Mystery plane returns - A US top secret plane has landed on the coast of California after orbiting the planet for two years. The air force base located at the coast of Southern California was the place where the mystery place returned. What exactly did the secret plane do for two years and what use was orbiting around the earth for two years for?

The Vandenberg Air Force Base at Southern California was where the mystery plane returned. The plane called X-37B appears like a miniature version of a space shuttle. The X-37B had reportedly orbited the earth for two years for "on-orbit experiments."

However, a number of conspiracy theories regarding why the mystery plane returned have gone viral. Specialists claimed the X-37B carried a number of spy gear collected from around the world before being brought to Vandenberg Air Force. Other theories claim the X-37B aircraft had taken note and recorded all satellites in orbit. Another theory claims the X-37B hopes to copy China's space lab.

With regards to why the mystery plane returns after two years of orbit, Air Force officials have stated that the aircraft had done its part of "risk reduction, experimentation and concept-of-operations development for reusable space vehicle technologies." No other statements have been made.

Before the mystery plane returned to Vandenberg Air Force, the aircraft had been passed on from one organization to the next. Right after being in the care of NASA, X-37B is now in the rightful management of Air Force Rapid Capabilities Office.

The X-37B is only one out of two planes by Boeing. X-37B is at 29 feet long and stands at 9 ½ feet tall. The wingspan is just under 15 feet and the aircraft weighs around 11,000 pounds. Even after the mystery plane returns, another orbit is scheduled and the X-37B will be launched by 2015 at Cape Canaveral, Florida.