Modernday Journey to the Center of the Earth

[zakur]

Earth Probe Plan Would Blast a Path to the Core (http://news.nationalgeographic.com/news/2003/05/0514_030514_earthcore.html)

scientist proposes sending a grapefruit-size communication device into the heart of the Earth by blasting a crack in the surface and pouring in a huge quantity of molten iron. The weight of the liquid metal would crack the Earth for more than 1,800 miles (3,000 kilometers), carrying the probe to the planet's core in about a week.

The probe would measure temperature, electrical conductivity, and chemical composition, and would beam back data as encoded sound waves to a surface detector.

David J. Stevenson of the California Institute of Technology in Pasadena outlines the plan in the May 16 issue of the scientific journal Nature.

...

According to Stevenson, the crack that will have to be blasted into the Earth's surface to launch the probe will need to be several hundred meters in depth, and about a foot (30 centimeters) wide, to accommodate a volume of about 100,000 to several million tons of molten iron.

The instant the crack opens, the entire volume of iron will be dropped in, completely filling the open space, he said. Through the sheer force of its weight, the iron will create a continuing crack that will open all the way to the planet's core 3,000 kilometers (1,800 miles) below. Anything on a smaller scale may not work; anything larger will be even more expensive, so Stevenson thinks a crack of those dimensions is about right.

"Once you set that condition up, the crack is self-perpetuating," Stevenson said. "It's fundamentally different from drilling, where it gets harder and harder—and eventually futile—the farther you go down."

The iron will continue to fall due to gravity because it is about twice the density of the surrounding material. Riding along in the mass of liquid iron will be one or more probes made of a material robust enough to withstand the heat and pressure. The probe will perhaps be the size of a grapefruit but definitely small enough to ride easily inside the 12-inch (30-centimeter) crack without getting wedged, Stevenson said.Several million tons of molten iron?! :eek:

[Crossbow]

I heard about this experiment as well and I have some serious doubts as to if it can be done or not.

After all, modern foundaries can handle about 20 tons of molten steel, and he is talking about millions of tons. That means the foundary would have to be located on site and have a capacity that that is thousands of times greater than any current foundary.

At bbest, it sounds very, very difficult!

[EdipisReks]

maybe we'll get lucky and an iron asteroid will impact the earth right where the experiment is supposed to take place ;)

[to.by]

As far as I know, the mantle is liquid. How does he propose to make a crack in a liquid?

[Agammamon]

Iron is denser than the liquid rock in the mantle. Once it had penetrated the crust it would just sink through the mantle, probably retaining most of its shape on the way down.

[Colloden]

Originally posted by zakur
scientist proposes sending a grapefruit-size communication device into the heart of the Earth by blasting a crack in the surface and pouring in a huge quantity of molten iron. The weight of the liquid metal would crack the Earth for more than 1,800 miles (3,000 kilometers), carrying the probe to the planet's core in about a week.

The probe would measure temperature, electrical conductivity, and chemical composition, and would beam back data as encoded sound waves to a surface detector.


I can see the data it would send back now....

Temperature : That of molten iron
Electrical conductivity : That of Iron
Chemical composition : Iron (molten maybe ?)

[Dancing David]

There was some movie in the sixties/seventies where they drill a hole and drop a nuclear bomb in it and then itsplits the earth in half, can't wait to see what movies this spawns.


Funk On

[davefoc]

Why do you need the crack to start it. Build a tower and construct your probe above ground. When your tower gets high enough there will be enough downward force on the nose of the probe to drive it into the earth.

This way you can start with a super hard and shaped nose and just attach sections of iron above the nose. You might attach the sections by screwing one to the next. Their might be other advantages also. The sides of the sections are obviously going to be smoother than the sides of the probe if it is made by poring molten metal into a hole in the ground.

I don't know how to do even a rough calculation on the feasibility of a probe that would fall toward the center of the earth but my gut feel is that it might work. I am not so sure of about the transmitter and the power source for the transmitter. Once the probe made it threw the earth's solide surface into liquid layers it seems like all chance of acoustic communication would be lost.

Maybe if one could figure out how to get a neutrino generator in a sufficiently small package you could modulate the output to communicate. There have been some attempts to try to beam neutrinos from nuclear reactors to remote neutrino detectors. So the idea may not be completely loony tunes, but it probably is.

Of course there is the small issue of protecting your transmitter against the enormous heat. Don't know how to do that either. Maybe carry a large supply of a substance that is pumped outside the transmitter and boils away fast enough to keep its temperature low enough so that it can function.

And then to the power source. Hmm. maybe the boiling away of your cooling substance could drive a generator somehow.

I thought the question was interesting enough to think about but I wonder whether the guy has managed to do even preliminary feasibility calculations.

[Captain Trips]

Seems to me that, with the temperatures and pressures involved, the material needed to construct the probe has already been named "Unobtanium." Or perhaps "Adamantium" would work. :p

[Mercutio]

Heard this guy on 2 different NPR shows. Seems he feels the only way to create the crack initially will be with a nuclear device. So let's add that to the problem of getting the molten iron to the location. Or maybe that makes it easier--just drop the probe right there, where the planet is glowing...

[shanek]

Apparently, this is just an hypothesis.

http://www.news24.com/News24/Technology/News/0,,2-13-1443_1360385,00.html

The science fiction plan is laid out in the article "Mission to Earth's core - a modest proposal" in which Stevenson calculates that it would take a blast equivalent to several megatonnes of TNT, a small nuclear device or an earthquake of magnitude 7 on the Richter scale to pierce the earth's crust.

Stevenson also calculates that the experiment would need to commandeer all of the world's iron foundries for anything from an hour to a week and admits that there is no guarantee of success.

"Frankly, I would be surprised if this really works," he wrote.

[Agammamon]

Originally posted by davefoc
Why do you need the crack to start it. Build a tower and construct your probe above ground. When your tower gets high enough there will be enough downward force on the nose of the probe to drive it into the earth.



Or how about you make your superhard penetrator and put the probe in it and a shock absorber on the back. The all you have to do is detonate nukes above it to drive it into the ground. Sort of like the Orion concept except in the opposite direction.

[davefoc]

Agammamon,
Thanks for reviving the thread a bit. There may be some merit to the idea of forcing the probe down with explosives. Like everything else about this idea I don't have any idea how to even begin to evaluate if it is possible.

I think the basic idea is interesting but I don't know any way of doing a rough feasibility calculation on it. The questions to me are:
1.how much pressure is required to drive the probe through solid rock?
2. can you make the probe head hard and strong enough to prevent destruction
3. can the probe be dense enough to overcome the friction from the rock that closes in around it


I thought about just using convential drilling technology to get a deep hole to start with and then just removing the pipe and filling the hole with the probe.

The original idea was a big iron rod, but what would happen if instead of an iron rod you used depleted uranium, a much denser material?

One use for the idea, might be to bury nunclear waste once the probe began to fall on its own, maybe you could fill some sections with nuclear waste.

Admittedly this all seems fanciful, but I'm not quite sure what the problems with the idea are. It would be interesting to get comments from somebody who might be able to address some of the basic feasibility issues.

[Agammamon]

It might even be in the realm of possibility to channel some of the blast around the penetrator to cut the rock ahead of it.