we can't reflect away into power for the laser. Once we develop those technologies (if we ever do), then a solar probe is more feasible...

-the other Doug


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The trouble ain't that there is too many fools, but that the lightning ain't distributed right. -Mark Twain
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Guest_Richard Trigaux_*
post Dec 25 2005, 08:24 AM
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QUOTE (JRehling @ Dec 25 2005, 06:15 AM)
Solar Probe was supposed to come within 3 solar radii.

I suppose an elaborately shaded craft could get pretty close. A "ball" with instruments could be surrounded with a hemispherical shade with near 100% reflectance held by struts rather far from the craft. Perhaps even a hierarchical tier of such shades could perform even better.

Entering the photosphere would instantly annihilate any craft. The velocity of the craft as it hit the outer layers of gas, which would increase rapidly in pressure with depth, would be colossal -- even aside from the radiative heat.
*


Yes, if we imagine a shield, the shape of a ... shield, which shadow comes up on the probe itself, in such a way that it just eclips the Sun and, seen from the probe, appears like a disk just a bit larger than the Sun (like the Moon just eclips the Sun seen from Earth) then this shield gets very hot, indeed, but, seen from the probe, it appears as a circle just a bit larger than the Sun but not so hot. The reason is that it absorbs Sun heat from one side, but it radiates its own heat on both sides. So it can provide an efficient shadowing. And a tiered structure of such shields can really efficiently cut down the heat received by the probe itself in one or two orders of magnitude.
So we can get much closer from the Sun than with any other design. The limitation is the first shield (the shield size quickly increases with the number of tiers) which must be made of very high fusion point material and be polished so what it reflects as much heat as possible without aborbing it. The only solution I see would be a very thin veil of tungsteen, polished in front and blackened with graphite at the rear. The second, third etc. tiers would be conical in shape, to increase side radiation.

Such a design would allow to get very close from the Sun, much closer than Mercury, and, if we give the shield a slightly parabolic shape, it can also be used as a high gain antenna, and contribute to overcome the very poor signal/noise ratio.

Getting closer? The capture speed near the Sun is more than 600km/s, and this figure alone is detering: even if a probe manages to cope with the radiated heat, as soon as it will enter the corona it will drag and burn. Remember: the coldest place on the Sun is 4000C (in spots) where tungsteen and graphite cannot bear much more than 3000C. So, unless there is some very new and unexpected discovery in physics, we are bound to contemplate the Sun from afar.

The laser to cool the probe? Whatever its technology, a laser produces waste heat. And, unless we find a way to get around the second principe of thermodynamics, we cannot use it to cool anything. The only way to cool a probe would be to bring a lot of water, and make it boil to regrigerate the probe for a short time, before it gets too hot. Even one hour gained at 600km/s would allow to gain two Sun radii. But, very close from the Sun, the heat is enough to boil a full swimming pool of water in some seconds...
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Guest_Richard Trigaux_*
post Dec 25 2005, 08:36 AM
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Other ways to probe the Sun would be sending a laser ray or radio beam. Unfortunately, the Sun is opaque to both. At best we can imagine passing very close to the surface (from a probe to the Earth). We can imagine to send very low radio frequencies, but I am afraid that the time constants involved would be thousands of years. (Already on Earth probing the core with radio waves would require frequencies too low to be actualy useable).


Impossible, impossible, impossible...

So why not the most impossible of all: SUN SAMPLE RETURN MISSION!!!!

Ouah nutter and nutter!!

But paradoxically it is the simplest to do, and it was even already done, with this probe, I did not remember the name, perhaps Stardust, which went in space to capture solar wind dust, and then crashed at time of return on Earth, but all the same produed useable samples of Sun composition.

But they took no measure against contamination of Earth by Sun life form... wink.gif
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nprev
post Dec 25 2005, 08:38 AM
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The only "practical" solution I can see would be to embed a probe and several layers of redundant sensors at the dead center of a rather large comet nucleus or maybe one of Saturn's smaller icy moons and deorbit the whole thing right into the Sun using a lot of ion thrusters or perhaps mass drivers, if there was enough metallic material available to use as reaction mass...

I doubt that the value of data retrieved would ever equal the investment, though, even if all the assumed supporting technologies were ever available. Remote sensing is far better in all respects!


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Jyril
post Dec 25 2005, 12:22 PM
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QUOTE (Richard Trigaux @ Dec 25 2005, 11:36 AM)
But paradoxically it is the simplest to do, and it was even already done, with this probe, I did not remember the name, perhaps Stardust, which went in space to capture solar wind dust, and then crashed at time of return on Earth, but all the same produed useable samples of Sun composition.


The Genesis mission... It was to be captured from mid-air, because a parachute landing would have been too hard. wink.gif


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Guest_Richard Trigaux_*
post Dec 25 2005, 04:02 PM
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QUOTE (Jyril @ Dec 25 2005, 12:22 PM)
The Genesis mission... It was to be captured from mid-air, because a parachute landing would have been too hard. wink.gif
*


Yes it was that. Pity the chute did not open. So the landing WAS hard. But the scientists managed to recollect most of the science data.
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tty
post Dec 25 2005, 04:37 PM
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A lot of neutrinos from the interior of the Sun is passing through Earth all the time, so all we need to see into the Sun is a good neutrino telescope. smile.gif

tty
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Guest_Richard Trigaux_*
post Dec 25 2005, 05:57 PM
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QUOTE (tty @ Dec 25 2005, 04:37 PM)
A lot of neutrinos from the interior of the Sun is passing through Earth all the time, so all we need to see into the Sun is a good neutrino telescope.  smile.gif

tty
*


We don't have a "good neutrino telescope". But what we have already learned much about the inner Sun. And about the neutrinos...


