The post states that tungsten "...has a low corrosion rate at elevated temperatures." This is not accurate.<p>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, <a href="http://labfus.ciemat.es/AR/2011/C_004/AM_4x.pdf" rel="nofollow">http://labfus.ciemat.es/AR/2011/C_004/AM_4x.pdf</a>)<p>Tungsten is great for high temperature use in vacuum, neutral (the inert gases) or reducing environments (hydrogen, for example). You can use it nearly up to its melting point in those conditions if you aren't too dependent on structural integrity.<p>In oxidizing environments (air, oxygen, water, halogens, silicates, etc.) it fails quite rapidly. Molten rock is replete with chemical species that react with tungsten at elevated temperatures.<p>At 2000°C, the tungsten blanket covering the Co60 heat source would be corroded away, I'll guess, within a week of launch on its journey to the center of the earth.<p>Although it would be incredibly costly, they might have better luck with iridium or rhenium.<p>Nevertheless, a fun mission to think about.
A Caltech professor, David Stevenson, proposed a temperature-resistant probe immersed in a blob of molten iron: Stevenson, David J. Mission to Earth's Core - A Modest Proposal. Nature, 423, 239-240, 2003a. No radioactivity necessary, and the PDF is here: <a href="http://mathcs.albion.edu/~mbollman/Honors/ToTheCore!.pdf" rel="nofollow">http://mathcs.albion.edu/~mbollman/Honors/ToTheCore!.pdf</a>
A patent for a similar device from back in the 60s:
<a href="http://www.google.com/patents/US3115194" rel="nofollow">http://www.google.com/patents/US3115194</a><p>Happened to see it while archiving the inventor's papers. :)
What a fascinating proposition. FYI: This blog article is from 2013 and is about scientific papers written in 2008 and 2005. A few minutes of cursory Googling turns up nothing else.
Did this go anywhere? The only papers if find that reference the original ideas (2005 and 2008) mention nuclear waste that melts itself into the Earths core.
The article also suggests using the probe to analyze the composition of other planets. Is that doable? It seems pretty tough to me to carry on a space ship a nuclear probe hot enough to melt rocks.
With the accelerating change in the earth's magnetic field it would be fantastic to drop a few of these bad boys and see what's actually going on down there.
This sounds like a more practical version of David J. Stevenson's 2003 earth probe proposal: <a href="http://news.nationalgeographic.com/news/2003/05/0514_030514_earthcore.html" rel="nofollow">http://news.nationalgeographic.com/news/2003/05/0514_030514_...</a>
This sounds like a controlled version of the China syndrome. <a href="http://en.wikipedia.org/wiki/Nuclear_meltdown#China_Syndrome" rel="nofollow">http://en.wikipedia.org/wiki/Nuclear_meltdown#China_Syndrome</a>
> <i>As the probe descents deeper, the rate of descent will gradually slow until the probe reaches a depth of 100 km after ~30 years</i><p>The article doesn't mention - why will the probe stop descending?
What was that recent speculation based on seismic resonance about there possibly being a large amount of previously un-theorized water, rather than rock, somewhere in the interior?
"transform some of the energy from radioactive decay"<p>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.