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My question is more science-based than hard sci-fi. Basically, I'm envisioning a scenario in which technology is advanced enough that life has spread through the solar system, and this mostly via self-replicating artificial intelligence.

There are all sorts of practical reasons why humans would avoid trying to build structures on, say, Mercury, because of the harsh conditions. I was considering, however, that isn't the planet a massive source of heavy metal material while also being open to easily collecting solar power? I'm envisioning AI structures keeping mostly under ground and in shelter. Gravity and atmosphere are not as much a concern as for biological life, but smart machines using drones to mine and fabricate what they need, while being able to easily collect direct solar power during the bright days.

Also, wouldn't fabricating system-traversing ships via AI be practical on Mercury due to the availability of energy, material, and lesser gravity [pull] to escape from?

EDIT [2019-12-25] ::

So many great answers. You guys have really given me fully-conceived theories that blow my mind. I cannot expound fully in comments below, so I'm putting this up here.

I'm conceiving of some world building of nearly self-realized robots which are fabricating essentially what they need and taking the time to do it. I chose Mercury and not Venus because the enormously thick atmosphere on Venus keeps the temperature so high (and doesn't cool down much at night) that it would be an obstacle (destructive, corrosive) for my robots.

Whereas, on Mercury, it planet is smaller and the the gravity penalty is also light. But I'm also envisioning that having some gravity is useful to AI bodies, as they still benefit from the simple functions of heat rising from endothermic reactions, and having lose and scattered material (from construction and mining) also continually falling back down to the ground. I'm also factoring that light planetary gravity would be useful for some basic hydraulic systems operating with gravity. (With liquid hydrogen stored in underground pools, perhaps?) The lack of much atmosphere means practically negligible pressure/friction/wind to interfere with operations, including ejecting craft into space travel via railgun.

I'm also curious about the placement of Mercury and its proximity to solar winds, and as to whether that would make mining/collecting solar elements any easier. (I guess 'close" to the sun is extremely relative. I want to incorporate hydrogen mining, but I'm fully aware I may need to do some hand-waving to make that a story point.)

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    $\begingroup$ Not an answer, but when I consider building a computer-planet, waste heat from computation is a much greater concern than power collection. Places like sub-surface Europa and Titan might make better places to build such structures as they're easy waste heat dumps. $\endgroup$ – BMF For Monica Dec 25 '19 at 23:36
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"It depends", as always.

For most things, the asteroid belt is the best place to start as there's a decent amount of mass that is trivially accessible (no super-deep mining needed) and in trivially shallow gravity wells (and so easy to move to anywhere else in the solar system). You can't get everything there, of course. Mercury is probably a good source for very heavy elements... actinides for example. Such things are likely to be increasingly rare as you move outsystem, and may not be readily available in the asteroid belt and may not be available at all. If you need uranium, Mercury might be a good place to go.

There are of course other in-system bodies which might also provide plenty of useful materials without the gravity well issue... the hypothetical Vulcan asteroids and other Apohele bodies, if large metallic examples can be found.

Conversely, other stuff like ice which is super useful for reaction mass or extracting fusion fuel from is much harder to come by in-system, so Mercury is most useful as a component of a larger industrial network. You can still make rockets fueled with regolith and regolith derived materials, and there's so much solar power available they'd still be OK.

I'm envisioning AI structures keeping mostly under ground and in shelter

As an alternative, consider orbital powersats and entire mobile mining facilities on the surface that operate on the nightside. The surface of mercury will have plenty of useful materials on it, and in the absense of locals to complain about the damage you can just stripmine the good stuff without having to make deep excavations. It depends on the scale of your AI's plans... you can't make a Dyson swarm this way in a sensible period of time, but if you wanted to do that you'd be engaging in more aggressive operations like increasing Mercury's spin rate via asteroid bombardment to make it easier to lift material off the surface in bulk...

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    $\begingroup$ you don't really need much in the way of rockets, mercury is small enough you can use electric rail launching or a space elevator using today's technology. which means you can use entirely solar power. $\endgroup$ – John Dec 24 '19 at 17:49
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    $\begingroup$ @John the alternative is needing 0 delta-V, and the ability to distribute millions of tonnes of materials without the need for massive infrastructure that is extremely hard to build and maintain on a planetary surface as hostile as Mercury. $\endgroup$ – Starfish Prime Dec 24 '19 at 18:16
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    $\begingroup$ No need to operate on the night side: There is no atmosphere on Mercury, so heat protection is as simple as a sun-shield. Just attach a solar panel at the end of a movable arm on the machines you want to keep cool and steer the arm to always keep the cool-loving machine in the shade. A surface that does not see the sun or the planet's surface can easily cool down to freezing temperatures during the day. You can do a lot of heat-engineering with simple directed/-able surfaces on this planet. $\endgroup$ – cmaster - reinstate monica Dec 24 '19 at 22:36
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    $\begingroup$ On the other hand, having a surface at 400°C and another at -100°C is excellent for harvesting some serious energy from the temperature gradient. You can actually use your sunshield to generate electricity with solar cells, simultaneously heating some working fluid which drives a generator, and is chilled down by heat radiators mounted on the same assembly. As I said: Fun for the heat-engineers! $\endgroup$ – cmaster - reinstate monica Dec 24 '19 at 22:57
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    $\begingroup$ Another idea: Collect the hot sand during the day (about 90 days long), and use it at night to provide energy. Or more precisely: Use two charges of sand. During the day, one is spread out for heating and collected in the evening to provide heat during the night. During the night, the other one is spread out for cooling and collected in the morning to provide a heat sink during the day. Your generators can thus work through the entire day/night cycle, providing electrical energy. It's really more a feature than a bug for AI based life forms... $\endgroup$ – cmaster - reinstate monica Dec 24 '19 at 23:01
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Yes and no.

