With Planetary Resource’s plans to mine asteroids for metals, we look at facts and science fiction of such a feat.
Toward the end of April, Seattle-based Planetary Resources Inc. went public with its mission: to mine asteroids. A private enterprise with some heavyweight investors, the company marks the participation of yet another private enterprise in the latest iteration of the space race—that to be run and sponsored by private, as opposed to public, money.
So, apart from what we’ve all been told by the players themselves, are there any issues that may, perhaps, require a bit more attention?
Do Asteroids Really Contain Those PGMs?
What are asteroids anyway? Perhaps a good way of understanding asteroids is briefly to compare and contrast them with comets. NASA has a great comet fact sheet. Some of the most salient shared and individual characteristics are the following:
The most important characteristic of asteroids, in this context, is their composition; in particular not only that they can be made of metals, but also that they can contain water. Most asteroids fall into three main categories:
- C-type (Carbonaceous): According to NASA (back in 1996), such asteroids included more than 75 percent of those then known. Apparently with a composition like that of the sun, they lack “hydrogen, helium, and other volatiles.” In addition, they can contain water. (In 2010, two research teams discovered water on the asteroids 65 Cybele and 24 Themis, both C-type bodies.)
- S-type (Silicaceous): These asteroids accounted for 17 percent of known asteroids. They are composed of “metallic iron mixed with iron- and magnesium-silicates” and, sometimes nickel.
- M-type (Metallic): Included “many of the rest of” then-known asteroids. They are composed mainly of metallic iron, and nickel.
Although it might be useful to have alternative sources of nickel, iron and magnesium, it is the possible presence of the platinum group metals (PGMs), in particular, in asteroids that is really making them attractive to prospective space miners.