Secret US spacecraft lands in California - Ninemsn

A secret unmanned US Air Force spacecraft has landed at Vandenberg air base in California after a 469-day mission.

The X-37B Orbital Test Vehicle, the military's second unmanned, reusable space plane, conducted experiments in orbit during its mission, the Air Force 30th space wing said in a press release.

An earlier test flight by another X-37B lasted seven months in 2010, on a mission designed to test the viability of reusable drone access to space.

The secretive nature of the project has led to speculation about its role in the military - some say it can be used to spy on communications or to deploy small satellites.

Russia has charged that the US is exploring the weaponisation of space, a notion the Air Force flatly rejects.

Designed along the lines of the retired space shuttle, the current mission was launched in March 2011 with an Atlas V rocket, with the intention of fine-tuning the vehicle and replicating the results of previous tests, officials said last year.

Lieutenant Colonel Tom McIntyre, the programme manager, said Saturday that the X-37B programme brought "singular capability to space technology" now that the space shuttle fleet was retired.

"The return capability allows the Air Force to test new technologies without the same risk commitment faced by other programmes," he said in the statement.

The spacecraft has a wingspan of 4.5 metres, is 8.9 metres long and weighs 4,990 kilograms. Built by Boeing's secretive Phantom Works division, the plane is powered by batteries and solar cells.

The X-37 programme began in 1999 under NASA's guidance before being transferred in 2004 to the Pentagon's Defence Advanced Research Projects Agency (DARPA), before winding up in the hands of the Air Force.

The Air Force plans another launch, before year's end, of the first X-37B that flew in 2010.