The X-37B Orbital Test Vehicle is an unmanned space vehicle that will be used by the United States Air Force to explore reusable vehicle technologies in support of long-term space objectives. These objectives include space experimentation, risk reduction, and concept of operations development. Boeing's involvement in the program began in 1999. The X-37B Orbital Test Vehicle was built at several Boeing locations in Southern California, including Huntington Beach, Seal Beach and El Segundo.The X-37B is one of the world's newest and most advanced re-entry spacecraft. Designed to operate in low-earth orbit, 110 to 500 miles above the Earth at a nominal speed of about 17,500 miles per hour, the vehicle is the first since the Space Shuttle with the ability to return experiments to Earth for further inspection and analysis. All avionics on the X-37B are designed to automate all de-orbit and landing functions. Additionally, there are no hydraulics onboard the X-37B; flight controls and brakes use electromechanical actuation.