# Can we build a machine that will function in lava? **URL:** \ **Category:** Factual Questions\ **Created:** [June 23, 2009, 5:49pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742 "2009-06-23T17:49:30Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [June 24, 2009, 11:27pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/21 "2009-06-24T23:27:01Z")
I feel certain that you could build a machine that works in lava. But you’re going about it all wrong by imagining it would be some room temperature-workable device fitted out to work at really high temperatures. good engineering design is something that takes advantage of the ambient circumstances and works in harmony with them, rather than trying to work in spite of them. Don’t view the high-temperature , “sticky” lava as an obstacle, but as a design element.Take advantage of things you only have in an under-lava situation. I’m not suree what those would be =-- there hasn’t been a lot of study of materials at that temperature, under those circumstances. I could certainly build a lever out of refractory materials – that qualifies as a “machine” by the most basic definition. But I’ll bet there are devices that could be found that work well under such extreme circumstances that wouldn’t work at all under normal temperatures. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [June 24, 2009, 11:44pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/22 "2009-06-24T23:44:34Z")
> [@omgzebras](#): > > For refrigeration to work the system needs to be able to radiate it’s stored up heat into the outside environment. Heat transfers from the higher temperature coolant or heatsink into the lower temperature air or water, thus cooling the system. In this case though, the outside environment is lava which is so much hotter than anything the machine will be producing that the heat transfer would go the wrong way. Instead of radiating heat your coolant or heatsink will absorb it and make your problem even worse. You can pump “heat” in any direction. It only becomes a problem when the environment you are pumping “into” is so hot your AC components melt. The hotter the dumping environment and the cooler you want the cool environment, the harder it becomes, but lava isnt so hot IMO that its beyond the realm of “doable”. If the machine required interior parts that had to work in much more reasonable temps, it would probably have to be pretty large, given that volume (energy storage) goes up as sized cubed, while surface area (heat “leaking” in) goes as size squared. The bigger you make it, the better your volume to surface area ratio gets. You need the energy storage to keep pumping the heat out. With lava outside you are going to be doing some serious heat pumping. I suspect if it had to work for any significant length of time, the thing would have to be nuclear powered. ---
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [June 25, 2009, 12:04am UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/23 "2009-06-25T00:04:21Z")
Finally, here is that stupid paper! > [@](#): > > [**Planetary science: Mission to Earth’s core — a modest proposal**](http://www.nature.com/nature/journal/v423/n6937/full/423239a.html?lang=en) > > _Nature_ **423** , 239-240 (15 May 2003) | doi:10.1038/423239a > David J. Stevenson > > Not science fiction, but a technically feasible plan to probe our planet’s inner workings. > > Planetary missions have enhanced our understanding of the Solar System and how planets work, but no comparable exploratory effort has been directed towards the Earth’s interior, where equally fascinating scientific issues are waiting to be investigated. Here I propose a scheme for a mission to the Earth’s core, in which a small communication probe would be conveyed in a huge volume of liquid-iron alloy migrating down to the core along a crack that is propagating under the action of gravity. The grapefruit-sized probe would transmit its findings back to the surface using high-frequency seismic waves sensed by a ground-coupled wave detector. The probe should take about a week to reach the core, and the minimum mass of molten iron required would be 10^8–10^10 kg — or roughly between an hour and a week of Earth’s total iron-foundry production. And [the National Geographic version](http://news.nationalgeographic.com/news/2003/05/0514_030514_earthcore.html) And [a diagrammed version by the author](http://web.gps.caltech.edu/faculty/stevenson/coremission/) ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [June 25, 2009, 12:07am UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/24 "2009-06-25T00:07:36Z")
