A favorite science fiction subject involves groups of humans taking excursions to the asteroid belt, in order to mine for various elements to send back to Earth for its burgeoning needs. The Expanse, a series of books and now a TV series by Daniel Abraham and Ty Franck (under the pen name S.A. Corey), feature large groups of colonists permanently occupying some of the largest asteroids in the belt, working to mine the other asteroids and perform other supporting tasks. Many feel that this is the logical future for Mankind, moving out to the belt to bring its vast resources back to Earth, and speculate that it’s only a matter of when for this benchmark of the future to happen.
I’ve pointed out before that a lot of science fiction is still based on 20th century (and older) notions, both romantic and historic; and the concept of industrial-scale mining efforts among the asteroids is one of those. Thanks to the realities of the 21st century, asteroid mining for resources has evolved from a when argument to an if argument.
In the past decades, scientists and engineers have developed two technologies that will soon directly impact the value and profit margins derived from mining. One of them, the most well-known so far, is 3-D printing: This system of building multi-faceted objects is already revolutionizing manufacturing and materials use. So far most 3-D printed products comprise one or two elements, but we are rapidly learning how to combine more elements to create much more useful objects and products. Engineers speculate that we’ll be able to build objects, molecule by molecule from multiple elements, fairly soon. Applying computer models are also showing us how to more efficiently build individual components, improving efficiency using less actual material. And that will mean a much more efficient use of materials, wasting much less and avoiding the use of other materials that are often used in fabrication that are not part of the finished product.
The other, less well-known development, is the ability to bombard atoms with subatomic particles to create new elements at the atomic level, also known as Nuclear Transmutation. Once the fictional realm of alchemists, modern scientists and engineers are learning how to bombard atomic elements using particle accelerators to change their states or create new elements. This marvel of a concept still has a ways to go to achieve bulk efficiency, but it has the potential to take almost any element and turn it into other elements. The possibility of applying this to waste materials and “recycling” them into new, useful elements, is also on the board, helping us to clear the incredible amount of waste products that are choking landfills and floating about our oceans. And using waste materials as raw materials will hopefully give the world the incentive to clean up as much of that material as possible for resell to new element processing.
So, within a few decades, we could see fully viable systems using existing and recycled old elements to reform them into useful materials at the atomic level; and passing those on to computer-aided 3-D printing systems to create new products more efficiently and with less material waste (see below)—in fact, any cast-off waste can probably be broken down and reused to create other elements and products on another line somewhere.
Without even resorting to actual calculations, we can expect an element-synthesizing and 3-D printing system will be much cheaper than the cost of lifting heavy manufacturing equipment, people and life support resources off of Earth with rockets; sending them all past Mars to create a sustainable habitat out of a large-ish asteroid (or bringing an entire sustaining habitat with them in the form of a giant city-satellite); working to mine the materials and sending those resources back to Earth.
To begin with, traveling from Earth to the nearest point of the asteroid belt is a journey of 254.5 million kilometers… more than six times the closest distance from Earth to Mars. If you compare present estimates of 300-day trips to get to Mars, you’re looking at maybe a 5-6 year trip to reach the asteroids. That’s a damned long way to push a lot of heavy equipment. And that’s assuming the elements desired happen to be adjacent to Earth’s shortest flight distance when you’re ready to go; if a particular asteroid is targeted, you might need to wait a number of years for that travel distance to close sufficiently, or risk doubling the length of your trip (10-12 years—helpful Steve). And if you plan to move from asteroid to asteroid, better bring or be able to synthesize plenty of fuel while out there… unless you plan to have Earth send you tanks of fuel and other supplies across 255 million kilometers every so often. Bottom line: We won’t be ready to take that trip for decades; in fact, we may need to wait until we can build a base on Mars to act as a depot or launch point, just to get us partway there.
Even if we optimized the asteroid-mining process as much as possible, sending only skeleton crews out there in smaller ships in order to supervise a 99% robotic mining and shipping system, we’re still looking at a much larger projected cost to go to the asteroids than to synthesize our own elements here. The only way to justify that cost would be if some element proves to be so valuable AND so hard to synthesize here on Earth that collecting it from asteroids makes up for the expense. And there aren’t likely to be many elements that will prove that valuable, especially as our abilities to re-synthesize elements improves over time.
So: By the time we’re ready to mount the first expeditions to the asteroids, the need to go may be past and gone.
We may still be able to learn many things from the asteroids; robotic probes should be sent to the belt to examine the asteroids and see what they can tell us about the early days of our Solar System or the universe at-large. Maybe we’ll even discover new elements that aren’t known or available on Earth, which might be useful for something, or are capable of being synthesized here once we know about them and their properties.
But the idea of traveling to the asteroids to mine and send materials to Earth is another romantic 20th century notion whose day is almost done. Thanks to the things we’ve learned so far in the 21st century, we are rapidly approaching the day when we can reliably say that we don’t need the minerals in the asteroid belt for Earth… because we can make them right here.