Could asteroids be mined in the future?
Possibly. Asteroids contain water, metals and other resources, and companies and space agencies have studied mining them, but no asteroid has yet been mined.
Asteroids contain materials that could be valuable, either on Earth or for use in space.
Water. Carbonaceous asteroids contain water locked in clay minerals, sometimes up to about 10 per cent by weight. In space, water could be used for drinking, for growing plants and, split into hydrogen and oxygen, for rocket fuel. Using water from asteroids could make long space missions cheaper.
Metals. Iron meteorites show that some asteroids contain iron, nickel and cobalt, along with small amounts of platinum-group metals. M-type asteroids, such as 16 Psyche, may be rich in metal.
Challenges. - Distance and cost. Reaching and returning from asteroids is expensive. The largest asteroid samples returned so far weigh only about 122 grams, from Bennu. - Technology. Mining in microgravity, on loose rubble-pile surfaces, presents unique difficulties. - Economics. Bringing large amounts of metal to Earth could lower prices, reducing profits. Using materials in space may be more practical. - Law. The 1967 Outer Space Treaty forbids nations from claiming celestial bodies. Some countries, including the United States and Luxembourg, have passed laws allowing companies to own resources they extract, but the international legal position is debated.
Progress. Several companies were founded in the 2010s to pursue asteroid mining; some have closed. Space agencies continue to study using resources in space, especially on the Moon.
Science first. Missions such as Hayabusa2, OSIRIS-REx and Psyche are helping us understand what asteroids are made of, an essential first step for any future use.