The US Air Force’s reusable unmanned spacecraft, the X-37B, is scheduled to return to Earth this week. Although the exact day and time remains undetermined, preparations are underway at Vandenberg Air Force Base in California in anticipation of the arrival of the mini-shuttle as it ends its classified Orbital Test Vehicle mission 3 (OTV-3).

Secret space missions tend to be, as the term implies, secret, so it’s no surprise that the Air Force is playing its cards close to its chest about the third X-37B mission. The 29-ft (8.8-m) long, Boeing-built X-37B was launched on October 25, 2012 from Cape Canaveral, Florida and has spent over 600 days in space; breaking the previous orbital duration record for a reusable space vehicle set during a previous X-37B flight.

However, what it has been up to during all that time in orbit and why the OTV-3 mission lasted as long as it did remain closely guarded secrets. Despite this air of secrecy, the Air Force says that this does not apply to the day and time of the spacecraft’s landing. Rather, the uncertainty is due to technical issues and weather conditions. The X-37B is currently being monitored by the 30th Space Wing as the winged vehicle prepares to deorbit.

"Team Vandenberg stands ready to implement safe landing operations for the X-37B Orbital Test Vehicle, the third time for this unique mission," says Colonel Keith Baits, 30th Space Wing commander.

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