A commercial space transportation industry is growing rapidly. Private companies are competing for launch contracts for government, military and private customers, and prices are falling quickly. NASA is turning its human spaceflight attention from low Earth orbit to the Moon and beyond. Several companies are even thinking about building settlements on Mars.
All of these activities will require physical infrastructure in the form of spacecraft, space stations, refueling depots, and so on, but where will this hardware be built?
Initially, of course, on Earth – but it is energy-intensive and costly to lift anything out of Earth’s deep gravity well and into space: a rough gauge is about 10 kilograms of propellant for every kilogram of material; when one factors in the mass of spacecraft equipment such as propellant tanks, engines, communications, etc. the requirement is closer to 30 kilograms of propellant per kilogram of useful cargo. Would it make more sense to build things in space in the first place?
There are several advantages to doing this: 1. materials in space are abundant, 2. lower gravity means moving material from origin to destination in space requires far less energy than moving it from the Earth’s surface, and 3. many materials on Earth are running out, and mining damages the environment; both these problems would be solved if materials are mined in space.
A cosmic cornucopia
More than 12,000 near Earth asteroids have been discovered within easy reach of the Earth-Moon system, and it is estimated that more than 2 million asteroids may exist in orbits reasonably close to Earth. Many of these are rich in metals such as iron and nickel, and possibly precious metals like platinum. Others are endowed with water ice or other “volatiles” like ammonia or methane. All probably have rocky materials containing silicon, aluminum and oxygen.
It is estimated that every element available in the Earth’s crust is also present in asteroids, and possibly in higher concentrations since heavier elements on such a light body as an asteroid do not sink to the core as they do on Earth.
In November 2015, the U.S. Congress passed – and President Obama signed – the Commercial Space Launch Competitiveness Act, making it legal for U.S. companies to appropriate materials in space for commercial purposes. (It also uses the term “commercial space transportation industry” to describe these activities.)
This landmark legislation firmly opens the door to commercial space mining, paving the way for growth of commercial space activities.
Building infrastructure in space
Extracting pure metals from a metal-rich asteroid appears to be straightforward in space. The Mond process uses carbon monoxide to extract pure nickel and iron from asteroid material. The resulting product is a liquid that can easily be separated from other material, and the pure metal recovered by mild heating.
The carbon monoxide can be recycled indefinitely to extract more metal. The metal, which can be recovered as a powder, can then be fed to a 3D printer to fabricate parts of any desired shape.
3D printing has already been demonstrated in a zero gravity environment of the International Space Station, and recently a space mining company demonstrated the first 3D-printed object made with meteorite material. With a bit more effort, other metals such as aluminum can probably be recovered, opening the door to lightweight materials and alloys needed to build a wide variety of structures in space.
The promise of low-cost access to space
Even if complex machinery cannot be fabricated in space, many massive parts probably can. With a suitable assembly environment (perhaps inside a spinning spacecraft to simulate the effects of gravity, which might make assembly easier), either run by tele-operated robots or actual humans, one can imagine large structures being built in orbit.
The tremendous mass savings of such an endeavor could make space transportation much less expensive. Together with in-space propellant depots supplied from off-Earth resources, reusable Earth-to-orbit launch capability on Earth currently being pioneered by several companies, and a sufficient supply of raw materials from asteroids, the cost of space access could approach the cost of energy required to lift a person into orbit, which in the long term might be as little as 20,000 US dollars. Water, oxygen, and even food could be grown in space.
An ecological boon on Earth
Space mining could become so cost-effective that mines on Earth would shut down, along with their attendant pollution problems. In space there are no sensitive ecosystems to pollute. Though we should still be careful about generating toxic hazards in space, in principle it is easier to segregate pollution away from human activities, and there is vastly more room in space to put everything, unlike on Earth.
With sufficiently low-cost materials from space, we could ban all terrestrial mining, and focus instead on ecological restoration, relegating extractive industries to the heavens.
Asteroid mining: Turning threats into opportunities
The technology for asteroid mining shares much in common with detecting and diverting asteroid threats to Earth. The impact of a large (1 kilometer) asteroid could cause severe climate impacts globally. While large asteroids are easier to find and track, we are currently limited by our ability to detect threats from smaller asteroids (100 to 300 meters) that could still cause tremendous destruction if they impact cities on Earth.
Better detection equipment – probably space-based – will be needed, along with techniques to move their orbits enough to avert the threat. A timely example is the 27 million-ton asteroid Apophis that will pass with 30,000 km of Earth – below the orbits of geostationary satellites – in 2029, and may impact Earth in 2036 without intervention. Fortunately, we can leverage this technology to identify asteroids of high economic value, and even move their orbits to allow for the safe return of material to the Earth-Moon environment.
Thus, money spent on planetary protection could in principle be self-financed, if the material from some asteroids are recoverable and sold at profit on Earth or in orbit.
What advances do you think space manufacturing could engender? Please share your thoughts in the comment section.
Please note that this article expresses the opinions of the author and does not reflect the views of Move Forward.