I am sorry, I usually have plenty of ideas to do things most people think impossible, but about plunging INTO the Sun, I don't have!
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Guest_BruceMoomaw_*
post Dec 25 2005, 11:23 PM
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Richard Trigaux, alas, is too optimistic about the Genesis scientists being able to retrieve "most" of their planned data. The latest news is that they will indeed be able to properly measure the amount of noble gases in the Sun, since those (except for argon-40, which is irrelevant) exist only in microscopic amounts in Earth's atmosphere and water, and so weren't affected by the crash's contamination. But that was only their third scientific priority -- the top ones were to measure the isotopic ratios of the Sun's oxygen and nitrogen (especially the former), and unfortunately those have been very badly contaminated indeed. It's questionable whether they'll be able to retrieve any meaningful results on those.

As for Solar Probe -- whose design has been modestly changed lately, without harming its total science output -- see the very informative official Web page at http://solarprobe.gsfc.nasa.gov/ . Solar scientists would absolutely love to fly this mission, but it will cost as much as a New Frontiers mission and so NASA has yet even to officially propose it. (It's even been suggested that it should be included in the New Frontiers program. But that, in turn raises the question of whether ALL competitive-proposal programs for space science -- Solar System, Mars, astronomy, magnetospheric science or what have you -- that are in the same cost range should be folded up together into a single competitive space-science proposal program, which might well make sense.)

There is no doubt at all, however, that we can make Solar Probe work -- amazingly, we already have almost all the technology we need for it. Extensive ground tests of that dunce-cap shaped carbon heat shield show that not only does it provide full protection against the heat, but it vaporizes considerably less than expected and so won't contaminate the probe's plasma measurements. The only thing that requires any additional work at this point is the design for the "plasma periscope" that would peep around the edge of the heat shield and divert a small amount of the outflowing solar plasma to the analyzers behind the shield.
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Guest_Richard Trigaux_*
post Dec 26 2005, 09:27 AM
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QUOTE (BruceMoomaw @ Dec 25 2005, 11:23 PM)
Richard Trigaux, alas, is too optimistic about the Genesis scientists being able to retrieve "most" of their planned data.  The latest news is that they will indeed be able to properly measure the amount of noble gases in the Sun, since those (except for argon-40, which is irrelevant) exist only in microscopic amounts in Earth's atmosphere and water, and so weren't affected by the crash's contamination.  But that was only their third scientific priority -- the top ones were to measure the isotopic ratios of the Sun's oxygen and nitrogen (especially the former), and unfortunately those have been very badly contaminated indeed.  It's questionable whether they'll be able to retrieve any meaningful results on those.
*


The team first came with an optimistic statement, pity of it did not worked. There was many expectations about this experiment.




QUOTE (BruceMoomaw @ Dec 25 2005, 11:23 PM)
As for Solar Probe -- whose design has been modestly changed lately, without harming its total science output -- see the very informative official Web page at  http://solarprobe.gsfc.nasa.gov/ .  Solar scientists would absolutely love to fly this mission, but it will cost as much as a New Frontiers mission and so NASA has yet even to officially propose it.  (It's even been suggested that it should be included in the New Frontiers program.  But that, in turn raises the question of whether ALL competitive-proposal programs for space science -- Solar System, Mars, astronomy, magnetospheric science or what have you -- that are in the same cost range should be folded up together into a single competitive space-science proposal program, which might well make sense.)

There is no doubt at all, however, that we can make Solar Probe work -- amazingly, we already have almost all the technology we need for it.  Extensive ground tests of that dunce-cap shaped carbon heat shield show that not only does it provide full protection against the heat, but it vaporizes considerably less than expected and so won't contaminate the probe's plasma measurements.  The only thing that requires any additional work at this point is the design for the "plasma periscope" that would peep around the edge of the heat shield and divert a small amount of the outflowing solar plasma to the analyzers behind the shield.
*


So there is REALLY such a project?

Woww.

Thank you for the link, Bruce, it is very interesting. I hope such a mission will fly one day.

Of course at only 4 sun radii of the surface of the sun, it will be unmanned. Not yet any Bush plan for Sun colonization?

And for the great dive INTO the Sun, we shall see a bit later.
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edstrick
post Dec 26 2005, 11:12 AM
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Unfortunately, the Solar Probe mission, or whatever it's name of the year is... has seemed to always be 10 years in the future. Rather like "Main Belt Multi Asteroid Rendezvous", which has been repeat-studied and repeat-proposed since the early 70's. If <whimper> Dawn flies, we'll finally get that one.
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ljk4-1
post Dec 26 2005, 06:03 PM
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QUOTE (Richard Trigaux @ Dec 26 2005, 04:27 AM)
The team first came with an optimistic statement, pity of it did not worked. There was many expectations about this experiment.
So there is REALLY such a project?

Woww.

Thank you for the link, Bruce, it is very interesting. I hope such a mission will fly one day.

Of course at only 4 sun radii of the surface of the sun, it will be unmanned. Not yet any Bush plan for Sun colonization?

And for the great dive INTO the Sun, we shall see a bit later.
*


Maybe if we tell Bush there's a lot of oil on the Sun....


--------------------
"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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