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A Nuclear Probe to Explore Earth’s Interior

beyondearthlyskies.blogspot.com

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Re: A Nuclear Probe to Explore Earth’s Interior

#51

Post by jimmyswimmy »

youaredoomed wrote: post #50

Why not place the sphere into a pre-made hole so it will make it to the center of the planet faster?

A couple reasons, I'd bet - first, a hole wide enough to fit the probe is pretty unusual, and would be an expensive research project all on its own. Second, the probe near the surface will emit the largest signal, so you get some really good SNR data to calibrate your algorithms against. If you don't understand the signals you're receiving when it's shallow, you won't understand them any better when it's deep - a regime where we have more theories than data. Or maybe something else.

Re: A Nuclear Probe to Explore Earth’s Interior

#53

Post by kijin »

ars wrote: post #36
gipp wrote: post #24

Earlier quoted context omitted.

Erm. If it's melting the rock around it, then the rock is your cold sink. By the time the temperature of the rock catches up with the probe, it's already molten anyway.

The rock would not work as a cold sink - the cold rock is too far from the probe. The rock right near the probe is at almost the exact same temperature.

And that's exactly why the probe will take 30 years to move 100km. It's going to be a very slow process.

Re: A Nuclear Probe to Explore Earth’s Interior

#54

Post by dredmorbius »

gipp wrote: post #24
ars wrote: post #22

"transform some of the energy from radioactive decay" Not so simple. You need a hot source and a cold sink to transform energy. Where's your cold sink? This thing is intended to melt what's around it, and the outside of the probe is not that different in temperature from the inside.

Erm. If it's melting the rock around it, then the rock is your cold sink. By the time the temperature of the rock catches up with the probe, it's already molten anyway.

More specifically: the interior of the probe is 2000F, the surrounding rock melts at 1000F. That's a pretty good temperature gradient right there.

Re: A Nuclear Probe to Explore Earth’s Interior

#56

Post by dredmorbius »

spingsprong wrote: post #49

Would this produce a new volcano? Or would the magma just freeze as it travels through the relatively cool hole?

My read is that the rock would re-fuse above the probe, so no:

"Heat generated from the decay of radioactive cobalt-60 allows the probe to melt its way into the Earth. The probe is estimated to melt down to a depth of 20 km in ~1 year. As the probe descents deeper, the rate of descent will gradually slow until the probe reaches a depth of 100 km after ~30 years. By melting its way into the Earth, the probe will leave behind a wake of molten material. Subsequent re-crystallisation of the molten material will generate intense acoustic signals."

Re: A Nuclear Probe to Explore Earth’s Interior

#57

Post by 4ad »

TallGuyShort wrote: post #40
toomuchtodo wrote: post #18

Earlier quoted context omitted.

Increase in density as you get closer to the core.

On top of which gravity is going to lessen as you get to the center of mass, so even a little resistance will eventually become extremely significant...

At 100km, the gravitational acceleration is actually higher than at the surface.

http://www.wolframalpha.com/input/?i=gravitational+accelerat...

In fact, it increases until 3500km below the surface (2800km radius).

http://en.wikipedia.org/wiki/Gravity_of_Earth#mediaviewer/Fi...

Re: A Nuclear Probe to Explore Earth’s Interior

#58

Post by gambiting »

Natsu wrote: post #44
ridgeguy wrote: post #41

The post states that tungsten "...has a low corrosion rate at elevated temperatures." This is not accurate. Tungsten oxidizes in air beginning around 600°C and as the temperature increases, the tungsten oxide layer scales off, exposing underlying metal to further oxidation. (see, for example, http://labfus.ciemat.es/AR/2011/C_004/AM_4x.pdf ) Tungsten is great for high temperature use in vacuum, neutral (the inert gas…

> A self-sinking probe is basically a dumb probe measuring less than 100 cm in diameter - a lump of nuclear waste encapsulated in a tungsten sphere and sunk into the ground. Even more so if you wonder if it couldn't be a way to dispose of waste. Also, if corrosion was an issue, perhaps they could coat it with something?

Nuclear waste is waste because it doesn't produce enough heat anymore to be useful in production of electricity. So I doubt that spent nuclear fuel would be able to produce 1000C+ temperatures for 30 years to bury itself deep enough.

Re: A Nuclear Probe to Explore Earth’s Interior

#59

Post by DCKing »

gambiting wrote: post #58
Natsu wrote: post #44

Earlier quoted context omitted.

> A self-sinking probe is basically a dumb probe measuring less than 100 cm in diameter - a lump of nuclear waste encapsulated in a tungsten sphere and sunk into the ground. Even more so if you wonder if it couldn't be a way to dispose of waste. Also, if corrosion was an issue, perhaps they could coat it with something?

Nuclear waste is waste because it doesn't produce enough heat anymore to be useful in production of electricity. So I doubt that spent nuclear fuel would be able to produce 1000C+ temperatures for 30 years to bury itself deep enough.

IANAG, but it probably doesn't need to get 100km under the ground. It only needs to go to the depth at which the nuclear waste stops being a problem.

With a good amount kilometers of rock between the surface and the waste, the danger is already gone. Furthermore, melting the waste and have it move thorugh the mantle will lower its concentration and will over time have the heavy materials fall into the core.

My guess is that the point at which the nuclear waste becomes less problematic than current methods will probably occur quite quickly, just a few kilometers if that. The point at which the tungsten corodes and the waste can be swept away doesn't seem to be that deep either.

Re: A Nuclear Probe to Explore Earth’s Interior

#60

Post by kefka »

msds wrote: post #47
ISL wrote: post #15

Earlier quoted context omitted.

Tungsten is usually sintered with a binder. I'm unaware of any welding techniques that work with it. For a similar fabrication job, check out the LARES satellite (which is awesome, elegant, and the densest free-falling object in the Solar System): http://www.esa.int/Our_Activities/Launchers/Launch_vehicles/...

Laser, electron-beam and atomic-hydrogen (no, not crackpot-conspiracy-theory "HHO" atomic hydrogen) welding can work with tungsten, in theory...

Interesting that you mention HHO as crackpot theory.

What I am familiar with are kits to generate HHO gas for hydrogen welding. Mainly, they rely on electrolysis of water and gathering of H2. Of course, the amateur kits have blowback preventers and other tech to prevent gas explosions.

But nothing crackpot. Guess I don't read the cranks documents.

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