The X-37B is a kind of robotic space plane, built by the US. It’s been in Earth’s orbit for more than 500 days. And its real purpose is a complete mystery.
The X-37 started life way back in 1999 when NASA asked Boeing’s Phantom Works division to develop an orbital test vehicle. This was a civilian project, and the X-37 was originally spec’d as an unmanned, robotic spacecraft that would rendezvous with satellites to refuel, repair them, or crash them back to Earth once their lifecycle was complete. But, in 2004, the project was transferred to DARPA and since then, it has been highly classified.
The amateur skywatching community that documents satellites say it’s orbiting between 43.5 degrees north latitude to 43.5 degrees south latitude. That’s a band around the middle of Earth that takes in much of the US, Middle East, and Asia, but is away from Russia, and Europe. Spotters suggest that at the altitude of 350km, it is ideal altitude for spying, but too low to refuel or fix other satellites.
So the question is, what is X-37B actually doing up in space? The USAF’s official fact sheet says that “The primary objectives of the X-37B are twofold: reusable spacecraft technologies for America’s future in space and operating experiments which can be returned to, and examined, on Earth.” This is probably only partially true (but Boeing is on the books to create the X-37C, which will at least 65% larger and have the ability to carry up to six astronauts). More realistically, X-37B is probably carrying prototype reconnaissance gear, for spying on the Middle East and other sensitive geopolitical regions.