The US Air Force spaceplane X-37B is being readied for its third Orbital Test Vehicle flight (OTV-3) on October 25. The vessel, which will launch aboard an Atlas-Centaur rocket, carries a classified payload like its predecessors.
“As with many other advanced technology test programs, some details of the mission and test requirements are classified or sensitive,” said Air Force spokesperson Maj. Tracy Bunko. “The focus of the program remains on vehicle capabilities and proving the utility and cost effectiveness of a reusable spacecraft.”
The X-37B being deployed for this flight is the same as conducted OTV-1 in 2010 with a total flight time of 224 days. A second unit blew past its designed flight time of 270 days in 2012, ultimately spending 468 days in space. The Air Force has not specified the target flight duration of OTV-3, although the focus of this test seems to be on the reusability of the vessel more than its stamina. “As with previous X-37B OTV flights, the mission duration is driven by completion of the test objectives rather than any specific date,” said Bunko.
The X-37B’s design is largely based on the retired Space Shuttle, which it resembles. There are rumors that the OTV-3 might end with X-37B touching down on the Space Shuttle’s runway at Kennedy Space Center. The craft is entirely robotic, originally designed to deploy from the shuttle itself before NASA passed the project off to first DARPA then the Air Force. X-37B was built by Boeing’s Phantom Works division. The craft retains the essence of its original mission, though: to test equipment and perform experiments in a space environment over a long time period, then return the test materials to Earth for examination. This is a capability that has not been available since the retirement of the shuttle made it difficult to transport large items from the International Space Station. That capability will be partially restored with the upcoming October 7 resupply mission of the SpaceX Dragon capsule.
A derivative of the X-37B, called the X-37C, was announced to be in the works at the Space 2011 conference nearly one year ago. The X-37C is also based on the shuttle profile, but would include crew as well as cargo capacity. No news has been published on the X-37C since the original announcement.
Below, the June 16 2012 landing of the OTV-2 at Vendenberg Air Force Base in California: