Has the Air Force Landed Its Secret Space Plane?

An undated image released by the U.S. Air Force showing the X-37B spacecraft. (AP)

Whatever happened to the X-37B?

An unmanned vehicle with unknown intent, the X-37B has been orbiting the Earth for 173 days since its launch on April 22. Since its launch, the spaceship has captured the imagination of skywatchers, military experts and conspiracy theorists worldwide.

It has the payload of a medium-sized truck, so maybe its purpose is to ferry spy satellites into orbit. It can return to Earth after a single orbit, so perhaps it can pick said satellites up again after they've done their work and before they've been spotted by the enemy. Some say it may signal the start of the weaponization of space.

Whatever it is, it's an impressive piece of technology that at the very least has unparalleled capacity to generate headlines.

Now, for the second time since it launched, it's disappeared and the race is on once again to a) find it, then b) offer a plausible theory about what it's up to this time.

More On This...

Back in late July, the X-37B went AWOL for nearly two weeks off its regular flight path. When it was found, by amateur skywatcher Greg Roberts of Cape Town, South Africa, its new trajectory proved the shuttle was much more versatile than previously thought, with a "cross-range" wing set-up that may allow it to compensate for the slight turn in the Earth after a single orbit and land back on its original launch pad.

Now it's gone missing again, failing to pass over its regular flight path on October 7 and 9, according to UniverseToday. This time around, the alarm bells have started ringing much earlier, thanks to the extra scrutiny offered by how-to video guides and apps such as the Simple Satellite Tracker which popped up after its first disappearance.

Track satellites from within the U.S. and Canada

Yet despite the extra public surveillance, no one's been able to pick it up on a new flight path, leading to speculation that maybe this time around, the Air Force is preparing to land its experiment.

According to forum member "Slenke" at militaryphotos.net, its last known orbit "put it very close to Vandenberg AFB," one of the two sites expected to receive the X-37B. The other is Edwards Air Force Base, a second base also in in California.

The X-37B's solar array allows it to stay aloft for 270 days, but even top brass at the U.S. Air Force can't -. or won't .- say when it will land again.

“In all honesty, we don’t know when it’s coming back,” Air Force spokesman Gary Payton told reporters when it was launched. At that time, the main issue concerning the shuttle's makers was what kind of condition it would land in and whether it would be fit for reuse within a practical, although unspecified, timeframe.

According to the Pentagon, a second X-37B is already under construction.