US Air Force X-37B reusable space vehicle prototype to launch at year-end

The US Air Force's X-37B, a prototype space plane designed to ferry small payloads to and from Earth orbit, will launch onboard an Atlas 5 rocket in November or December of this year. This changes the launch schedule for the craft, which was previously slated for February 2009.

The X-37B is also called the Orbital Test Vehicle and the launch will now take place from Cape Canaveral onboard a 501 version of the Atlas 5 rocket. This configuration features a five-meter payload fairing enclosing the spacecraft and the Centaur upper stage.

In size the X-37B is about one-quarter the length and width of a space shuttle orbiter. It is about 27 feet long and has a 15-foot wingspan. According to the USAF, the Boeing-manufactured space plane will weigh about five tons at launch. The X-37B is scheduled to make an automated re-entry and land on a conventional runway at Edwards Air Force Base, California.

According to the Air Force, the objective of the flight will be "risk reduction, experimentation, and operational concept development for reusable space vehicle technologies."

The X-37 had started as a programme under NASA in 1999, but moved under the Defense Advanced Research Projects Agency (DARPA). Drop tests of the X-37 were performed for DARPA using Scaled Composites' White Knight high altitude plane here.

White Knight is better known for her role in lifting SpaceShipOne on her X Prize-winning commercial space flights in 2004. (See: White Knight Two, mothership for Virgin Galactic's spaceliner programme, rolls out)