Look back in history and you will see that the motivation behind huge investments in exploration and transportation has been the need for resources. The American settlers headed west in their search of gold, oil and timber, and the Europeans headed east along the Silk Road and the spice trade routes. Now, a company based in Seattle, Washington, plans to head away from Earth and into space in search of the precious resources to be found within the thousands of asteroids existing in orbits relatively close to our planet.
The company, Planetary Resources Inc, founded by Eric Anderson and Peter Diamandis, has attracted a group of investors and advisers including Eric Schmidt and Larry Page of Google, and film director James Cameron. The ultimate goal is to exploit the valuable resources which asteroids can offer, and the biggest challenge is to achieve this within a budget which makes the whole project cost effective.
Why is asteroid mining such an exciting proposition?
Asteroids contain an abundance of valuable resources including platinum, gold, iron, nickel, rare earth metals and water. At present around 9,000 known asteroids travelling in an orbit close to Earth’s have been identified, with around 1,000 new ones being discovered each year, all of which as easy to reach as the moon. And because they are much smaller than the moon the lower gravitational force will mean that landing and taking off will be less of a problem. Unlike the Earth, heavier metals are distributed evenly throughout an asteroid’s mass rather than closer to the core, and as an added attraction the presence of these materials will often be found in much higher concentrations than on Earth. For instance, it has been estimated that a one kilometer diameter asteroid could contain about 7,500 tons of platinum, worth more than $150 billion.
Rare Earth metals
Despite their name, rare earth metals are fairly common in the Earth’s crust, but the fact that they are so widely scattered makes them difficult to mine. So finding a viable means of harvesting them from space will potentially be a highly profitable business. Added to this, around 95% of the world’s supply of rare earth metals presently comes from China, who have decided to cut back on their exports in order to accommodate their own rapidly expanding industrial needs.
Platinum group metals
Platinum group metals do not occur naturally in the Earth’s crust, but are present due to earlier meteorite impacts. A meteorite is simply a piece of asteroid which has fallen to Earth, so the study of meteorites gives geologists a good idea of the most suitable types of asteroid to choose as candidates for mining.
Which are the most likely candidates?
The vast majority of asteroids are located in the region of our Solar System between Mars and Jupiter called the Asteroid Belt, or Main Belt. They range in size from around half a mile across to about 600 miles in diameter, and were created at the birth of the Solar System, 4.6 billion years ago. To put it into perspective, the total mass of all known asteroids, more than half a million in all, is about 4% that of the moon. Due to the gravitational influence of Jupiter some have orbits which carry them close to Earth, in which case they are called Near Earth Objects, or Near Earth Asteroids. And these are the asteroids which Planetary Resources intend to study and ultimately exploit.
How are asteroids classified?
In broad terms there are three classifications of asteroid based on their composition:
- C-type, which are the most common, are carbonaceous, and consist of clay and silicate rocks. They exist furthest from the Sun, and so have been least altered by heat, meaning that they are the most ancient. Due to the fact that some have never even reached temperatures above 50°C, it is estimated they can contain up to 22% water.
- S-type or silaceous asteroids are made up primarily of stony materials and nickel-iron. They inhabit the inner Asteroid Belt.
- M-type, or metallic, are made up mostly of nickel-iron, and are found in the middle region of the Asteroid Belt.
What are the challenges?
The greatest challenge to Planetary Resources is to build commercially available robotic spacecraft which are at least an order of magnitude cheaper than those currently in use. Unlike governments, failure can be accepted during the development process, and the goal is to build the crafts in an assembly line fashion in order to drive down costs. The project will be carried out in stages, with the first phase already underway, and it is hoped that by the middle of next decade mankind will be reaping the benefits of the abundant resources that asteroids have to offer.
- The Arkyd Series 100 – Leo Space Telescope. Due for launch within the next two years, its job will be to analyse NEOs in order to determine the most likely candidates for future exploitation. Techniques such as spectroscopy and radar technology will be used to determine properties such as the asteroid’s chemical composition, orbit, rotation, size, shape and metal concentration. Due to its relatively low cost and its potential usefulness in a vast number of applications, the Leo will be of interest to the scientist and private citizen alike. The sale of these crafts will therefore enable Planetary Resources to gain revenue in order to achieve its future objectives.
- The Arkyd Series 200 – Interceptor. The intention is for this craft to hitch a ride on a geostationary satellite in order to analyse asteroids at more close quarters. Future advancements in micro-propulsion and imaging techniques will be utilised to enable the craft to get close enough to obtain high resolution data. Two or more Interceptors working together will ensure that the data is collected as quickly and efficiently as possible.
- The Arkyd Series 300 – Rendezvous Prospector. This phase of the project will involve focusing on asteroids much deeper in space. Laser communication technology will be used to determine shape, rotation, density, and surface and sub-surface composition. The Prospector’s capability as a low cost interplanetary spacecraft should also attract customers such as NASA and other scientific establishments.
After all the prospecting has taken place, the most exciting phase of the project can then be carried out, the actual mining of the precious resources. Initially the most important resource available in space will be water. Apart from being essential to sustain life, it can also be split into hydrogen and oxygen to create fuel to enable spacecraft to travel further into space. This would allow us to build refuelling stations in order to reach more distant asteroids and aid future manned exploration of the solar system. For this reason the first targeted asteroids will most likely be C-type.
What methods will be used?
The technology needed to carry out the mining process has not yet been developed, but possible methods have been suggested. A device similar to a snow blower, anchored to the surface, could be used to collect loose rubble by using a spinning blade to fling the material through a chute and into a high-strength bag. Many of the mining methods will be similar to those used on Earth, and will consist of drilling, blasting, cutting and crushing. Extraction of individual materials, depending upon their properties, will be achieved by either chemical or physical means. Water can be extracted by heating the solid material, capturing the vapour and then distilling it; electrolysis of molten silicates would produce oxygen, iron and other alloys; and a method called the Mond process could be used to extract nickel. As well as being used for creating industrial wealth on Earth, these raw materials could also be used to actually build structures in space. Dozens of other processes are being considered, and meteorites are the perfect objects to experiment with on Earth.
The idea of landing a robotic craft onto an asteroid in order to extract its precious materials may at first seem the stuff of science fiction. But the more scientists get to grips with the technology necessary to achieve it, the more likely it is that science fiction will soon become science fact.