US Space Force, US Air Force In a testing procedure, the X-37B Orbital Test Vehicle taxis on the flightline March 30, 2010, at the Astrotech facility in Titusville, FLa. (Courtesy photo)

US Space Force, US Air Force The X-37B Orbital Test Vehicle (OTV), the Air Force's unmanned, reusable space plane, landed at Vandenberg Air Force Base at 5:48 a.m. (PDT) June 16. OTV-2, which launched from Cape Canaveral Air Force Station, Fla., March 5, 2011, conducted on-orbit experiments for 469 days during its mission. The X-37B is the newest and most advanced re-entry spacecraft. Managed by the Air Force Rapid Capabilities Office, the X-37B program performs risk reduction, experimentation and concept of operations development for reusable space vehicle technologies. (photo credit: Boeing)

US Space Force, US Air Force The U.S. Air Force X-37B Orbital Test Vehicle 4 landed at NASA's Kennedy Space Center Shuttle Landing Facility in Florida 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. (U.S. Air Force courtesy photo)

US Space Force, US Air Force The U.S. Air Force's X-37B Orbital Test Vehicle 4 is seen after at NASA 's Kennedy Space Center Shuttle Landing Facility in Florida May 7, 2017. Managed by the Air Force Rapid Capabilities Office, the X-37B program is the newest and most advanced re-entry spacecraft designed to perform risk reduction, experimentation and concept of operations development for reusable space vehicle technologies. (U.S. Air Force courtesy photo)

US Space Force, US Air Force The Air Force’s X-37B Orbital Test Vehicle Mission 5 successfully landed at NASA’s Kennedy Space Center Shuttle Landing Facility Oct. 27, 2019. The X-37B OTV is an experimental test program to demonstrate technologies for a reliable, reusable, unmanned space test platform for the U.S. Air Force.