The Air Force’s top-secret space plane just celebrated its one-year anniversary of space flight.

As of May 20, the X-37B had been in orbit for one year, the third time the craft has accomplished such a goal.

The space plane launched on its first mission in April 2010, staying in orbit for 224 days. The second and third missions in 2011 and 2012, respectively, both lasted longer than a year.

Now the fourth mission has hit the one-year mark as well, with no announced plans to bring the plane back to Earth anytime soon.