The X-37B, the US Space Force's secretive space plane, will soon take flight again. On Monday, the Space Force announced that it will fly the small, Space Shuttle-shaped vehicle on the program's eighth mission next month. The launch of the vehicle, on a Falcon 9 rocket, is scheduled to occur no earlier than August 21 from Kennedy Space Center in Florida. There are two active X-37Bs in the Space Force fleet, both built by Boeing. The first made its debut flight in April 2010. Since then, the two uncrewed spacecraft have made a succession of longer flights. The first made its longest and latest flight from 2020 to 2022 over a span of 908 days. The second flew more recently, landing at Vandenberg Space Force Base on March 7 after 434 days in orbit. It's likely that the first of these two vehicles, both of which are about 29 feet (9 meters) long and roughly one-quarter the length of one of NASA's Space Shuttle orbiters, will launch next month. Some details about the upcoming flight Over the past decade and a half, the Space Force has largely remained silent about the purpose of this space plane, flying classified payloads and providing only limited information about the purpose of each flight. However, for this flight, OTV-8, the military has provided a bit more detail about its intentions. The vehicle will fly with a service module that will expand its capacity for experiments, allowing the space plane to host payload for the Air Force Research Laboratory and the Defense Innovation Unit.