Falling to Earth's Core in a Big Blob of Iron

Colin Douglas Howell writes "Um...wow. I found this idea via the BBC, (see also the Nature article), but it's really worth reading the annotated paper on the subject. (Gotta love the title.) Basically, you drill a hole in the crust, blast a big crack in it, inject a huge mass of molten iron with a little probe floating inside (made out of material which won't melt or dissolve in the iron), and let the iron mass sink to the core by gravity, carrying the probe with it. (The initial crack grows downward as the iron sinks.) As the probe falls, it sends data back using seismic signals that can be picked up with a gravitational wave observatory like LIGO, but coupled to the ground. Of course, there are enormous problems with the whole thing, but it's still cool to read about. To me, the idea is even neater because it was dreamed up by Dave Stevenson, one of my old professors (and one of the best professors I've ever had). I hope he doesn't mind being Slashdotted. :-)"

And that's how the Earth broke in two

And everyone on the planet was killed. So, children, remember, don't try to drill to the center of your planet without the proper tools.

Alien 4th Grade Class on "History of Stupid Mistakes"

Crack in the World, 1965, Dana Andrews

Crack in the World (1965) [imdb.com]

Plot Summary for
Crack in the World (1965)

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Dr. Steven Sorenson (Andrews) plans to tap the geothermal energy of the Earth's interior by means of a thermonuclear device detonated deep within the Earth. Despite dire warnings by fellow scientist Ted Rampian (Moore), Dr Sorenson proceeds with the experiment after secretly learning that he is terminally ill. This experiment causes a crack to form and grow within the earth's crust, which threatens to split the earth in two if it is not stopped in time.

Immortal Dialogue [bluemountains.net.au]

Layperson: What if the crack keeps going - right around the world? What happens then?
Scientist: Where the land masses split the oceans will be sucked in, and the colossal pressure generated by the steam will rip the earth apart - and destroy it.
Layperson: You mean - the world will come to an end!?
Scientist: The world as we know it, yes. As a cloud of astral dust, it will continue to move within the solar system.
[That's what's known as "scientific consolation"....]

Re:Crack in the World, 1965, Dana Andrews

I seem to recall this being done in cracks in metal and even plastic (?) surfaces on light aircraft. The quickest, best explanation googled for (stress holes reduce) is here. [reliability.com]

Their explanation goes to crystalline structures, and stress and loadbearing being a function of surface area. Basically the crack hitting the hole allocates the stress around a much larger unit of area. So the force per area is much smaller than when there is no hole and only a crack. The reduced force per area can then be managed by the material and won't crack further.

Note, the hole must be smoothly finished (you did use the smooth finishing h-bomb and not the rough cut h-bomb) and than there are no more dislocations to start a new crack.

That's my laymen's understanding.

Pretty neat though, the final scene with two moons. THIS MOVIE SCARED THE HELL OUT OF ME!

Retro-revenge.

"To me, the idea is even neater because it was dreamed up by Dave Stevenson, one of my old professors (and one of the best professors I've ever had). I hope he doesn't mind being Slashdotted. :-)""

That's easy for you to say. You already have your degree.

The end..

And then when the probe stops the earths core from spinning we will send down a team to ignite nuclear bombs to restart it.

There's the problem....

made out of material which won't melt or dissolve in the iron

Well...thats easy then

Re:There's the problem....

That'd work, but only if there was some place for the heat to go. Can't get rid of heat, right, all you can do is move it around? Hard to do that when you're surrounded by friggin molten iron.

That's not quite true. Consider a refrigerator. It consists of an insulator layer and a heat pump. When heat leaks past the insulator it gets sucked back out and dumped.

So you could do the same thing in the earths core, use brick as the insulating layer, and run a refrigerator to pump the heat out, and increase the temperature of the molten iron just outside the insulator. Molten iron is a good conductor of heat, so convection would carry the heat away from the probe.

I must admit I'm more worried by the unbelievable pressure of hundreds of miles of rock, oh yeah, that and the nuclear device they'd need to start off the crack...

Re:There's the problem....