> [@CalMeacham](#): > > I feel certain that you could build a machine that works in lava… But you’re going about it all wrong by imagining it would be some room temperature-workable device fitted out to work at really high temperatures. > good engineering design is something that takes advantage of the ambient circumstances and works in harmony with them, rather than trying to work in spite of them. Don’t view the high-temperature , “sticky” lava as an obstacle, but as a design element.Take advantage of things you only have in an under-lava situation. Precisely. Can lava itself be a lubricant? What is its properties? Is it corrosive? There are different types of lava. Could you channel low-melting-point lava in a high-melting-point rock? Foam the high-melting-point rock as an insulator for your testbed lava container? ---
**Author:** ![JonathanTheRed](https://avatars.discourse-cdn.com/v4/letter/j/8491ac/32.png) [@JonathanTheRed](https://boards.straightdope.com/u/JonathanTheRed)\ **Post date:** [June 25, 2009, 12:14am UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/25 "2009-06-25T00:14:41Z")
The Orbiter of the Space Shuttle is subject to 3000F temperatures during reentry, quite a bit hotter than lava, and not only do its systems remain functional, its human occupants are well protected. But then again, the Orbiter isn’t subject to those temperatures for very _long_, so I don’t know how relevant this is. ---
**Author:** ![Sapo](https://avatars.discourse-cdn.com/v4/letter/s/ec9cab/32.png) [@Sapo](https://boards.straightdope.com/u/Sapo)\ **Post date:** [June 25, 2009, 6:02pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/26 "2009-06-25T18:02:39Z")
> [@alterego](#): > > Finally, here is that stupid paper! > And [the National Geographic version](http://news.nationalgeographic.com/news/2003/05/0514_030514_earthcore.html) > > And [a diagrammed version by the author](http://web.gps.caltech.edu/faculty/stevenson/coremission/) Simply amazing. Is the idea sound? Has anyone else come forward to say it would or would not work? How do you melt a million tons of iron at the same time? ---
**Author:** ![Terraplane](https://avatars.discourse-cdn.com/v4/letter/t/74df32/32.png) [@Terraplane](https://boards.straightdope.com/u/Terraplane)\ **Post date:** [June 25, 2009, 6:59pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/27 "2009-06-25T18:59:47Z")
> [@billfish678](#): > > You can pump “heat” in any direction. It only becomes a problem when the environment you are pumping “into” is so hot your AC components melt. The hotter the dumping environment and the cooler you want the cool environment, the harder it becomes, but lava isnt so hot IMO that its beyond the realm of “doable”. How would that work? The only way your AC components are going to be able to cool the system is if they have someplace to dissipate the heat energy they’ve absorbed from the system. Nothing in the machine is going to be hotter than the lava, how can you use the lava to cool it down? ---
**Author:** ![alterego](https://avatars.discourse-cdn.com/v4/letter/a/6bbea6/32.png) [@alterego](https://boards.straightdope.com/u/alterego)\ **Post date:** [June 25, 2009, 7:15pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/28 "2009-06-25T19:15:16Z")
> [@Sapo](#): > > Simply amazing. Is the idea sound? Has anyone else come forward to say it would or would not work? How do you melt a million tons of iron at the same time? The upper end of the scale is 11 million tons of iron and I have no idea how you could melt that much iron. Not only that, but I have no idea how long the crack in the earth’s crust after the nuclear detonation lasts. So you have to worry about transporting the molten iron to the blast site post haste. Nonetheless I think it’s a really friggin cool idea. It’s made more interesting by the recent theory that the earth’s magnetic field could be magnetohydrodynamic - i.e., created by the oceans and not a molten core. ---
**Author:** ![threemae](https://avatars.discourse-cdn.com/v4/letter/t/5f9b8f/32.png) [@threemae](https://boards.straightdope.com/u/threemae)\ **Post date:** [June 25, 2009, 8:16pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/29 "2009-06-25T20:16:28Z")
> [@omgzebras](#): > > Nothing in the machine is going to be hotter than the lava, how can you use the lava to cool it down? Granted, lava is hot, but it isn’t _that_ hot. Wikipedia suggests typical temperatures between 900-1600 degrees Celsius. Warm, but I suspect not completely beyond the realms of our materials sciences abilities. Certainly it isn’t beyond the realm of theoretical possibility. For instance, tungsten has a melting temperature of around 3410 °C. Carbon’s about 4000 °C. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [June 25, 2009, 8:56pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/30 "2009-06-25T20:56:13Z")
