Riches in the Sky: The Promise of Asteroid Mining

Most people, when they think of the future of space exploration, imagine returning to the Moon and going to Mars, eventually to build settlements on those two worlds. But the real incentive that will drive humankind to spread beyond this planet may not necessarily lay on large, celestial bodies like the Moon or Mars. The real wealth to be had beyond the boundaries of this Earth may lay in the lay in the tiniest parts of the Solar System, in asteroids.

What Are Asteroids?

Asteroids are small bodies of rock, metal, and other materials, most of which reside in a belt between the orbits of Mars and Jupiter. The near-earth asteroids, which closely approach the earth, are classed as Atens, with orbits between the earth and the sun, Apollos, with orbits similar to that of the earth, and Amors, with orbits between the earth and Mars. There are two groups of asteroids, known as Trojans, which share the orbit of Jupiter. Centaurs are asteroids that have orbits in the outer solar system.

Asteroids are also classified by their composition. The majority of asteroids are classified as C-Type and have the same composition as the sun, but without the hydrogen. S-Type asteroids are composed of nickel-iron with some silicates are iron and magnesium. M-Type asteroids are entirely made of nickel-iron.

There are two theories of the origin of asteroids. Either they are material left over from the creation of the solar system or they are the result of a planet that at one time orbited between Mars and Jupiter and was destroyed when it ventured too close to Jupiter and was torn apart by its gravitational forces.

Scientists have identified about two hundred Earth approaching asteroids, that is to say bodies which intersect the orbit of the Earth at one time or another. These would be convenient targets for asteroid mining expeditions as they would be readily accessible from Earth, The downside is that such asteroids have been the cause of a number of mass extinctions when they have impacted on Earth, such as the asteroid that landed near the Yucatan sixty five or so million years ago and killed the dinosaurs.

Riches in the Sky

To get an idea of just how much wealth is to be had from asteroids, one can examine 3554 Amun, a mile wide lump of iron, nickel, cobalt, platinum, and other metals that has an orbit closely resembling that of Earth's. Though it is one of the smallest known metallic asteroids, 3554 Amun contains thirty times as much metal as has ever been mined by human beings in the history of Earth. It's value, at current prices and if mined slowly to keep commodity prices level, is estimated to be 20 trillion dollars.

Other types of asteroids can be sources of materials scientists call volatiles, namely oxygen, carbon, nitrogen, and so on that are necessary to sustain human life. These materials would make could export commodities for lunar and other settlements. Some have even envisioned mining comets, which are essentially lumps of frozen water and other materials, to feed the needs of space settlements.

How to Mine an Asteroid

A space ship proposing to mine an asteroid would immediately encounter one major problem. Most asteroids tumble at a great rate, complicating any mining operations. Rockets would have to be attached to the asteroid to slow the tumbling before mining could commence.

Since asteroids have little gravity to speak of, one would not so much land on an asteroid as dock with it. This would be accomplished with harpoon-like devices that would be attached to cables. The harpoons would penetrate the asteroid and the cables would winch the mining equipment to the asteroid.

There are two methods for mining an asteroid, roughly analogous to mining methods on Earth. These would be strip mining and shaft mining.

To strip mine an asteroid, a digging machine would slice into the surface using a blade. Because a large amount of loose material would result, some kind of canopy would have to be deployed to contain it and prevent it from interfering with the mining operations.

Shaft mining would involve digging a shaft into the asteroid and following the veins of valuable ore. Some kind of transportation device would have to be deployed to convey the mined ore from the end of the shaft to a processing facility.

Whatever method is used to extract material from an asteroid, some kind of habitat would have to be built nearby to sustain the human crew. While a great part of asteroid mining would be automated, humans will still have to be on hand for troubleshooting and maintenance. Once extracted, material will have to be transported, either to a lunar or Mars colony, or perhaps a micro gravity factory in Earth orbit, for processing and fabrication into useful products, building materials, and even consumables like oxygen and water.

The Economics of Asteroid Mining

It takes a low deltaV (i.e. the cost of changing velocity) to reach an near Earth asteroid from low Earth orbit or, say, the Moon as opposed to that required to travel from the Earth's surface to Earth orbit or the Moon. Hence mining asteroids and transporting the material to facilities in Earth orbit or on the Moon is an attractive alternative to bringing such from the Earth. This is especially true if one uses rocket fuel mined at the asteroid itself to return material.

What are the potential markets for materials mined from asteroids? Human settlements on the Moon or Mars could use a source of industrial materials (i.e. iron, silicon, etc) and consumables (i.e. water, oxygen, etc) that are readily accessible. Factories in low Earth orbit, manufacturing high value pharmaceuticals, semiconductors, ultra-pure crystals, and exotic alloys, would also be a potential market. Asteroid materials could be used for building large scale facilities in space, such as solar power stations. Some high valued material, such as platinum group metals, would be useful for applications on Earth, such as building hydrogen fuel cells.

Asteroid Mining and the Future of Space Exploration

Asteroid mining could be a key component in providing an economic incentive for space exploration. Thus far, people who have been advocates of space exploration have emphasize science or intangible benefits such as political prestige. But if it can be shown that there are economic benefits to space exploration, the creation of new products fueled by asteroid materials, say, and the facilitation of the human settlement of the Moon and Mars, then the arguments for investing money for space become so much more potent. Centuries ago, explorers went to the New World of the Americas for "God, glory, and gold." There are no aliens elsewhere in the Solar System to convert and we are in any case too enlightened to try. Glory, in the form of science or political prestige, may be insufficient in an era of budget deficits and Earthly concerns, to justify spending a lot of money on space exploration. But there is indeed gold in those hills flying in the heavens. And such may be the spur that takes humanity to the stars.