Good morning ARSE-tralia, it’s time yet again to prod the thinktank of ARSE with your questions as we thrust Australia into the deep unknown…
Today’s question comes from Shaun in our illustrious Australian Space Society…
“Which planet in the solar system has the most valuable minerals/resource to be mined other than Earth?”
Well, travel is an issue, else we could talk about mining other galaxies.
The most important considerations for a space mine are location, location, location.
The surface of another planet is a terrible place to mine because whatever you produce will be stuck at the bottom of a gravity well. You might as well just mine Earth…
What about near-Earth asteroids?
Well, most of the asteroids are way out between Mars and Jupiter. They are frigidly cold, solar energy is very weak, and it is more than a year’s journey in each direction. So cross the asteroid belt off the list. So what about near-earth asteroids? Well, there are a few, but they are mostly rocky asteroids rather than metal.
But there are some metal asteroids close to the earth, and the most promising is (6178) 1986 DA. It is mostly iron - about 100 billion tonnes - but also contains about a billion tonnes of gold, platinum, iridium, and other precious metals. When we are ready to start mining in space, metallic near-earth asteroids are the most sensible place to start.
The Solar System’s Prominent Planets?
Just what minerals the other worlds have is a mystery. The gas giants are, of course, out of the running. Venus, by its very nature, is also out of the running. Both Mercury and Pluto are tiny planets located in extreme places…not likely either.
Likely, the smaller the world, the more mineral poor it is.
That leaves Mars. Mars is a small world that had some volcanic activity billions of years ago. It lacks a magnetic field which suggests it doesn’t have a lot of heavy elements, particularly, iron and nickel. Lacking volcanic activity for so long a time, it probably doesn’t have large amounts of heavy minerals near the surface and also lacking running water for billions of years, there would be little erosive effects to help make it accessible.
While Mars is the best bet, it is no gift. It is lethal to life in every way and lacks easy sources of larges amounts of energy necessary for heavy mining.
Still, the real answer to your question would have to be; there are no other planets in the Solar system that would be practical or feasible to mine for elements.
What about the Moon?
In my opinion, the short-range most profitable place off Earth to mine in the near future is on the Moon near the lunar south pole as it seems to have water ice.
The Moon has big enough gravity to make mining easy. Chop stuff up and it falls to the ground. The Moon has small enough gravity to make orbital launch using a mass driver easy. That makes the Moon the best starting point. Lots of aluminium, titanium and other lighter elements. Plenty of solar power and enough random elements to make the cells. Some buried water.
Once lunar mines exist and are launching materials to orbital factories, iron asteroids are next. The Moon has less iron so we’ll want those heavier metals. The big economic boom will use the Moon to establish the machinery to get the asteroid heavy metals back home.
As it has ice and probably other volatiles, that helps enormously in setting up a colony. You can near the south pole set up a number of solar power stations within ~ 160 odd km of the pole such that you will have solar power ~ 24/7 (because of rotation of the moon and being near the pole. The moon’s inclination of rotation with respect to the sun is 5.1 degrees. So going ~ 30.3 km covers 1 degree of arc. 5.1 degrees is 154.5 km or round up to 160 km on hills or crater rims and you can guarantee 24/7 power, make a part circle of about 160 km radius with ~ 3 or four power stations and you have 24/7 power and water and all the minerals the moon has to offer.
All a short 3-day flight from Earth.
That lets you set up a base with a lot of material resources on the moon to provide for further expeditions out.
The number one contender for mining is…
Earth. Our planet is a special case. Due to the collision with a Mars-sized body, Earth has more heavy elements than it ordinarily would while also being the most massive of the rocky planets. The Jupiter of its league, its gravitational pull likely got the lion's share of the good stuff in its neighbourhood.
Earth is also volcanically active and nearly completely molten except for a razor-thin crust. Consequently, valuable, heavy elements are constantly brought to or near the surface. Abundant liquid water then erodes the overburden away making it easy to mine.
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