Excursion to the Center of the Earth

Maggie Koerth-Baker is a guest blogger on Boing Boing. A freelance science and health journalist, Maggie lives in Minneapolis, brain dumps on Twitter, and writes quite often for mental_floss magazine.

I really need to start keeping a list of my favorite ludicrous plans, if for no other reason than so I can say, "This is my absolute favorite ludicrous plan," and not have it be just hyperbole. That said, I've been working for mental_floss in some capacity since I graduated college in 2004. In that time, I have read about a lot of grandiose, impractical ideas. But this is one I go back to when I'm having a bad day and need cheering up.

In 2003, CalTech planetary scientist David J. Stevenson proposed a way to send a probe down into the depths of the Earth. Published in Nature, "Modest Proposal: Mission to the Earth's Core" laid out a detailed plan for inter-Earth investigation--it was brilliant, theoretically possible (or so I'm told) and only briefly mistaken for an April Fool's joke. For your convenience, I have taken the liberty of breaking Stevenson's proposal down into four steps.

Step 1: Get $10 billion. Surprisingly, this is not the hardest part.

Step 2: Find a nation willing to take one for the team, by letting you blast a 984-foot-deep hole in their country with a nuclear bomb.

Step 3: Pour in enough molten iron to fill your new crevasse. Hopefully, gravity should now kick in, pulling the heavy metal toward the center of the Earth and lengthening your original hole at a rate of about 10 miles per hour. At that speed, your iron river should reach the Earth's core in a week or so. And, naysayers, never fear. According to Dr. Stevenson's calculations, high pressures below ground would reseal the earth after the iron passed by--preventing any awkward uncloseable chasms.

Step 4: Before the flow of iron gets moving too fast, toss in a probe. For maximum effectiveness, said probe should be able to withstand temperatures surpassing 3000° Fahrenheit and pressures 1000 times greater than the bottom of the deepest ocean. It also has to have a strong enough signal that it can reach the center of the Earth and still transmit some data back to you. As you go through the bidding process, do remember that you get what you pay for. And, in case American manufacturing has lost its edge, let's go with an unmanned probe. Better safe than sorry.

Image is courtesy Michael Rogalski.


  1. oh, theres a Morlock on the escalator
    and he’s goin’ down, down, down
    There’s a Morlock on the escalator
    hope he stays out of my end of town…

  2. Every time I think: “This is the worst idea ever” I’m quickly humbled by human ingenuity. Ingenuity that works in both directions apparently.

    Is there a major reason to throw a probe into the center of the Earth? I know we’re not 100% sure what its like, but I have a reasonable assumption, based on cursory observation that there’s a lot of 1) heat and 2) heat affected things. What more is there to know?

  3. That’s surprisingly feasible…

    Maybe use cabling meant for deep ocean runs as your communication pipe. It’s already meant for high pressures (well, not THIS high, but at least it’s a good starting point), and available in lengths measuring hundreds to thousands of miles.

    Now all you need is to design a probe that can withstand ludicrous temperatures and pressures, yet contains instrumentation to gather interesting information.

  4. if the idea is to find out what is inside, just steer a NEO into collision with Earth and have stand-off satellite probes analyze the debris.

  5. Why don’t we just grind the entire planet into slurry and then run the slurry through a spectrometer?

  6. How do they propose to keep the molten iron molten for the entire trip?

    It also has to have a strong enough signal that it can reach the center of the Earth and still transmit some data back to you.

    This is one of the parts that gives me the giggles. What the heck kind of signal were they thinking of? If it’s radio, we can basically just barely get an Ultra Low Frequency radio signal through water… veeery sloooowly… getting a signal through just the crust (at potentially 50km or more thickness) strikes me as a little unrealistic.

    I’d almost say a sonic signal would be a more realistic option, except that it would basically involve setting off explosives big enough for the shockwave to be detected clearly at the more-or-less-surface, and you’d have to do it over and over again to convey any kind of data. So you need lots explosives that can survive the environment, powerful enough to reach the surface, and you’re setting them off repeatedly, under the crust in a more or less unknown environment.

