Ongoing problems with the Minotaur 4 rocket will delay by 14 months the launch of the U.S. Air Force’s Space Based Space Surveillance (SBSS) satellite, government documents show.

The Air Force Space and Missile Systems Center planned to launch SBSS in October 2009 with what would have been the first launch of the new Minotaur 4 rocket, built by Orbital Sciences Corp. of Dulles, Va. The service announced that month the launch would be indefinitely delayed with technical problems, though no further explanation was given.

The Minotaur 4 relies on retired U.S. Peacekeeper missile motors for its first three stages and a commercial fourth stage. The rocket’s problem lies with the gas generator on the third stage motor, according to an industry source. The generator continues to run after the third stage motor shuts off, creating residual thrust that is a problem for a rocket designed to put a satellite into a very precise orbit, the source said. Air Force spokeswoman LaGina Jackson was unable to respond to questions by press time.

The SBSS spacecraft, built by Boeing Space and Intelligence Systems of Seal Beach, Calif., is intended to keep tabs on objects in space, particularly in geosynchronous orbit 36,000 kilometers above the equator — the operating location of most communications satellites. SBSS has encountered numerous delays due to technical issues during its development, and the program was restructured in 2007.

As a result of the delay, the Air Force plans to issue a new contract to store the satellite and prepare it for launch when the rocket problems are resolved, according to a Dec. 22 posting on the Federal Business Opportunities Web site. The estimated launch date for SBSS is now December 2010, the posting said.