Why DARPA Is Pursuing the Reusable Military XS-1 Spaceplane

ORLANDO, Fla. – Here's a phrase that's not repeated everyday in the space community:

"You've heard Elon's comments … we want to go beyond that," Brad Tousley, the head of the tactical technology office at the Defense Advanced Research Projects Agency, said May 15.

Elon, of course, is Elon Musk, the optimistic, and some say visionary, founder of SpaceX with plans of eventually colonizing Mars. After landing three first-stage rockets, Musk has said SpaceX would inspect the rockets with plans to later re-fly most of them. [DARPA's XS-1 Military Space Plane Concept in Pictures]

Tousley oversees DARPA's space programs, which often handles the Defense Department's most difficult development challenges. He described the landing of first stage rockets by SpaceX and Blue Origin as "very, very impressive accomplishments."

But during a speech at the GEOINT 2016 conference here, Tousley said the agency's experimental spaceplane, known as XS-1, also has ambitious plans.