Probe that can land on the sun?
Ke...@computer.com
I am curious if there are any materials that maintain their solid form at
6,000 degrees. That is the temp of the surface of the sun. If there was
something you could construct the shell out of, that did not melt, the you
could conceivabley put a probe onto the surface of the sun.
Inside it could have a nuclear powered energy source and some way to
cooling internally. Perhaps.
I know it sounds crazy, I am just curious. How to get through the
1,000,000 degree corona is a problem. How to survive the crushing gravity
is another one. But of all these factors, the 6,000 degree part seems the
most approachable.
Kevin
MONTMACH
>
>I am curious if there are any materials that maintain their solid form at
>6,000 degrees. That is the temp of the surface of the sun. If there was
>something you could construct the shell out of, that did not melt, the you
>could conceivabley put a probe onto the surface of the sun.
>
>
Hello Kevin,
The material you need is called unatanium, avalible from the McMaster-Carr
company. There ad says everything under the sun. Sorry I could not resist.
Dave
~~~~~~~~~~~~~~~~~~~~~
Dave Griffith
The R.A.T.T.-works
Monterey Machine Products
1504-A Industrial Park Street
Covina, CA 91722 U.S.A.
http://www.rattworks.night.net/
C D Edmondson
Ke...@Computer.com wrote:
>I am curious if there are any materials that maintain their solid form at
>6,000 degrees. That is the temp of the surface of the sun. If there was
>something you could construct the shell out of, that did not melt, the you
>could conceivabley put a probe onto the surface of the sun.
>Inside it could have a nuclear powered energy source and some way to
>cooling internally. Perhaps.
>I know it sounds crazy, I am just curious. How to get through the
>1,000,000 degree corona is a problem. How to survive the crushing gravity
>is another one. But of all these factors, the 6,000 degree part seems the
>most approachable.
>Kevin
I read a loooong while ago NASA was considering sending a probe to the
sun with layers of material that would boil off like onion layers to
protect the instruments inside till its final destruction.
Christopher
==============
Working on it!
Jens A. Lerch
lpu...@netcom.com (Lance Purple) wrote:
>Kevin <Ke...@Computer.com> wrote:
>> I am curious if there are any materials that maintain their solid
>> form at 6,000 degrees. That is the temp of the surface of the sun.
>Tantalum Carbide melts at 3800 celsius, and that's about as high
>as it goes. You aren't going to find anything that stays solid
>at 6000 celsium; you'll have to settle for a probe that melts.
>Anyway, your probe's lifetime won't be ruled by temperature, but by
>how long you can sustain a communications link with it. It'll fall
>right through the photosphere in less than one minute, and after 15
>minutes or so, it'll be so deep into the convective zone that there
>isn't much chance of talking to it any more.
>Now, tungsten is pretty difficult to melt, so let's calculate how
>long a tungsten sphere could survive inside the Sun. We'll give
>it a head-start by cooling it down to a few degrees Kelvin first.
>It turns out that you get about 0.5 sec of life for every 1 cm. of
>radius, so a 20 m. tungsten sphere could survive our little ride
>into the Sun's convective zone without melting; and you can double
>the time-to-melt by doubling the radius.
You have to consider that a 20m tungsten sphere has a mass of 80,000
metric tons. That's twice the annual current worldwide production of
tungsten and more mass than the sum of all satellites ever launched.
I don't think the results of this probe would be worth the effort.
At least not now, maybe if there are lot of mines and colonies in
space, which will have a great interest to know how the sun works.
Jens A. Lerch
fxw...@rz.uni-frankfurt.de
Please take a look at my Space Statistics Page at
http://www.rz.uni-frankfurt.de/~fxws326/space.htm
Cathy James
>> I am curious if there are any materials that maintain their solid
>> form at 6,000 degrees. That is the temp of the surface of the sun.
>Tantalum Carbide melts at 3800 celsius, and that's about as high
>as it goes. You aren't going to find anything that stays solid
>at 6000 celsium; you'll have to settle for a probe that melts.
