A next-generation military space plane which can launch satellites into orbit every day is a step closer.
The US military plans to build a reusable space plane which can fly cheaply and quickly into space to deposit vital defence satellites.
The Defense Advanced Research Projects Agency is now welcoming design proposals for the revolutionary vessel.
Currently, space vehicles are not fully reusable and need to undergo time-consuming safety checks in between flights.
But it is hoped the Experimental Spaceplane (XS-1) project will produce a space plane capable of travelling to space 10 times in 10 days at a cost of just $5 million (£3.5m) a time.