> [@omgzebras](#): > > How would that work? The only way your AC components are going to be able to cool the system is if they have someplace to dissipate the heat energy they’ve absorbed from the system. Nothing in the machine is going to be hotter than the lava, how can you use the lava to cool it down? Extremely simple AC theory answer here. You can make “parts of the machine” as hot as you want till they melt. Other answers here have shown some materials melt at temps significantly hotter than “lava”. You make something extemely hot, use the lava to cool it down to just lava hot and viola! you’ve dumped heat INTO the lava, which was the whole purpose. If it was a gas, in tubing say, then you let that gas expand in volume and drop in pressure and it cools way down. Now you have a cool gas to cool things down. I’ve done a lot of handwaving here, but thats the gist of it. ---
**Author:** ![billfish678](https://avatars.discourse-cdn.com/v4/letter/b/7bcc69/32.png) [@billfish678](https://boards.straightdope.com/u/billfish678)\ **Post date:** [June 25, 2009, 8:58pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/31 "2009-06-25T20:58:01Z")
> [@alterego](#): > > And [a diagrammed version by the author](http://web.gps.caltech.edu/faculty/stevenson/coremission/) LOL that has got to set some sort of record for cool idea / crappy diagram ratio. ---
**Author:** ![Frylock](https://avatars.discourse-cdn.com/v4/letter/f/ce7236/32.png) [@Frylock](https://boards.straightdope.com/u/Frylock)\ **Post date:** [June 25, 2009, 9:56pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/32 "2009-06-25T21:56:48Z")
> [@billfish678](#): > > LOL > > that has got to set some sort of record for cool idea / crappy diagram ratio. > [@](#): > > It is not to scale! 😛 ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [June 25, 2009, 10:19pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/33 "2009-06-25T22:19:00Z")
> [@](#): > > If the machine required interior parts that had to work in much more reasonable temps, it would probably have to be pretty large, given that volume (energy storage) goes up as sized cubed, while surface area (heat “leaking” in) goes as size squared. The bigger you make it, the better your volume to surface area ratio gets. You need the energy storage to keep pumping the heat out. With lava outside you are going to be doing some serious heat pumping. > > I suspect if it had to work for any significant length of time, the thing would have to be nuclear powered. Remember, you’ll have to deal not only with heat leaking in from outside, but waste heat from whatever you’re using to power your probe. And if your power supply technology is in any way based on a heat engine (as most are, including nuclear reactors) then the hot end of your engine (your reactor core, in this case) is going to have to be significantly hotter than the magma outside. I think it’d be much more practical to design the thing with a consumable supply of some high-heat-capacity material (a big block of ice, in the simplest design) and just plan your missions to be short enough that you don’t use it up. ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [June 26, 2009, 2:56am UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/34 "2009-06-26T02:56:18Z")
> [@alterego](#): > > Finally, here is that stupid paper! > And [the National Geographic version](http://news.nationalgeographic.com/news/2003/05/0514_030514_earthcore.html) > > And [a diagrammed version by the author](http://web.gps.caltech.edu/faculty/stevenson/coremission/) A million tonnes of molten iron, eh? I wonder what the probe would be made of. And how would it sense passing chemical compositions if it was in the midst of all that iron? And what would power it? Fascinating. I’d be keeping an eye out for unexpected volcanic eruptions near the launch site though. ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [June 26, 2009, 3:00am UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/35 "2009-06-26T03:00:36Z")
> [@](#): > > Most carbonatite lavas have low eruption temperatures, **between 500 and 600 degrees Centigrade** (compared with \>1100 degrees Centigrate for basaltic lavas). [http://www.geology.sdsu.edu/how\_volcanoes\_work/Unusual%20lava.html](http://www.geology.sdsu.edu/how_volcanoes_work/Unusual%20lava.html) No sweat. ---
