On November 17, 2006, the U.S. Air Force announced it would develop the X-37B from the NASA X-37A. The Air Force version is designated X-37B Orbital Test Vehicle (OTV). The OTV program builds on industry and government investments by DARPA, NASA and the Air Force. The X-37B effort will be led by the Air Force Rapid Capabilities Office and includes partnerships with NASA and the Air Force Research Laboratory. Boeing is the prime contractor for the OTV program. The X-37B can remain in orbit for up to 270 days at a time. The Secretary of the Air Force states the OTV program will focus on "risk reduction, experimentation, and operational concept development for reusable space vehicle technologies, in support of long term developmental space objectives."
The X-37B was originally scheduled for launch in the payload bay of the Space Shuttle, but following the Columbia accident, it was transferred to a Delta II 7920. It was subsequently transferred to a shrouded configuration on the Atlas V following concerns over the unshrouded spacecraft's aerodynamic properties during launch. The first orbital flight of the first X-37B, named USA-212, was launched on an Atlas V rocket at Cape Canaveral Air Force Station, Florida on April 22, 2010, at 23:58 GMT. The spacecraft was placed into low Earth orbit for testing. While the U.S. Air Force revealed few orbital details after the first X-37B was successfully placed in orbit due to the secretive nature of the mission, amateur astronomers claimed to have identified the experimental spacecraft in orbit and shared their findings. A worldwide network of amateur astronomers reportedly determined, as of May 22, 2010, that it was in an inclination of 39.99 degrees, circling the Earth once every 90 minutes in an orbit 401 by 422 kilometres (249 by 262 mi).
Following their missions, X-37B spacecraft are to land on a runway at Vandenberg Air Force Base, California, with Edwards Air Force Base as an alternate site. A second X-37B is being manufactured for a test mission scheduled for 2011. The China Daily newspaper wrote that the X-37B program raised concerns about an arms race in space. The Xinhua News Agency took a more moderate tone in questioning if the secretive program might lead to weapons in space. The Pentagon has strongly denied claims that the X-37B's mission supports the development of space-based weapons. A group of amateur sky watchers with members around the globe has concluded that the spacecraft's mission is to support space-based surveillance and reconnaissance technology; they reported the X-37B's track took it over North Korea, Afghanistan and other trouble spots. According to them, the spacecraft passes over the same given spot on Earth every four days, and operates at altitude of 255 miles (410 km), which would be typical for a military surveillance satellite.
The X-37B sits on the runway at Vandenberg AFB
The U.S. Air Force announced on November 30, 2010, that the X-37 would return for a landing during the December 3-6 timeframe. As scheduled, the X-37B de-orbited, reentered Earth's atmosphere, and landed at Vandenberg AFB on December 3, 2010, at 1:16 a.m. PST (0916 UTC). Source: Wikipedia