And you don't want to get rid of the heat too quickly either. It has to be hot enough to keep melting the rock as it goes down.

Oh I wouldn't worry about that. After the first few miles, the temperature of the surrounding rock would be enough to keep the iron molten. Ever see pictures of lava moving through water? Kinda like that, only instead of being chilled on the outside and kept warm from the inside, it's the other way around.

Besides, if your probe's cooling system is good enough to actually chill several million tons of iron whilest encased in liquid silicate rocks, you could really dispense with the whole molten iron thing and just make the thing dense and massive enough to fall of its own accord and provide it with a heat source to keep the outside piping hot while your magical freon unit maintains room temperature on the inside.

For the coming "hole to China" questions/jokes

People might actually crack a joke concerning the possibility of boring a hole to China using this technique. I would like to take the time to point out that this isn't possible using this technique.

If you ignore friction, the rotation of the earth, and other "complications", then it would be possible to use this technique to bore a hole right through to China. Imagine the sudden appearence of a tunnel that goes straight through the Earth. If the mass distribution in the earth was uniform (which it is not), a person could jump into this tunnel and then come back up on the surface on the Earth on the other side (China), much like the motion of a pendulum swinging up and down again. Assuming that the journey began with zero initial speed (simply dropping into the hole), your speed would increase and reach a maximum at the center of the earth, and then decrease until you reached the surface on the other end, at which point the speed would again be zero. The gravitational force exerted on the traveler would be proportional to his distance from the center of the earth: it's at a maximum at the surface and zero at the center. If there were no friction, there would be no energy loss, so you could oscillate into and out of the tunnel forever.

Given the physics behind this theorized stunt, boring a hole clear through to China would be impossible. It would require some extra application of force to tunnel "upwards" after reaching the Earth's core.

So no, unlike a Bugs Bunny cartoon, we cannot use molten iron to dig a hole to China. Not like this, anyways.

Re:For the coming "hole to China" questions/jokes

Best case scenario (i.e., no air, no uncomfortable smacking into the surrounding rock at speeds normally reserved for outer space and particle accelerators, that sort of thing), you'd come just as far away from the center of mass of the planet as you started. So as long as your 'jump point' is higher up than your destination, you're fine. Just hop in, fly by rock hotter than the surface of the sun, and then pray to gods you don't believe in that someone'll catch you so you don't start on your return trip too early.

However, I think the pesky rotation problem will do you in anyways. Linear velocity at the equator exceeds Mach 1.5; at the exact core it's essentially zero. Dropping down a hole does not magically rid you of that sideways momentum, so you will probably be getting a stone wedgie long before you even hit the mantle. You'd have to stick a rail guide along the side which, since frictionless unobtainium isn't yet in mass production and Hotblack Desiato has first dibs on the stuff anyway, would cause you to lose some of that precious inertia on the way down, thus requiring that you expend power getting yourself up the last bit.

Assuming that I were particularly interested in going to China in the first place, I'll just take a cruise, thank you very much.

Re:For the coming "hole to China" questions/jokes

so what you're saying is.. and stop me if I'm wrong here, is that if we can amass a very VERY big exposition, we might blow a hole into the corona, dropping an improved version of these probes onto the surface of the sun, and create a beowolf cluster.. where we can cause siesmic dusiturbances which will (previosuly worked out) distribute photons in a pattern out of the corona (sun spots, flare distribution) which we will be able to reduce back into a readable data stream for data collection of the suns various environmental variables, and anonymously share not proman nudies.

is that what you ewre suggesting?

pm

Actually discussing proposition

Wow, 108 comments and I have yet to find one that discusses the proposition in any detail. (maybe all those fluid dynamics equations are as foreign to other slashdotters as they are to me :-) At any rate, I just finished reading the annotated paper, and I've got a few comments and questions:

1) Why, instead of using all this iron buisiness, don't we simply use a radioactive ball of goo? This would mean that the whole blob could be a lot smaller as you wouldn't have to worry about maintaining the heat - the radioactivity can do that for you! As well, given that melting point increases proportionally to pressure, and that the pressure in near the earth's core is extremely high, you don't have to worry about getting the iron hot enough to not worry about that. The guy writing the paper does mention the possibility of using nuclear, but he doesn't give any good reason why not.

2) Nice quote - "The correct application of this energy to open up a crack and the technological challenge of emplacing the iron should be much less challenging than the manhattan project." He does realize how difficult the manhatten project was, doesn't he?

3) He mentions that the hole would not completely close up behind the probe (NB - this would not cause a volcano, for reasons he points out, mostly due to tube size and geometry). Why is this the case? does some of the matter get combusted into a gas and escape out the chimney? or is there something else here that makes this not violate the conservation of matter? On another thought, would it be possible to lower a second probe down this chimney?!

4) The sensor package he discusses would look for temperature, pressure, trace + major elements, and electrical conductivity, etc. I can understand the pressure bit, but wouldn't the temperature and element sensors only be sensing the iron casing that the probe was injected with? unless he has some other method of sensing these things at some distance away from the probe I don't see how this is possible (maybe trace elements mixed with iron on the way down, but the experimental error in this would be huge). On another note, using the nuclear probe proposal in point 1, could it be possible to moderate the nuclear reaction and thus stop the probe for a bit, do some sensoring (whatever that may be, and I know I made that word up) and geology, then start up again? Also, this would be valuable for point 5...

5) He mentions that we don't know much about working with seismic waves. Wouldn't all this iron buisiness and the fact that its fluid potentially cause problems with the seismic signal? (like distortion, etc) Given that we haven't done much encoding/modulating, and transmitting of data using seismic waves, it might be a good idea to perfect this first. The only other option I could see would be emitting a constant signal and watching how it varies as the probe descends, and then extrapolating this for data (of course, then you don't get the juicy data at the probe itself).

There's more I could think of, but I do want to get this out, and I've got other things I should be doing. All the same, the article was an interesting read and stimulated the brain cells fairly well, even if it is completely impossible!

Blob of Iron? More like a slashdotted server

Guess they won't need to find a blob of iron.
The slashdotting the server will receive ought to help melt it and the floor beneath it.

Off goes the server, down, down, down ...

A wireless probe?

They've found a way to get a wireless probe to connect from the middle of a molten ball of iron deep in the center of the earth, but I still can't get my cellphone to work in the subway.

The big question is -

Won't that disturb the people who live inside the earth? They may be aliens, but they have rights, too.

Totally ignoring the *real* problem

"made out of material which won't melt or dissolve in the iron"

I'd be more worried about the device being able to withstand that pressure. I fail to see how surrounding the probe with molten iron (or any other fluid, for that matter) will prevent the weight of the planet from squishing it like a bug. Or does he plan on violating the laws of physics at the same time?

Um, hello?

We already have tons of data concerning the nature of the Earth's core. Duh. There was a documentary shot on this very subject sometime in the sixties; it showed the center of the Earth to be a rather tropical, oceanic/tropical place, where dinosaurs still roamed free on land. Big, sail-backed dinosaurs: that's all there is at the center of the Earth. This iron-ball thing sounds like a waste of time.

One big problem

Won't making a crack this big in the Earths surface let all the gravity out ?

Re:One big problem

Don't worry, the increased solar radiation from global warming should stuff it all back in.

Great idea. It should work.

Firstly the probe will have to have all its parts be heat resistant, else should have an internal cooling method, and not just one of those Duron fans. And then the probes net density should be the same as the molten iron, so it doesnt float over it and touch the lava. Better yet it should have a way to adjust its own density, maybe eject some ballasts. Since most electronics are less dense than iron, to balance it, the probe should have material that has more density. I wonder if lead would do, or should we try Uranium.

I think the biggest problem will be the earths crust. Where can we find or drill a hole large enough vertically straight?? Hawaii?? Mount Fuji should be a better place but do we really want to drill a hole in that given its history?

