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I was wondering would a planetary drill be possible? The drill should go inside the planet on one side and exit on the other.
Would that kind of a drill be possible on Earth and if not on what kind of planet would it be possible? Could it be possible with the technology we have today and if not what kind of future technology would we need?

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  • $\begingroup$ no. the borehole would be crushed. Also, i'm pretty sure that question already has an answer, although i can't find it at the moment. $\endgroup$ – Burki Jun 29 '17 at 9:21
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    $\begingroup$ I recommend reading reddit.com/r/askscience/comments/35dwyh/… $\endgroup$ – Raditz_35 Jun 29 '17 at 9:21
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    $\begingroup$ Welcome to WorldBuilding plexus! Interesting question. Are we talking about current day technology or at least near-future technology? Please edit your question to say something about the technological level that we should assume to answer your question. If you haven't done so already please take the tour and visit the help center to learn more about the site. Have fun! $\endgroup$ – Sec SE - clear Monica's name Jun 29 '17 at 9:22
  • $\begingroup$ Also the following question might be useful for you: Extending the Kola superdeep borehole and highly related (close to duplicate, but focusing on a single planet, not a general question for a possible to use planet) Drilling a tunnel into the core of Enceladus $\endgroup$ – Sec SE - clear Monica's name Jun 29 '17 at 9:27
  • $\begingroup$ That question does have some things answered, but what technology (future) would resolve the problems this drill had? $\endgroup$ – Plexus Jun 29 '17 at 9:39
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When drilling through a planet, one has to face two main issues:

  • Increasing pressures while going deeper down
  • Increasing temperatures while going deeper down

The increasing pressure will tend to crush the hole, and will have the side effect of turning each piece of material released by the drilling into a grenate when the pressure is released. One could coat the walls of the drilled hole with a resistent material, kind of a steel or concrete pipe, but with the increasing pressure the thickness of this coating would increase dramatically.

The increasing temperature will make any material useless for drilling, either by making it too plastic or making heat management problematic. To make thing worse, it would also weaken the hole walls.

The only way I see to make this problems negligible is to shrink the body you want to drill. In Kola drill hole we managed to reach 12 km below the surface. That size is comparable with the diameter of some asteroid or comet out there (with the wild assumption we can use the same technology we used in Kola also in the outer space).

We have already sent some drilling heads on other bodies, like Mars, the Moon and some comets. In all the cases they drilled a very shallow hole.

Main reason for this is the low power available to drive the drilling head. Even my flimsy home driller, with its 800 W, has more power available.

After the power issue, one has to keep in mind that drilling produces a lot of friction, and friction translates in heat. Heat dissipation on Earth is achieved by lubricating the head with some liquid, which also helps in taking away the debris from the drilling zone. Now we know that liquids in vacuum are not stable and tend to become gases, so a proper medium has to be developed.

Another aspect to keep in mind, on a 12 km diameter body, is that gravity is low. Therefore if the drilling arm pushes too hard while drilling, it will "simply" kick itself above the body. Proper anchoring needs to be in place, too.

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    $\begingroup$ Per the Rules of peer moderation "Don't answer a question that you voted to close." I want to ask why you answered a question that you think is a duplicate of Extending the Kola superdeep borehole. This looks very weird because you are on the hand saying that this question should be closed as it was answered before and on the other hand you are answering it yourself. Especially for new users it's confusing $\endgroup$ – Sec SE - clear Monica's name Jun 29 '17 at 10:19
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    $\begingroup$ @Secespitus I see your point, the OP edited the question after my remark. Therefore I am retracting my vote to close. $\endgroup$ – L.Dutch - Reinstate Monica Jun 29 '17 at 11:06
  • $\begingroup$ The heat problem could be avoided in a planet with a cold core. $\endgroup$ – ivbc Jun 30 '17 at 23:22
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See Tides of Light by Greg Benford.

Of course don't expect to be able to live on the planet afterward. If you can't find a convenient superstring a magnetically guided singularity would do the job. It would have to travel pole to pole and be travelling with sufficient velocity not to fall back to the centre of mass. And you would of course need to catch it on the other side.

This is engineering at the Kardashev type II or better level.

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This is not possible simply because earth isn't fully solid. If drill deep enough there will be magma and if you go deeper there are molten metal. You simply can't drill anything that's liquid as it will just fill the hole. Only way would be sliding a tube inside and drilling in that, but as I said - molten metals, that means anything you put in that will ... yes you guessed it MELT. So where could you drill a hole from one end to another? on something smaller that has cooled in center.

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  • $\begingroup$ You could dig from the US to China... $\endgroup$ – RonJohn Mar 11 '18 at 7:10

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