Mystery space plane launches again.

The US Air Force successfully launched it’s X-37B space plane into orbit this week using an Atlas 5 rocket. The launch had been delayed several times with the Air Force saying “final approvals” were still pending.

The vehicle is around a quarter of the size of the space shuttle, and previous missions have lasted hundreds of days, with the re-useable craft landing on runways each time.

Reports and speculation on the purpose of the X-37B range from “testing advanced spy satellite sensors” to “Earth observation, surveillance or spying, or perhaps deploying a satellite”. A report earlier this year ended rumors that it was being used to spy on a prototype Chinese space module, by pointing out that the two spacecraft were in completely different orbits.