Though Mercury is a vast source of mineable material, it is also deep within the solar gravity well. Therefore, it would be ideal for large construction projects harnessing solar energy(such as a Dyson sphere) or interstellar propulsion(such as proposed by Robert Forward).

For a Dyson sphere especially, Mercury could become the center of the construction operation, and would be completely disassembled to fabricate large numbers of Von Neumann self-replicating machines. These in turn could provide the energy and mass for a swarm of small mirrors within a few decades(one solid structure would be very unstable). This Kurzgesagt video describes the process in more detail.

However, turning our attention to AI vs. humans, it would be much simpler and less risky to automate any mining sites. Life support would be eliminated and equipment could simply be remotely monitored(although with a light delay of several minutes automated sequences would be a must). I agree with you; if you're going to set up this much infrastructure anyway, you might as well automate it in the first place. So that part of the question is; absolutely, yes.

The more questionable area would be launching from Mercury. Yes, there are practically infinite raw materials, but the Delta V would be in the tens of km/s, a figure unachievable by conventional propulsion. Perhaps a better idea would be to create huge mirrors, which could use the solar energy to direct lasers onto a "sail" similar to the Starshot program. Technology for this is already being tested, and it is not inconceivable that in system and interstellar travel could both be enabled.

TL;DR: Yes to both questions, but the second problem requires some unconventional methods.

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    $\begingroup$ The escape velocity of Mercury is under 5km/s, and so is trivially acheivable with a single stage rocket using present-day technology (though harvesting fuel might be awkward). The delta-V to get from a heliocentric orbit at Mercury's average radius to Earth's average radius is more like 18km/s which is tough for a chemical rocket but trivial for an electrical one, and there's lots of solar power available. Dawn launched 12 years ago and had 11km/s delta-V and was much further from the sun. $\endgroup$ – Starfish Prime Dec 24 '19 at 16:48
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    $\begingroup$ Why use rockets, at least for the first stage, mercury is small enough for rail launch or space elevators using existing materials. $\endgroup$ – John Dec 24 '19 at 17:53
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    $\begingroup$ @Starfish Prime True, but the OP described "system traversing" which might include the outer system. Also, there is plenty of available power at Mercury; I just suggested one possible use and chemical rockets could launch to orbit. I apologize for the misinterpretation. $\endgroup$ – Lelu Dec 24 '19 at 19:22
  • $\begingroup$ @StarfishPrime Thanks. I actually was thinking of the convenience of smaller craft able to be launched via electric rail, in fact. $\endgroup$ – dozTK421 Dec 24 '19 at 21:05
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Sure, mercury is a great place for any type of self-sufficient industry - human-managed or AI managed.

It is the only body in the solar system located in the energy-rich/dense environment and has plenty of matter.

It does not matter who rules there humans or AI but locating production or everything on the surface is not a good idea, as it restricts the uses of the place and does not open all its potential, but the same can be told basically for all other celestial bodies besides earth which is a biological library on its own.

So considering widespread and over the solar system as you mention - processes on mercury probably will be not so different from all other activities happening on the other celestial bodies - as an approach.

mining tail of production/industrial system on the surface and all the other stuff in the space where you have more flexibility and need fewer materials to counteract the challenges of creating a proper environment - for industry, for humans or AI brain functioning.

Considering the options for collection of energy provided by microgravity in space - basically, a foil floating in space can concentrate all the energy you want - placement of mercury in dense energy environment is not necessarily a huge benefit, considering the mass, fraction of the mass you need to have for energy handling compared to the rest of mass-energy investment you have to make for the production to work. But that big pile of materials - there isn't a long list of those in general - Mercury, Venus, Earth, Mars and respective moons of some of those. And next in the list Jupiter and its moons at 5a.u. - which also not a bad place despite it being 1/25 of the energy density of earth orbit, or about 1/166 of that in Mercury orbit.

So if I would be an AI and told to pick one out of Jupiter or Mercury - I would think for a second and probably choose Jupiter as it is more beneficial in long run - there are many factors - but because of fusion technologies as an example, or there are plenty of moons to prime the process and even at start the ~1/25(166) of sun energy density isn't such a slowdown factor.

The difference in efficiency between humans being capable to utilize Mercury and AI's being capable to do the same - the difference is negligible.

