After a decade of development, the Air Force plans later this month the X-37B — a robotic spacecraft resembling a small space shuttle to conduct technology tests in orbit and then glide home to a California runway.

The ultimate purpose of the X-37B Orbital Test Vehicle and details about the craft, which has been passed between several government agencies, however, remain largely a mystery as it is prepared for launch April 19 from Cape Canaveral, Fla.

The X-37B, an adaptation of NASA and Boeing's old that started in 1999 (as a 120%-scaled derivative of ), is nearly , with a 14-foot, 11-inch wingspan. It could be used for intelligence gathering or delivering small satellites. For now, the Air Force says, the program objectives are "space experimentation, risk reduction and … development [of] reusable space vehicle technologies."

Although the length of the mission has yet to be determined the same Air Force spokesperson has said the vehicle has a requirement to be in-orbit for .