The mysterious space plane of the U.S. Air Force has finally landed in California after going on a top-secret mission in space for nearly two years, said military officials. Also known as the Orbital Test Vehicle or X-37B, the space plane resembles a miniature space shuttle of NASA.

 Similar to the space shuttle, the X-37B also lands on runways, but it can do so without pilots controlling it, according to ABC News.

Built by Boeing, the current space plane reportedly makes use of solar panels to power its orbit in space.

The space plane measures 29 feet, with a 15-foot wingspan and weight of 11,000lbs.

The unmanned re-usable orbital test vehicle touched down at 9:24 a.m. local time Friday at Vandenberg Air Force Base in California after 674 days in space, according to the Air Force Base's officials.

The BBC reports that photos of the space plane have also been released by the 30th Space Wing show as it touched down at Vandenberg.

The latest flight from which the space plane touched down from was apparently its third mission already. According to the Air Force, the fourth mission of the space plane will take place sometime 2015 from Cape Canaveral in Florida. The first space plane mission occurred in April 2010, which took eight months to finish, while the second launch of the space plane happened in March 2011, with it remaining in space for 15 months.

Meanwhile, the exact nature of all missions of the space plane remains unknown. However, one of the few things known about the space plane's top secret missions is that the aircraft can remain in orbit for long periods of time.

Several experts have suggested that the space plane carries spy gear in its cargo bay, reports the Associated Press. Other theories are more out of this world. Some reportedly sound like a script from a James Bond film, saying that the space plane can capture satellites of other nations and even shadow China's space lab.

With the public contemplating, Air Force officials released a statement to U.S. media and said that the space plane only performs "risk reduction, experimentation and concept-of-operations development for reusable space vehicle technologies", toned down from spy work speculations.

The written release by the Air Force basically announced that the space plane had been conducting "on-orbit experiments."

The X-37B programme began in 1999. It is currently managed by the Air Force's Rapid Capabilities Office.

The reality behind the space plane's missions is that nobody really knows what it does. The only explanation is that it is reportedly testing technologies which could pave the way for future satellite missions.

According to reports, NASA recently gave a work space at the Kennedy Space Center used before for shuttles to the X-37B programme. This means that what the missions the space plane is involved in is a long-term project for the Air Force.

The space plane's real objective may never be known, but they definitely are of high value.

 

 

Below is a video of the OTV-3 landing. The X-37B Orbital Test Vehicle mission 3 (OTV-3), the Air Force's unmanned, reusable space plane, landed at Vandenberg Air Force Base at 9:24 a.m. Oct. 17. Credit: USAF.