After more than a year in orbit the Air Force’s mysterious mini-space shuttle is set to land at Vandenberg Air Force Base in California sometime this week. Air Force officials say a landing could come as early as Wednesday.

Measuring 29 feet in length and having a 15-foot wingspan, the unmanned re-usable X-37B Orbital Test Vehicle looks like a miniature version of NASA’s now retired space shuttles.

The reusable spacecraft went into orbit on March 5, 2011, but as was the case during its first launch in 2010, very little has been known about its mission or what payloads it might be carrying because its missions are classified. That has led to speculation that the spacecraft is involved in intelligence gathering operations or the testing of new technologies. . .