The unmanned X-37B spacecraft, also known as Orbital Test Vehicle-2 (OTV-2), glided back to Earth on autopilot, touching down at California’s Vandenberg Air Force Base at 5:48 a.m. PDT this morning. The landing brought to an end the X-37B program’s second-ever spaceflight, a mission that lasted more than 15 months with objectives that remain shrouded in secrecy.
The X-37B stayed in orbit for 469 days this time, more than doubling the 225 days its sister ship, OTV-1, spent in space last year on the program’s maiden flight. Officials at Vandenberg said the spacecraft conducted “on-orbit experiments” during its mission.
“With the retirement of the space shuttle fleet, the X-37B OTV program brings a singular capability to space technology development,” said X-37B program manager Lt. Col. Tom McIntyre in today’s statement. “The return capability allows the Air Force to test new technologies without the same risk commitment faced by other programs. ”
Exactly what the spacecraft, which is built by Boeing, was doing up there for so long is a secret. The details of the X-37B’s mission, which is overseen by the Air Force’s Rapid Capabilities Office, are classified, as is its payload.
This secrecy has led to some speculation, especially online and abroad, that the X-37B could be a space weapon of some sort — perhaps a sophisticated satellite-killer. Some experts also suspect that the vehicle may be an orbital spy platform.
The Air Force, however, has worked to tamp down such speculation, stressing repeatedly that the X-37B isn’t doing anything nefarious hundreds of miles above the Earth’s surface.
“This is a test vehicle to prove the materials and capabilities, to put experiments in space and bring them back and check out the technologies,” Richard McKinney, the Air Force’s deputy undersecretary for space programs, said shortly after OTV-1 landed in December 2010.
“My words to others who might read anything else into that is, ‘Just listen to what we’re telling you,'” McKinney added. “This is, pure and simple, a test vehicle so we can prove technologies and capabilities.”
The X-37B looks a bit like NASA’s recently retired space shuttle, but it’s far smaller. The X-37B is about 29 feet (8.8 meters) long and 15 feet (4.5 m) wide, with a payload bay about the size of a pickup truck bed. Two X-37B vehicles could fit inside the payload bay of a space shuttle.
While the X-37B currently flies only hush-hush missions for the Defense Department, its spaceflight role may be expanded in the future.
In its current state, the vehicle could fly cargo missions to the International Space Station, docking to the orbiting outpost’s common berthing port, Boeing officials have said.
Boeing is also looking into building a larger variant of the spacecraft called the X-37C, which could ferry up to six astronauts to the space station. The X-37C would be 65 to 80 percent bigger than the X-37B.