The Defense Advanced Research Projects Agency (DARPA) has partnered with Boeing to build its XS-1 hypersonic space plane.
The unmanned jet will fly to suborbital heights before deploying an expendable upper stage, which would carry a payload into low-Earth orbit.
The plane is then able to return to Earth and land like a conventional aircraft.
“The XS-1 would be neither a traditional aeroplane nor a conventional launch vehicle, but rather a combination of the two – with the goal of lowering launch costs by a factor of ten,” said DARPA.
DARPA and Boeing plan to conduct a flight test of the XS-1 space plane, flying it 10 times in 10 days, with initial engine tests set to start in 2019. Full test flights of the XS-1 will commence in 2020.