On: A Nuclear Probe to Explore Earth’s Interior

[gipp]

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.

[dredmorbius → gipp]

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

[ars → gipp]

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.

[kijin → ars]

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