**Author:** ![rapidone](https://avatars.discourse-cdn.com/v4/letter/r/85e7bf/32.png) [@rapidone](https://boards.straightdope.com/u/rapidone)\ **Post date:** [January 6, 2011, 12:37pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/36 "2011-01-06T12:37:42Z")
Heat transfer can be achieved with superheated steam which can easily be increased to well above any material melting point but let’s say 100C above the immediate lava temp outside transferred through say tungsten pipes and outer skin so below the working temp of the final heat pump stages. Such a heat pump would require several stages and a lot of power, so nuclear reactor for source sounds about right and the later heat transfer stages would require some very exotic pumps. Clever insulation would direct the heat efficiently, maybe foam ceramics etc so the living/control area could be kept to 25C. The sub would need several skins for the temp and pressure but could be pressurised to reduce the need for massive hull strength, but if a robotic submarine this could be made much cheaper and smaller, with internal temp at say 100C but notably the pressure could made very high using say a water filled sub to counter the vast pressures as you go deeper. Controlling the pressure to match outside would be done by hydraulics and electronic control. As the pressure mounts however this would be more problematic than the control of temperature, as you are looking at pressures of 1.5 million atmospheres which will crush any component with a flaw in it. At the very least a few thousand atmospheres would be a starting point. The molten lava will also be very difficult to travel through, so the tractive effort of tank tracks, an elaborate drill or the like would also be required. The way a mole digs through soil would be a start with material from the front being passed to the back. This sort of robo lava sub is no doubt possible but would be a highly integrated machine with several inter dependent systems working to the limits of design. The project would be similar to the problems encountered by space travel and significantly more difficult than deep sea technology. Only the US, China and Russia would have the money and tech to pull this off but I guess a lot depends on what you’d use this device for? ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [January 6, 2011, 12:56pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/37 "2011-01-06T12:56:54Z")
> [@rapidone](#): > > Heat transfer can be achieved with superheated steam which can easily be increased to well above any material melting point but let’s say 100C above the immediate lava temp outside transferred through say tungsten pipes and outer skin so below the working temp of the final heat pump stages. Where are you dumping heat to? You have to have a cold temperature reservoir into which to reject excess heat. Stranger ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [January 6, 2011, 1:28pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/38 "2011-01-06T13:28:48Z")
You dump the heat into the lava. You just have to pump the heat into the cooling coils really really fast. The cooling coils would be hotter than the lava. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [January 6, 2011, 5:17pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/39 "2011-01-06T17:17:38Z")
> [@WarmNPrickly](#): > > You dump the heat into the lava. You just have to pump the heat into the cooling coils really really fast. The cooling coils would be hotter than the lava. So they’re made of unobtainium? As for pumping the incoming heat back out to the same reservoir, permit me to introduce you to my favorite physical law, the second law of thermodynamics, as typified by [this diagram](http://upload.wikimedia.org/wikipedia/commons/2/22/Carnot_heat_engine_2.svg). Even if you are doing negative work (putting energy into the system) you still have to have a lower temperature reservoir to dump heat to, and in fact in doing the work in a closed system (pumping and/or compressing the fluid) you are adding more heat to the system, which is self-defeating. You could of course carry your heat sink around with you–say, a supercooled block of lead–but that means that your reservoir is a very finite resource, while the energy flux from even “cool” molten lava is going to be enormous. It just isn’t feasible to cool the hull of a “lava submarine” (or rather “subterran”) via convective cooling. Stranger ---
**Author:** ![WarmNPrickly](https://avatars.discourse-cdn.com/v4/letter/w/d78d45/32.png) [@WarmNPrickly](https://boards.straightdope.com/u/WarmNPrickly)\ **Post date:** [January 6, 2011, 6:56pm UTC](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742/40 "2011-01-06T18:56:02Z")
I didn’t say I could engineer the damned thing, but it doesn’t violate the second law of thermodynamics any more than your air conditioner that takes heat from your house and dumps it into the hotter outdoors. Does this require five nuclear reactors a million miles of coil and nonexistent materials? Probably, but the second law simply means that it will take a lot of energy to move that heat, not that it can’t be done. [Previous page](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742.md?page=1) [Next page](https://boards.straightdope.com/t/can-we-build-a-machine-that-will-function-in-lava/500742.md?page=3)