ABC News' Taylor Hom reports:

The U.S. military's mysterious X-37B space plane is headed back into the great beyond to do… whatever it does up there.

The X-37B is slated for its third launch in October, the Air Force said, but like its two orbital predecessors, the mission of the unmanned spacecraft remains shrouded in secrecy. The exact timing of the October spaceflight, dubbed Orbital Test Vechicle-3 or OTV-3, is also tentative.

"We are on track for the launch of the X-37B to occur next month, but the exact date of the launch is dependent on a number of factors including range conditions and weather," Air Force spokesperson Lt. Col . John Dorrian told ABC News. The 29-foot-long vehicle is set to launch aboard an Atlas 5 rocket from the Florida station of Cape Canaveral.

The pioneer voyage of the X-37B, called OTV-1, began in April of 2010 and lasted 225 days, eventually landing in December of the same year at the Vandenberg Air Force Base in California. The second orbit, OTV-2, touched down on the same base this past June following a record-breaking 469 day travel.

"For this third launch, while the vehicle is the same… we are considering landing it at NASA Kennedy Space Center in Florida instead of the previous base," said Dorrian. "We are looking to save money and make use of previous investments and infrastructure already available."

The mission for this small shuttle-like machine, developed by the U.S. Air Force and based on NASA's original X-37 design, remains largely classified. The secrecy surrounding the program, which is overseen by the Air Force's Rapid Capabilities Office, has attracted international attention from nations like China who have speculated a more aggressive intent.

"Industry analysts said the spacecraft could be a precursor to an orbiting weapon, capable of dropping bombs or disabling enemy satellites as it circles the globe," China's state-run Xinhua news agency wrote in June after OTV-2 concluded its mission.

Since the 2010 maiden flight, U.S. officials have continuously assured the world that the mission of the OTV series is non-nefarious "testing." For instance, the coming October mission will focus on testing the vehicle's capabilities as well the cost-effectiveness of the aircraft, Air Force spokesperson Maj. Tracy Bunko told SPACE.com, which first reported on the new mission

"One of the most promising aspects of the X-37B is it enables us to examine a payload system or technology in the environment in which it will perform its mission and inspect them when we bring them back to Earth," Bunko said. "Returning an experiment via the X-37B OTV enables detailed inspection and significantly better learning than can be achieved by remote telemetry alone."