And finally the idea that most of the space under the crust is molten mantle is still just a theory. Maybe 100 meters down the iron will just sit on another mass of rock that just happens to be there. And I dont know how will it find and go through cracks. If like water its allowed to drain, it will spread thin enough to damage the probe, so LOTS and LOTS of molten iron should be used on a vertical shaft like mount fuji.

I think radio waves of the right freq can travel within the mantle, so we could have large satellite dishes pointed into the ground. Heck we could even send bombs to China. Designer earthquakes!

And Everyone Thought

Andy Rooney was nuts [cbsnews.com]..

Sounds like...

... the opening scenes of a Jerry Bruckheimer film.

Data? What data?

As the probe falls, it sends data back using seismic signals

What kind of information about its surroundings could the probe pick up from inside all that molten iron?

Re:You were only supposed to blow the bloody doors

"and the gravitational fields of the earth are currently in the process of reversal"

Gravitational fields reversing? What, can we expect to start falling into the sky any day now?

Re:isn't this a bit risky?

Probably not.

The Earth has three layers:
* The crust (outermost)
* The Mantle (middle)
* The core (innermost)

The Mantle is mostly viscous liquid. The blast would be diffused into the liquid. Considering how much heat energy is in the magma at any given moment, a nuclear blast will have a negligable effect.

Volcanos are caused by magma (the top layer of the Mantle) seeping out of a crack in the crust. Blasting the core would not affect the crust at all.

The crust is separated into plates called tectonic plates that "float" on the Mantle.
Most earthquakes are caused by slipping in the tectonic plates.

Again, since the blast's energy will be negligable to the energy in the mantle, so there will be little flucuation in the mantle's energy to cause waves in the mantle.

Re:isn't this a bit risky?

Actually, the mantle is not liquid. It is crystalline solid, and is furthermore subdivided in to sub-layers based on seismic properties. (The core and crust are also subdivided in to additional layers, but that's another comment for another day...) If you managed to dig a hole down in to the mantle, then climbed down there, you could break a piece off with a rock hammer (based on the mineral assemblage it would be an attractive translucent green, perhaps with some brilliant green specks of chrome diopside, and black pyroxene grains -- depending on where in the mantle you are).

One part of the mantle, the asthenosphere, has a tiny amount of melted rock due to the pressure & temperature regime at this (100 - 200 km) depth, but melt is only on the order of 1% of the material here -- it just sort of coats and lubricates the mineral grains. The asthenosphere has little effective strength compared to the geodynamic forces it encounters, but it's far from liquid.

As long as I'm here: no, magma is not the top layer of the mantle, and furthermore a lot of magma does not have a mantle source (although a lot of magma does depend on mantle processes).

The rest of the mantle is believed to deform plastically, but it is not a liquid. It is composed of coherent solid crystals. This is very hot rock, but it is also under extreme pressure, and the crystalline phases that exist here are stable. Over long periods of time this material deforms like stiff putty.

As for detonating a bomb in the mantle, if you managed to figure out some way to do so...Yes, it would create seismic waves just like a bomb not detonated in the mantle would. Let us review: the mantle is solid coherent rock. But then again it's not as if that is even relevant because sound waves are very effectively transmitted through liquids as well as solids. That's why depth charges are used to kill submarines. Granted, shear waves do not pass through liquids, but pressure waves do. NOTE: unlike water, shear waves do pass through the mantle because the mantle is solid.

Seismic waves are received every day at seismometers around the world, originating from earthquakes all over our planet. Much of what we know about the deep earth has been inferred using these seismic waves. Again, the point is sound moves very readily through the solid mantle.

You did manage to get one thing right: plates do float on the mantle in every sense of the word. Continents in particular are just low density scum floating on a sea of high density mantle rocks.

You were also on the right track in regard to earthquakes occurring in plates, but I should add that earthquakes do not typically occur in the mantle because mantle rocks are so hot and under such high pressure, that when stressed they shear and deform plastically rather than fracturing and causing an earthquake. This property doesn't, however, prevent the propogation of earthquake waves through the mantle (see above), nor does it prevent the creation of earthquake waves when the hypothetical bomb causes a large and rapid change in the localized pressure regime.

- Anonymous Coward