The US air force’s X-37B robotic space plane launched on 20 May from Cape Canaveral Air Force Station, Florida, adjacent to Nasa’s Kennedy Space Centre. This will be the spacecraft’s fourth unmanned mission. As before, most details are classified.
Unclassified tests include a new “ion engine” and the exposure of various materials to see how they degrade in space.
With a wingspan just shy of 15 feet, the X-37B is a quarter the size of Nasa’s now retired space shuttle. It has a payload bay with the capacity of an American pick-up truck and deploys a solar panel to provide power when in space.
The programme began in 1999, under the auspices of Nasa, as a means of conducting experiments in space before bringing them back to Earth for analysis. It was transferred to the US Department of Defense in 2004 and has been the subject of rumours about its true purpose ever since.
Some suggest it is a sophisticated surveillance craft that flies about taking close-up looks at “enemy” satellites. More likely is that it tests equipment that could be used in spy satellites.
The X-37B first flew in orbit during 2010. Since then it has clocked up 1,368 days in space. This is more than the 1,334 days the space shuttle achieved in 30 years and 135 flights.
The plane spent almost two years in orbit on its third mission alone, from 11 December 2012 to 17 October 2014, before landing at Vandenberg air force base, California. The US air force has not said when the X-37B will return to Earth this time.
Twitter: @DrStuClark
