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Lord Jubjub
2010-Mar-02, 02:33 AM
. . .could you send a probe?

Jacket it in a liquid hydrogen/helium jacket on the scale close to zero K. How close could you put a single pass probe and return usable data?

Hornblower
2010-Mar-02, 02:38 AM
. . .could you send a probe?

Jacket it in a liquid hydrogen/helium jacket on the scale close to zero K. How close could you put a single pass probe and return usable data?

A lot would depend on how fast the probe is going and how robust the protection is. Sun-grazing comets have passed within 200,000 miles of the photosphere without being totally vaporized, if I am not mistaken.

korjik
2010-Mar-02, 07:35 AM
Also depends on what you want for info. Most probes need to be able to see the sun, so they wouldnt survive long close to the sun.

Murphy
2010-Mar-02, 05:00 PM
Well there's Solar Probe+ (http://en.wikipedia.org/wiki/Solar_Probe%2B), which is due to orbit the Sun at just 6 million kms. I think that is the closest any probe has been sent to the Sun (unless there were some other Sun-glancing craft that briefly went closer?). Solar Probe+ uses some interesting heat mitigation techniques, I suppose with more advanced methods you could sent probes much closer, I don't know what the limit would be for machines made of normal materials though.

joema
2010-Mar-02, 05:13 PM
. . .could you send a probe?

Jacket it in a liquid hydrogen/helium jacket on the scale close to zero K. How close could you put a single pass probe and return usable data?

This was discussed extensively in this thread:

http://www.bautforum.com/space-astronomy-questions-answers/97762-nuking-sun.html

Summary: an instrumented probe which survives until reaching the solar surface has been discussed, and may be possible: http://www.theaustralian.com.au/news/nation/crashing-plan-for-space-era-take-off/story-e6frg6nf-1111114564870

The solar surface (photosphere) is about 5,300C, and a sun spot only about 3,500C. Energy flux is roughly 62 megawatts per square meter. The heat shields of the Galileo atmospheric entry probe may have sustained temperatures and heat fluxes above that point, yet survived long enough to send back data: http://en.wikipedia.org/wiki/Galileo_probe

JohnD
2010-Mar-03, 09:31 AM
I don't think that any amount of cold liquid gases would get you far, unless you were a comet, and they're BIG.
But what about a sun shade? Highly reflective material, with a radiator on the back, held between sun and probe, either directly or by linked navigation.

I imagine it would work, given suitable material, until the radiator was glowing so hot that the probe was affected. To get nearer to the Sun than that, a bigger sunshade is needed so that the probe could stand off further behind the shade.

John