Another company is set to enter the race to mine asteroids for precious resources.

Deep Space Industries says it wants to build an entire fleet of spacecraft which can travel to asteroids, land on them and harvest their rocks.

It will announce its plans at a 22 January event in Santa Monica, California.

It is said to be targeting softer, crumbly 'Near Earth' asteroids which it thinks could be mined relatively easily. It is thought that even a small asteroid could be worth billions in precious metals and other resources.

DSI joins another company, Planetary Resources, in the attempt to harvest minerals on asteroids.

Planetary Resources is backed by Eric Anderson, would has previously sent paying clients to the International Space Station, and investors including Eric Schmidt and Larry Page from Google, and advisor James Cameron.

The details of how these companies plan to harvest the asteroids is currently unclear.

Theories include the use of robots to 'snare' asteroids, which will then carry out the mining and automatically send resources to be picked up by other craft.

But others remain sceptical, pointing out that the astronomical cost of such a mission with current technology would make profitability unlikely.

Still not convinced it's worthwhile? Here's an infographic to convince you otherwise...