Hmm, this assumes no active refrigeration. David
Brin had some interesting speculations on this in his novel
_Sundiver_. I'm not sure how realistic his proposals are;
essentially, he's saying that you use the spacecraft's power
to refrigerate part of the vehicle and overheat the rest, then
cool the overheated section by using it to heat-pump a laser.
>Anyway, your probe's lifetime won't be ruled by temperature, but by
>how long you can sustain a communications link with it. It'll fall
>right through the photosphere in less than one minute, and after 15
>minutes or so, it'll be so deep into the convective zone that there
>isn't much chance of talking to it any more.
You seem to be assuming that the probe starts at rest
with respect to the Sun. It's more likely to be following a
high-eccentricity elliptical orbit, with a carefully chosen
perigee.
-----------------------------------------------------------
| Cathy James <caj...@alumni.princeton.edu> PPSEL, N5WVR |
| |
| |
Paul Dietz
Lance Purple wrote:
> Anyway, your probe's lifetime won't be ruled by temperature, but by
> how long you can sustain a communications link with it. It'll fall
> right through the photosphere in less than one minute, and after 15
> minutes or so, it'll be so deep into the convective zone that there
> isn't much chance of talking to it any more.
A big problem here is getting the probe to the sun's
surface at low velocity. Drop it from infinity, and
it will be travelling at 617 km/s when it reaches
ths photosphere, which you would cross in a quarter
of a second. At a surface density of 2e-8 g/cc,
the aerodynamic heating will be around 2 trillion
watts per m^2, far exceeding the heating from the
sun's luminosity.
Paul
Bill Bonde
Lance Purple wrote:
>
> Kevin <Ke...@Computer.com> wrote:
>
> > I am curious if there are any materials that maintain their solid
> > form at 6,000 degrees. That is the temp of the surface of the sun.
>
> Tantalum Carbide melts at 3800 celsius, and that's about as high
> as it goes. You aren't going to find anything that stays solid
> at 6000 celsium; you'll have to settle for a probe that melts.
>
> how long you can sustain a communications link with it. It'll fall
> right through the photosphere in less than one minute, and after 15
> minutes or so, it'll be so deep into the convective zone that there
> isn't much chance of talking to it any more.
>
with all the data stored in it which would then radio back to the main
ship once it got out far enough to communicate again. Designing this
seems tough though. Perhaps instead one could just have the sphere skip
through the edge of the Sun and then radio back information once it
escaped.
David Cogen
> It turns out that you get about 0.5 sec of life for every 1 cm. of
> radius, so a 20 m. tungsten sphere could survive our little ride
> into the Sun's convective zone without melting; and you can double
> the time-to-melt by doubling the radius.
>
>
> density = 19.3 g/cm^3
> specific heat (2000K) = 0.04 cal/g deg.C
Not being a physicist I cannot do the math. But I seem to remember that water
has an extremely high capacity; Am I correct? How about making the sphere from
ice instead? Much much much cheaper than tungsten.
I expect that most of the protection will come not from the heat capacity of
the ice or water, but from the latent heat of melting. Can someone do the math
and come up with an equivalent protection-to-thickness-ration for an ice
sphere?
Ian Stirling
Cathy James <Cathy.Jam...@nt.com> wrote:
:>> I am curious if there are any materials that maintain their solid
:>> form at 6,000 degrees. That is the temp of the surface of the sun.
:>Tantalum Carbide melts at 3800 celsius, and that's about as high
:>as it goes. You aren't going to find anything that stays solid
:>at 6000 celsium; you'll have to settle for a probe that melts.
: Hmm, this assumes no active refrigeration. David
: Brin had some interesting speculations on this in his novel
: _Sundiver_. I'm not sure how realistic his proposals are;
: essentially, he's saying that you use the spacecraft's power
: to refrigerate part of the vehicle and overheat the rest, then
: cool the overheated section by using it to heat-pump a laser.
The problem is of course, that it's too hot, it may work on venus...
Anyway, let's assume it's possible.
Right, so what's in this?
Essentialy, you have:
99% efficiant laser (Ok so far, IIRC 50% has been hit already)
Power source of some kind
Heat-pump
thermo-electric converter
Let's think about this.
The probe is not heating up, as otherwise it's pointless.
Nothing inside is 100% efficiant.
