The secretive mission of the U.S. Air Force X-37B space plane has winged past 670 days of flight – just 48 days shy from setting a long duration record for the program.
This Orbital Test Vehicle 5 mission (OTV-5) rocketed into Earth orbit on Sept. 7, 2017 atop a SpaceX Falcon 9 booster from Launch Complex 39A at NASA’s Kennedy Space Center in Florida.
Exactly when the OTV-5 space plane will land is unknown.
Related: The X-37B Space Plane: 6 Surprising Facts
Long duration record?
The last Air Force's X-37B mission, OTV-4 — after 718 days of flight — touched down at NASA’s Kennedy Space Center Shuttle Landing Facility May 7, 2017 — a first for the program. All prior missions had ended with a tarmac touchdown at Vandenberg Air Force Base in California.
Prior to launch of OTV-5, Randy Walden, the director of the Air Force Rapid Capabilities Office said there were many firsts on this mission, making it a milestone for the program. "It is our goal to continue advancing the X-37B OTV so it can more fully support the growing space community," he said.
Related: US Air Force's Secretive X-37B Space Plane (Infographic)
The Air Force also noted that the fifth OTV mission was launched into, and will be landed from, a higher inclination orbit than prior missions to further expand the X-37B's orbital envelope.
Meanwhile, Canadian skywatcher Kevin Fetter of Brockville, Ontario, caught the space plane in this video clip:
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Leonard David is author of the recently released book, "Moon Rush: The New Space Race" published by National Geographic in May 2019. A longtime writer for Space.com, David has been reporting on the space industry for more than five decades. Follow us on Twitter @Spacedotcom or Facebook.