All that said Mercury is more valuable as a celestial body - not so much by other factors. In that sense low carbon content of it(not sure is it or not) maybe not a great factor as for AI's so as for humans - considering all the fancy properties we start to utilize and discover of those carbon-based materials including their use as semiconductors and all sorts of other applications. And considering carbon being in the list of the most abundant elements - carbon-based technology has great potential, so it would be naive to think if there is more Fe on mercury then it sure better for machines.

If you consider that self-replicating aspect of AI's then you have to think in terms of EROEI(energy return over energy invested), and mostly to the aspect of exponential growth associated with that AI situation, industrial system. They are not limited by factors of raising children and more produce flash the memory and go work thus cutting a corner here like 20-30 years. So if it does not happen under human supervision - it will go south quite fast, no matter where those will settle.

If you wish to choose not Earth and not Mars - I would suggest Venus - it maybe even a better place for AI's. It is a battery pack on its own (energy stored in the atmosphere) - but it may be a bit more challenging and more complex to think how things will enroll there - compared to mercury, so ..., but as AI escaping earth I would pick it to prime my conquering of the solar system if I do not wish to engage with humans early on. Then Jupiter, and then being a good humankind overlord then Mercury as a snack.

So to justify mercury selection you probably need to throw some additional reason in the basket - as like they intend to mine sun for materials(and energy) then it probably a better choice than Jupiter location. And thus widen and increase scope and scale of activity, so as technology advances - fast technological advancement of AI is probably one of the strong sides of those, so may make sense

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  • $\begingroup$ Thanks. Great information there. In my scenario of AI, think basically nearly self-realized robots which are fabricating essentially what they need and taking the time to do it. I chose Mercury and not Venus because of the enormously thick atmosphere on Venus keeps the temperature so high (and doesn't cool down much at night) that it would be very difficult to AI to operate on the surface at all. Whereas on Mercury, not only is it smaller and the gravity much less, but the lack of much atmosphere means practically negligible pressure/friction/wind as well to interfere with operations. $\endgroup$ – dozTK421 Dec 25 '19 at 18:30
  • $\begingroup$ @dozTK421 yes, thinking about venus operating is tricky, to begin with, but after some assumptions are digested it not that complex after all and you start to praise density of the atmosphere and its temperature. Floating tower 50-60 km high in such condigtions isn't such a big deal and it heat engine after that out of the box, and chiller for your ground troops which ten may dig and deliver. So floating is the key here. Similar stuff with Jupiter btw, if we go straight to it, it just a bigger battery with some specifics. Yes, vacuum makes some stuff easier, but as tech advances escaping eases $\endgroup$ – MolbOrg Dec 25 '19 at 19:51
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Another factor here:

You can build a base on Mercury that will be consistently at Earth-normal temperature without any climate control. The poles are always cold, pick your distance from the poles to get the desired average (figure the heat load of your equipment, you'll want a place cooler than your target temperature) and dig deep enough that it averages out. (That's not all that deep.)

And there's one advantage to mining Mercury--it's pretty much a planetary core--a good source of the heavier elements.

The gravity well is a considerable hindrance for getting stuff there, but it's not important for getting it home--linear motors can throw stuff off any airless world.

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The answer to your question is probably not. The materials to be found on Mercury can be much more easily and cheaply sourced on Earth. The cost of establishing any significant base on Mercury would be huge owing to the difficulty in traveling between Mercury and Earth (very large delta V).

That said if the effort were to be made then a base in a large crater near one of the poles of Mercury would provide plenty of energy, plenty of heat and plenty of cold in the permanent shade so humans could in principle live there, but in practice probably would not.

So an AI mining facility might be built on Mercury, but it would probably be cheaper and more efficient to build it elsewhere.

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  • $\begingroup$ In theory, if the AI was exiled from Earth, wouldn't Mercury make a large amount of sense for a self-sustaining AI? Because the other obvious choice I see would be the moon. $\endgroup$ – dozTK421 Dec 24 '19 at 3:54
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    $\begingroup$ If you are building on Earth, then yes, it would be cheaper to mine on Earth, which contains a lot of metals, especially if you can get at the mantle and core somehow. However, if you are trying to build stuff in space, such as a Dyson sphere, then it might be cheaper to mine Mercury. And Mercury does contain a lot of building materials, so if you have the capabilities to mine it, then you may as well do it, as the materials comprising it are fairly useless when accumulated in a dead space rock as they are now. $\endgroup$ – Richard Smith Dec 24 '19 at 4:38
  • $\begingroup$ @dozTK421 the moon is a bit resource-poor, really. The asteroid belt would be a much better choice. $\endgroup$ – Starfish Prime Dec 24 '19 at 16:49
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    $\begingroup$ @dozTK421 If the AI were exiled from Earth... well if it is better say that in the question. $\endgroup$ – Slarty Dec 24 '19 at 17:54
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    $\begingroup$ @Slarty the energy is cheap because the solar flux is high insystem. To do the same work outsystem you need to build vastly bigger solar arrays (or a nuclear fuel refining industry), things which are more complex to make than a sail. $\endgroup$ – Starfish Prime Dec 24 '19 at 19:48

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