Asteroids travelling in space are huge deposits of raw materials such as iron, copper, nickel, and cobalt. How should we go about acquiring them? This is a question to which scientists are already seeking answers. The most recent analyses conducted by researchers from WUST and the University of Oslo indicate where it is best to extract copper to make it economical and environmentally friendly.

The research was conducted jointly by Katarzyna Łuszczek, PhD, Eng. from WUST’s Faculty of Geoengineering, Mining, and Geology and Agata Krzesińska, PhD. from the University of Oslo (in Norway, she is on a postdoctoral placement; she defended her doctorate at the Polish Academy of Sciences in Wrocław). The paper discussing the results of their analyses will be published later this year in the Elsevier publishing house’s journal “Planetary and Space Science”. You can read its preliminary version here.

The article is also discussed in its latest newsletter by the Lunar and Planetary Institute – a renowned scientific organisation from Huston, supported by NASA and dealing with research into the Solar System. Once a week, LPI sends information to its subscribers about two groundbreaking, space-related studies whose results are about to be published. The analyses carried out by Dr Łuszczek and Dr Krzesińska were discussed in the early October issue of the newsletter.

"Shocked" asteroids

The researchers looked at H-type chondrites (also known as olivine-bronzite chondrites),  which belong to the class of ordinary chondrites, i.e. meteorites most often found on our planet. Their parent bodies, asteroids, are most numerous in the belt of asteroids between Mars and Jupiter orbits and among asteroids close to Earth. Chondrites from the H group have the highest content of metals, including copper, among all ordinary chondrites. They come from class S asteroids, which constitute as many as 17% of all asteroids (it is the second group in terms of numbers).

Dr Łuszczek and Dr Krzesińska measured their mass content of copper, i.e. the percentage of this element in the chondrites under study. In this way, they determined that asteroids S contain from 70 to 100 ppm (i.e. parts per million) of copper. It occurs most often in metallic grains in various phases of the iron-nickel alloy – that is, as an admixture. This means that its extraction would require the chemical dissolution of the grains to obtain copper itself,  which, especially in space conditions, would definitely increase costs and involve processes that are harmful to the local environment. However, the researchers have shown that there is a much better alternative.

– Much higher concentrations of copper are found in so-called shock darkened zones, i.e. the planetoid zones darkened as a result of a shock – says Dr Łuszczek. – It’s a source of native copper, a mineral rarely found on Earth that consists of almost pure copper. Its obtainment would only consist in mechanical processing.

As Dr Łuszczek explains, "darkened zones" are formed after collisions of planetoids when a shock wave passes through them. The energy (i.e. heat) released then causes the minerals in the asteroid to melt, as a result of which only pure copper remains. – Our research indicates that such a "shocked" asteroid can contain from 20 to 50% of copper in this form – stresses the scientist.

This discovery is all the more important because asteroids with “darkened zones” are not uncommon. On the contrary, they make up a large group among asteroids close to Earth.

– Our calculations show that the asteroid (6) Hebe alone, the sixth discovered asteroid from the asteroid belt, considered to be the parent body of the H type chondrites, has a copper resource that would probably satisfy our needs for thousands of years.  It has a diameter of 190 km and contains 1.39 x 1012 tonnes of copper, which means that only a two-centimetre thick outer layer of this asteroid contains as much copper as the earth's resources we know today. Of course, how to make the extraction of raw materials from outer space profitable is still problematic. We hope that our research will be one step towards solving this issue.