The second Boeing X-37B landed at Vandenberg AFB, California, on 16 June, after 469 days in orbit, says the US Air Force.
While its mission remains classified, USAF officials have publically praised the spacecraft's performance in orbit. The spacecraft itself is considered experimental, hence the X-designation.
The craft has a payload bay carrying classified equipment for testing.
"The X-37B's advanced thermal protection and solar power systems, and environmental modeling and range safety technologies are just some of the technologies being tested," says Lt. Col. Tom McIntyre, USAF X-37 programme manager.
There are two X-37B airframes in existence. The first airframe, which launched in April, 2010 and recovered that December, is being refurbished for a scheduled October launch.
USAF did not immediately respond to questions.