How valuable are asteroids?
There are millions of pieces of rock, known as asteroids, flying around our solar system.
But there are plans afoot to make use of these outer space fliers - and it sounds more like science fiction than science fact.
A group of billionaires in America want to get precious materials like water and even gold out of them.
It might mean space ships could stop on an asteroid to refuel, like an outer-space petrol station.
Leah has been to the University of Manchester to find out how it's possible, and if it really could happen.