    That approach sounds more like a mad scientists scheme to create a volcano than a communication method…

    Running a cable down would almost be plausible, except for the problem of getting any cable to survive the trip…

  7. A hole precisely 984 feet deep, eh?

    You usually get this sort of oddly precise number when someone (usually aside from the original author) does a unit conversion, and the original was a nice, hand-wavy round number.

    So let’s see, I’m assuming that Stevenson specified a 300-meter hole, and the individual summarizing it for us chose to americanize all the metric numbers.

    Understandable and very common, but still a little funny.

  8. I’m hoping the pitch to said potentailly accomodating country country goes a little like this:

    “Well, your excellency, first we plan to use a nuclear device to dig a 300m hole (yes, your Excellency, that is anout 384 feet, then we will pour in the molten iron – don’t worry, the earth’s own gravitational field will take over from there and…”

    “GUARDS! Seize him!”

  9. I know why that gnome is on the down escalator to hell, and it ain’t ‘cuz he’s a pre-Christian pagan symbol.

  10. QRSS can send data over miles of damp string. Does a physical probe really need to go there when remote sensing might do?

  11. To quote a line from the Broadway Show “Lil’ Abner” as spoken by Senator Jubilation T. Cornpone: “Your government is going to spend one million dollars to blow your home off the face of the earth. Now show your appreciation!”
    My favorite scientific fictions are those proposed for getting to the moon by Cyrano de bergerac as he plays a mad man and holds off the Count de Guiche so Roxanne can marry Christian.

  12. It almost sounds like Russia could do this. They have a vast land mass that is unpopulated in many areas, access to lots of iron, and experience with deep sea exploration.

    Now all they need is a reason.

    (also, as for the communication problem: Give the probe a powerful radioactive source and a lead shield thick enough to block it. put a hole in that shield. place another shield over the hole with an actuator that can move it quickly; use that actuator to create a binary stream of particles. Place a geiger counter at the surface. voila!)

  13. @urshrew #5 – I work with a few geochemists, and some guys have made a career out of trying to figure out exactly what’s going on in the earth’s core. They build giant machines with lasers and huge electromagnets and monstrous hot crushing chambers to try and simulate it.

    The idea is, among other things, to try and figure out the origins of the earth and how it and other planets (and by extension, the solar system) were formed, as well as trying to complete the picture when it comes to things like tectonics that are still not fully understood.

  14. The obvious choice for communication is a tachyon pulse emitter. Not only are tachyons unimpeded by small details like magma and physics, but the signals would arrive before we send the probe, obviating the need to build one.

    I look forward to Dr Stevensons instructable showing how one can be built by reconfiguring a common-or-garden phase rifle.

  15. Anyone else seen that movie “Crack in the World”?


    …I think I saw this on TV when I was a kid in the 80s. The premise presented via bullet points

    –>Scientists in love!
    –>Scientists cook up crazy idea to launch rocket into Earth’s crust
    –>Nobody likes this idea, except the scientists in love
    –>Crack forms around globe
    –>Same scientists try to “fix” problem using nukes
    –>Earth shatters in two
    –>Scientists in love still alive to repopulate, er, half the Earth
    –>Cute chipmunk makes cameo to assure us all life will go on

    The good part: http://www.youtube.com/watch?v=8M00laK2U2Q

  16. The current New Scientist has in interesting article on USArray, a long running project to map the earth under the US using seismographs.

    “Having started off in California in 2004, it is now just east of the Rockies, covering a north-south swathe stretching from Montana’s border with Canada down past El Paso on the Texas-Mexico border. By 2013, it should have reached the north-east coast, and its mission end.”



  17. @WINGO

    Let me clarify, I totally get why scientists would want to know whats going on deep in the Earth, and I am a big fan of research for research sake. I think what I really want to know is why anyone needs to send a physical probe down there. Its like the joke of the Japanese scientists landing on the sun.

    (*punchline* They’re planning on doing it at night)

    It seems a better idea to use some sorta scanning technology to do it, instead of marring the Earth’s crust with nuclear explosions then send a physical probe deep into the Earth.

  18. This is probably one of those research missions that is worth waiting for new technologies to come along before attempting.

