The US Air Force’s secretive X-37B spaceplane landed after 718 days in orbit — just twelve days shy of a full two years. What was it doing up there in the sky? The government won’t say. Even the spaceplane’s budget is a secret. But the X-37B’s landing wasn’t so stealth. The spaceplane caused a sonic boom that woke up people living near NASA’s Kennedy Space Center in Florida.

The secret, reusable spaceplane is made by Boeing and is unmanned, allowing it to conduct extended missions, even if the public has no idea what those missions might be. This was the X-37B’s fourth mission (all secret, of course) and the spaceplane typically lands in California, not Florida. Again, we don’t know enough about the spaceplane’s purpose to speculate about why it landed in Florida and woke up the neighbors this time around.

The X-37B Orbital Test Vehicle (OTV) has now spent an astonishing 2,085 cumulative days in orbit since its first mission in April of 2010. When the spaceplane first took off on its most recent mission on May 20, 2015, David Bowie, Leonard Cohen, and Prince were all still alive, and Donald Trump was still a month out from announcing his bid for president — something that was met with little more than jokes at the time.

“The landing of OTV-4 marks another success for the X-37B program and the nation,” X-37B program manager Lt. Col. Ron Fehlen said in a statement without giving away the plot of this real-life mystery movie we seem to be living in.

The US Air Force's 4th mystery X-37B space plane mission / image by Space.com / source Space.com On May 20, 2015, the U.S. Air Force's fourth classified X-37B space plane mission - called Orbital Test Vehicle 4 - launched into orbit from Space Launch Complex (SLC)-41 at Cape Canaveral Air Force Station, Florida. The mission landed on May 7, 2017 after a record-shattering 718 days in space.

OTV-4 stationary at the Shuttle Landing Facility / image by U.S. Air Force / source Wikipedia.com / license CC0 The Air Force's X-37B Orbital Test Vehicle mission 4 landed at NASA 's Kennedy Space Center Shuttle Landing Facility May 7, 2017. Managed by the Air Force Rapid Capabilities Office, the X-37B program is the newest and most advanced re-entry spacecraft that performs risk reduction, experimentation and concept of operations development for reusable space vehicle technologies.

“The hard work of the X-37B OTV team and the 45th Space Wing successfully demonstrated the flexibility and resolve necessary to continue the nation’s advancement in space,” Randy Walden, the director of the Air Force Rapid Capabilities Office, said in a statement. “The ability to land, refurbish, and launch from the same location further enhances the OTV’s ability to rapidly integrate and qualify new space technologies.”