At 6:43 am US eastern time today, the Air Force’s mysterious X-37B space plane broke a new spaceflight record, surpassing the 717 days, 20 hours and 42 minutes its predecessor spent in orbit just a couple years prior. 

The X-37B, explained: The Air Force is notoriously tightlipped about the X-37B program. The space plane itself, built by Boeing, is 29 feet long and 9.6 feet tall, boasting a wingspan of nearly 15 feet. It's launched vertically aboard a rocket and lands horizontally on a runway. The current X-37B mission is the fifth of its kind (Orbital Test Vehicle 5 - OTV-5) and was launched in September 2017 by a SpaceX Falcon 9 rocket. 

Strange Origins: More than 20 years ago, NASA started looking into developing a cheaper form of the reusable space shuttle that could take crew and cargo into orbit—or potentially ferry people across the globe in suborbital flights lasting just a matter of hours. After changing hands from NASA to the military, the X-37B was born as an uncrewed spaceplane capable of spending months or years in orbit. The first mission was launched in 2010. 

Spy Applications: The Air Force claims the X-37B program will advance reusable spacecraft technologies and that it runs experiments related to avionics, propulsion, and materials testing. The Secure World Foundation, a space policy nonprofit, ran down the possible scenarios in 2017 and thinks the X-37B is very likely a platform to test out future reconnaissance technologies, especially ones that could “disappear” unpredictably or be placed clandestinely in lower orbits. The report casts doubt on the idea that the X-37B is a weapons platform of some kind—it’s just too expensive and impractical.