Launch of U.S. Air Force’s Secretive Space Plane Delayed Until Dec. 11

Photo Credit: Alan Walters /

CAPE CANAVERAL, Fla – United Launch Alliance (ULA) has stated that it is working with the Eastern Range to launch one of the U.S. Air Force’s Orbital Test Vehicles (OTV) no earlier than Dec. 11. This marks the fourth delay of the unmanned space plane after an issue arose with the upper stage of a Delta IV launch vehicle.

During the Oct. 4, 2012 launch of a Delta IV Medium rocket with its Global Positioning System (GPS) IIF-3 satellite payload, the upper stage’s RL-10 engine experienced a lower-than-normal engine chamber pressure. This anomaly apparently was deemed to be fairly serious and given that the Atlas V and Delta IV both use a similar version of the RL-10, ULA has opted to review flight data.

“We are working toward a planning date for the launch of OTV of Dec. 11, pending approval from the range,” said ULA’s Jessica Rye.

The Eastern Range is managed by the U.S. Air Force’s 45th Space Wing. This will mark the third flight of one of the U.S. Air Force’s unmanned space shuttles and the first time that one of the space planes has been reused (the orbiter used on the OTV-1 flight will be reused on this upcoming mission).

The RL-10 is a liquid-fueled rocket engine that is manufactured by Pratt & Whitney Rocketdyne. The engine burns cryogenic liquid hydrogen and liquid oxygen. The engine’s development started in the 1950s. The latest version of this engine is what is employed in both the Atlas V and Delta IV families of rockets.

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