Mum’s the word: The secretive X-37B space plane has winged its way past the 200 day mark, carrying out a classified agenda for the U.S. Air Force.
Rocketed into orbit aboard a United Launch Alliance Atlas V rocket from Florida’s Cape Canaveral Air Force Station back on May 20 of this year, the reusable robotic space plane is also dubbed OTV-4 (short for Orbital Test Vehicle-4).
OTV-4 is the second flight of the second X-37B vehicle built for the Air Force by Boeing Space & Intelligence Systems.
Only two reusable X-37B vehicles have been confirmed as constituting the fleet.
Mini-shuttle
The X-37B space plane looks like a miniature version of NASA’s now-retired space shuttle orbiter. The military space plane is 29 feet (8.8 meters) long and 9.5 feet (2.9 m) tall, and has a wingspan of nearly 15 feet (4.6 m). The spacecraft sports a payload bay about the size of a pickup truck bed.

Recovery crew members process the X-37B Orbital Test Vehicle at Vandenberg Air Force Base after the program’s third mission complete.
Credit: Boeing
The Air Force Rapid Capabilities Office (AFRCO) runs the X-37B program.
While the overall duties of the space plane remain secretive, it was previously announced that this craft carries a NASA advanced materials investigation and an experimental propulsion system developed by the Air Force.
Track record
- The first OTV mission began April 22, 2010 and concluded on Dec. 3, 2010, after 224 days in orbit.
- The second OTV mission began March 5, 2011, and concluded on June 16, 2012, chalking up a mission of 469 days.
- The X-37B program completed its third mission on October 17, 2014 following 674 days on-orbit after its December 3, 2012 launch. This last flight extended the total number of days spent on-orbit for X-37B craft to 1,367.
Florida landing?
To date, all flights of the X-37B touched down at Vandenberg Air Force Base in California. When and where OTV-4 will return to Earth is not known.

Former shuttle processing area at the Kennedy Space Center has been overhauled by Boeing to prep the military’s secretive X-37B space plane.
Credit: Malcolm Glenn
In 2014, it was announced that Boeing Space & Intelligence Systems had consolidated its space plane operations by making use of NASA’s Kennedy Space Center (KSC) in Florida as a landing site for the X-37B.
According to Boeing, a former KSC space-shuttle facility known as Orbiter Processing Facility (OPF-1) has being converted into a structure that will enable the Air Force “to efficiently land, recover, refurbish and relaunch the X-37B Orbital Test Vehicle (OTV).”