RocketAcademy writes "The Defense Advanced Research Projects Agency has launched a new program to develop a reusable first-stage launch vehicle. Experimental Spaceplane 1 (XS-1) would be capable of flying 10 times in 10 days, with a small ground crew, reaching speeds of Mach 10, and deploying a small upper stage to place a 3,000-pound satellite into orbit. The XS-1 program is complementary to the Air Force's Boeing X-37, which is a reusable upper stage. The X-37 is currently launched by an expendable Atlas rocket but could be launched by a vehicle derived from XS-1 in the future. Military planners have dreamed of a two-stage, fully reusable Military Spaceplane for several years, but funding has not materialized up to now."