So, we make everything .5% more efficiant, and the probe interior slowly
cools, now we connect a thermo-electric converter between the outside
and the inside, and we can draw power from it, to restore the balance.
Now, connect this power to a heater outside.
Oops, haven't we just made a perpetual motion device?
The star won't cool down, if we have enough of these in it.
(I suspect a logic error here, tired)
:>how long you can sustain a communications link with it. It'll fall
:>right through the photosphere in less than one minute, and after 15
:>minutes or so, it'll be so deep into the convective zone that there
:>isn't much chance of talking to it any more.
<snip>
What limits heat transfer through a superconductor?
Is it possible to tow a cable?
(Yes, you would need a BIG heatsink)
--
Ian Stirling. Designing a linux PDA, see http://www.mauve.demon.co.uk/
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Money is a powerful aphrodisiac, but flowers work almost as well.
Robert A Heinlein.
Frank Crary
In article <6guhb6$n...@dfw-ixnews9.ix.netcom.com>, kbm <> wrote:
>NASA/JPL has an initiative called Ice and Fire
>(http://www.jpl.nasa.gov/ice_fire/) that you might want to look at. The
>solar probe is going to be tough to design. The europa orbiter is also hard
>because of the radiation environment
Actually, the radiation environment is one of the less challenging
problems facing the Europa Orbiter. Fuel requirements are a much
greater problem. Assuming chemical propulsion, it is very difficult
to get the delta v for orbital insertion below 6 km/s. For storable
fuels, that translates to a Galileo-sized launch to put a small-end
Discovery-sized spacecraft in orbit around Europa. Since the JPL
web page also mentions radar sounding, the spacecraft power requirements
will be quite high, and jovian orbits are a difficult place for a
spacecraft that requires high power (especially when it's a small
spacecraft...)
Frank Crary
CU Boulder
Cathy James
>So, we make everything .5% more efficiant, and the probe interior slowly
>cools, now we connect a thermo-electric converter between the outside
>and the inside, and we can draw power from it, to restore the balance.
>Now, connect this power to a heater outside.
>Oops, haven't we just made a perpetual motion device?
No, the amount of power you'll get from your thermo-electric
converter will always be less than the power required to cool down
the vehicle. You'll need an independent power source.
For analogy, I could put refrigerators and batteries
in my house on a 100 F day, and cool the entire house, batteries,
power system, etc. down below 100 F, dumping the waste heat outdoors.
No thermodynamic law is violated.
This technique won't let you fly around in the photosphere
because no materials can handle the waste heat side, but (as used
in the book) it lets the vehicle survive longer and closer to the
surface than one consisting only of passively ablated shielding.
Ian Stirling
Bill Bonde <std...@mailexcite.com> wrote:
: Lance Purple wrote:
:>
:>
:> > I am curious if there are any materials that maintain their solid
:> > form at 6,000 degrees. That is the temp of the surface of the sun.
:>
:> Tantalum Carbide melts at 3800 celsius, and that's about as high
:> as it goes. You aren't going to find anything that stays solid
:> at 6000 celsium; you'll have to settle for a probe that melts.
:>
:> how long you can sustain a communications link with it. It'll fall
: You could fire a projectile back out of the Sun from the melting sphere
: with all the data stored in it which would then radio back to the main
Hmm, if you could get gamma ray lasers to work, you could probably get
10 or so bits per blast...
--
Ian Stirling. Designing a linux PDA, see http://www.mauve.demon.co.uk/
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Things a surgeon should never say.
Better save that for the autopsy.
J. Kieffer-Olsen, M.Sc.(Eng.)
In article <353D0E00...@mailexcite.com>
std...@mailexcite.com "Bill Bonde" writes:
> You could fire a projectile back out of the Sun from the melting sphere
> with all the data stored in it which would then radio back to the main
> ship once it got out far enough to communicate again. Designing this
> seems tough though. Perhaps instead one could just have the sphere skip
> through the edge of the Sun and then radio back information once it
> escaped.
Thought of this just before reading your article :-)
The only variation in my version is that the projectile needs no
communication capability. It's simply retrieved as is!
--
Jens Kieffer-Olsen