    It reminds me of the giant cannons that Jules Verne proposed to use for space exploration. Feasible or no, we were probably better off waiting for rocket technology to outpace gunpowder.

  19. While pouring the molten iron, add the tons of radioactive waste that we have laying around different parts of the U.S. (everywhere but Yuca Mountain). Quick and easy disposal to the molten core of the earth.


  20. Much earlier than Stevenson’s paper was the 1961 scheme of geophysicist William Manchester Adams to build a red-hot nuclear-powered torpedo to melt its way into the Earth’s mantle, drop a heavy weight, and float upwards to return geochemical samples.

    Something like this would be handy for reaching the oceans beneath the ice of Europa, too.

  21. On the other hand, these guys are worried that a deep-Earth probe might trigger our extinction (and that this may be an explanation why alien civilizations seem to be so scarce).

  22. Man-made holes in the Earth deeper than 300 meters (~984 feet) are common. Why the nuclear blast?

  23. Why blast a hole? Use an existing open-pit copper mine. Some of them are *way* larger than 984ft.

  24. some of you are missing the point. it’s not about how deep it is, but how much mass the iron will have: a 300 meter half-sphere-like molten iron filled crater will weigh about 50 million metric tonnes.

    anyway, even if it wasn’t so ridiculous, why should the iron stay in it’s shape?

  25. You don’t need to blast anything.

    Why not use this place?


    World’s biggest open pit mine- fill the whole damn thing with *hot molten iron* (Dr. Evil voice), and let it bore.

    That said, I’ve always wondered how deep humans could make a hole that would stay intact, and fill it with water to make the world’s deepest lake. And then bore a channel from the bottom of that to the sea, to let in all kinds of cool deepsea creatures to an inland location for surveying without all the wind up top you have on the open sea.

    I’m constantly thinking of weird ideas for tunnels like this, I’ve been reading too much Jules Verne.

    Would using molten iron work in smaller amounts for hole boring for subterranian homes? Say I get a big mix for thermite together, a few hundred/thousand pounds, could lighting that bore a reasonably deep hole for a cave home? I like this idea for using molten metal for drilling holes.

  26. Living in Minnesota, I prefer the lazy American mans route. Lets just hire cheap labor and make them build us an escalator. Then we can just ride down to the center of Earth. We can pay for the whole thing by letting it be sponsored by Sprint (Can you hear me now?) and selling retail space along the way (Starbucks, maybe The Hole in the Wall Bar).

  27. Well, the bit with the gnome is obvious. He’s heading to his job with the transit people. With his uncanny sense of rhythm, he keeps all the subways running on time.

    That’s right, he’s a Metro gnome.

  28. On a slightly different note, something was bothering me about this whole thing. So, I went and did some math.

    If the hole is essentially a hemisphere (a likely result of a nuclear blast, though not an efficient way to create a self-burrowing mass), you get:

    (4 * pi * (300^3)) / 6 = 56,548,667.8 (volume of hole in cubic meters)

    ((4 * pi * (300^3)) / 6) * 7874 = 4.4526421 × 10^11 (mass of iron in kilograms)

    (((4 * pi * (300^3)) / 6) * 7874) / 1000 = 445,264,210 tonnes

    ((((4 * pi * (300^3)) / 6) * 7874) / 1000) / 1,800,000 = 247.369006 years of global iron production

    If it is a large cylinder (size of JP Morgan Chase tower in Houston):

    305 * 120,774 = 36,836,070 cubic meters

    (305 * 120,774) * 7874 = 290,047,215,180 kg of iron

    ((305 * 120,774) * 7874) / 1000 = 290,047,215 tonnes of iron

    (((305 * 120,774) * 7874) / 1000) / 1,800,000 = 161.137342 years of production

    And for a “needle” of only 30 by 30 meters:

    (300 * 900 * 7.87400) / 1,800,000 = 1.1811 years of iron production

    (Note: the numbers for iron density and global iron production are from the ever-faithful Wikipedia, but I figure it’s close enough for these purposes.)

    That is just a ludicrously impossible amount of iron.

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