NASA’s shuttles used fuel cells, but the X-37B is powered by a deployable solar array. This was supposed to give the craft a nine-month mission length, instead of the 2.5 weeks NASA’s shuttles had. The Air Force has decided to test the craft beyond this timeline. But the X-37B’s mission is secret, the contents of its unpressurized payload is secret, and the new landing date is undetermined. Curiouser and curiouser.