Art by Redline XIII
Asteroid mining is a sci-fi staple, right alongside faster-than-light travel, directed-energy weapons, and deflector shields. Tales of the earth’s demise may be premature, but prominent scientists are warning that we may run out of certain usable materials – the so-called rare earth minerals – sooner rather than later. The planet’s greatest concentration of these minerals is located in Bayan Obo in Mongolia, and those deposits may be depleted within 50 years at our current rate of consumption. Rare earths show up in everything from cars (especially electric ones) to smart phones to computers. Without them, we would be living in a very different world.
It should not surprise us, then, that some scientists are looking to the stars – or rather to the asteroids. Is asteroid mining the future for humanity? Will it turn out to be more trouble than it’s worth, or is it the only way for us to get the minerals we need?
There’s Not Much Out There
One big problem is that the total mass of the asteroid belt is small, only 4% of the mass of the moon, which is itself only 1% as massive as earth. Around a third of the belt’s mass is occupied by a single dwarf planet, called Ceres; only the remaining two-thirds is loose-floating rocks. If you divide that mass by the total amount of space occupied by the belt, you’ll find that the vast majority of that space is simply empty. If your only mental image of “asteroid belt” is from EVE, where the rocks are so close together that you can bounce off one while trying to orbit another, or if you immediately think The Empire Strikes Back, then you’ll need to re-calibrate.
So we have two problems at once here. The first problem is that there’s simply not much in the belt; the entire belt represents 0.04% of earth’s mass. Asteroids are not another earth-sized mother lode of resources just waiting to be tapped. The second problem is that the rocks themselves are so far apart; mining operations would have to be directed from a distance, and the mined ore transported to a central platform.
Asteroids Are Not Exceptionally Useful
What kinds of “mined ore” are we talking about, then? There are several different types of asteroids, each with a different composition, but the most common elements are iron, nickel, and silicon – not materials which are in any way rare on earth, and certainly not in a way that would justify the added cost (more on that in a minute) and effort of going to space to retrieve them.
It’s true that certain elements appear far more frequently in asteroids than on earth. This website, for instance, is positively giddy that platinum group metals are 400 to 500 times more common in asteroids. There are two problems with that giddiness, however. First, the platinum group are not rare earth metals, which are the ones we’re in the most immediate danger of running out of. They are useful enough in their own right, but they’re not exactly worth going to space for. Second, given the low mass of the asteroid belt relative to earth, even if platinum group metals are 400 times more common in the belt, that still means the whole belt only contains approximately 10% of earth’s reserves of those metals. That’s enough to last us for a few more years or possibly decades if we’re in danger of running out of platinum group metals at any point in the future, but again, it’s not as if the belt represents an earth-sized resource cache.
It’s Expensive to Send Stuff Into Space…
The single biggest problem, however, is just how expensive it is to get a mining platform into space to begin with. According to NASA, the current cost of launching one pound (0.4 kilograms) into space is approximately $10,000 USD. An average 150-pound (60 kg) human would cost $1,500,000 USD just to get them up there. Even if the mining systems of the future were fully automated and only consisted of robotic mining platforms, simply putting them in outer space would be an incredible cost.
Even if, as in our previous example, platinum group metals were 400 times more common on asteroids, how much would a company have to mine in order to turn a profit after launch expenses? (This is to say nothing of the other costs associated with a space mining operation, such as developing and building the robotic mining platforms themselves, or the cost of scouting various asteroids until they found one worth mining.) It’s impossible to answer that question, because the answer would hinge on how heavy the equipment was and therefore how much the company spent sending it into space in the first place. But the answer is “a whole heaping lot.”
A final operational cost is the sheer distance that the asteroid belt is from earth. The closest part of the belt is more than two hundred million miles (325,000,000 kilometers) away. Simply getting out to it will take the better part of a year, and the return trip will take most of another year – or possibly longer depending where earth is in its orbit around the sun by then. The travel time could be reduced by accelerating the rocket to a higher speed on its way out and using a stronger deceleration burn to slow it down when it arrives, but those kinds of burns would consume more fuel and thereby increase costs yet again. The mining company would have to decide whether to save money on a slower round trip or literally burn money in order to get their ore back to earth faster. Speaking of which…
…And Then Bring It Back
Once we have refined ore somewhere in space, now what? If the whole reason we’re contemplating asteroid mining in the first place is that we’re running out of certain materials on earth, then we obviously have to bring our haul back to earth. That adds yet another cost to the program, because it means we can’t simply launch an ore-gathering robot into space; we also have to send up a capsule, strong enough to survive re-entry into earth’s atmosphere, which can hold our loot.
The command module for the Apollo space capsule had a mass of 13,000 pounds (5,900 kilograms). In today’s money, that would be a cost of $130,000,000 USD to launch. However, its cargo capacity would be minimal for our purposes; it was literally just barely large enough to contain three adult astronauts. It wouldn’t be useful for bringing meaningful quantities of ore back into the atmosphere. We would need an even more massive ship for that – which means even higher launch costs. How much ore would we have to mine in order to offset an initial investment of potentially hundreds of millions of dollars?
With current technology, the prospect of asteroid mining seems to be a non-starter. However, no one knows what the future may hold. In the same article where NASA discussed launch costs, they mentioned that they were developing new technologies in the hopes of reducing launch costs to $100 USD per pound ($40 per kilogram), a hundred-fold reduction. That obviously changes the game substantially.
You may have heard it said that “necessity is the mother of invention.” As certain elements become increasingly rare on earth, that scarcity will drive up the price. Coupled with plummeting costs of getting a mining platform into space, we may soon reach a point where the cost of going to the belt is not much higher than the cost of digging for the last few specks of dysprosium left in the earth’s crust.
However, it remains important to keep in mind that the asteroid belt is largely empty. Locust fleets of mining ships parked bow-to-stern across a sky full of rocks will never be a thing in real life the way they are in EVE. Yet even if the future reality ends up being less romantic than our sci-fi dreams, asteroid mining may be yet another example of a sci-fi technology that made its way into the real world.