The US Military's X-37B spaceplane is usually referred to as a 'secret' project. It's not really - considering that its return to Earth after a two year mission in orbit was public knowledge and covered widely across the news.
True, what the plane was actually doing in orbit is still something of a secret. But it's likely to be a fairly mundane communications and surveillance test, rather than a search for alien Moon bases.
Fortunately, the non-secret aspects of the secret spaceplane (OTV-3) mean that we also get this incredible video of it actually landing back at Vandenberg Air Force Base. It's an astonishing clip, but remember, the plane is unmanned, so there are definitely no people in there. And no aliens. Probably. Maybe.