The flight of this X-37B spaceplane is a top-secret military mission so its exact landing time is unknown, having not been released by the U.S. military.
However, when the spaceplane does come down, it is expected to land on a 4.8-kilometer (3-mile) runway at Vandenberg Air Force Base in California.
Developed by NASA, the Boeing Company, and the Defense Advanced Research Projects Agency (DARPA), the X37B program is now operated by the Air Force's Rapid Capabilities Office.
The X-37B was launched into orbit on March 5, 2011, by a United Launch Alliance (ULA) Atlas 5 rocket from Florida's Cape Canaveral Air Force Station.
It was the second launch for the Air Force's Orbital Test Vehicle (OTV) program. So far two spaceplanes have been launched into space. Both are able to be refurbished for repeat visits to low-Earth orbit.
Watch the YouTube video "USAF's second X-37B OTV spaceplane launch" below.
As described by YouTube: "A United Launch Alliance Atlas V rocket successfully launched the second Orbital Test Vehicle (OTV-2) for the Air Force's Rapid Capabilities Office (AFRCO) at 5:46 p.m. EST today from Space Launch Complex-41. The OTV, also known as the X-37B, supports space experimentation, risk reduction, and concept of operations development for long duration and reusable space vehicle technologies."
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