NASA is exploring whether passing asteroids could be turned into spaceships.
The outlandish idea is one of 13 ‘moonshot’ concepts – far-out ideas which may never become a reality – which are being explored.
The concept was devised by Jason Dunn, the co-founder of a firm that built a 3D printer on the International Space Station (ISS).
Mr Dunn believes that a mechanism could be developed to rendezvous with asteroids and turn them into autonomous spacecraft.
They could then be used to intercept objects that are set to collide with Earth, as well as other missions.
One of the other proposed projects looks at creating underwater drones that can dive inside icy moons through their volcanoes.
Another wants to use microbes to help recycle old spacecraft parts.
All of the concepts will be given a $100,000 grant from NASA to fund feasibility studies over the next nine months.
Those that show promise will be given a further $500,000 to develop their ideas over the next two years.
A similar contest last year saw NASA reward seven projects with the $500,000 development grant.
These included one which plans to send solar-powered robots to work on the surface of the moon.