WASHINGTON A military communications satellite stranded in the wrong orbit April 30 was doomed by an operators wrong computer code, a report released today says. U.S. Air Force Space Command said that the malfunction of a Centaur rocket upper stage that deposited the Milstar satellite into a useless Earth orbit was the result of "a human error made during manual entry of data values into the Centaurs flight software file" prior to the launch. The Air Force said that testing, quality control and check-out by the operator of the Titan IVB rocket, Lockheed Martin Astronautics of Denver, Colorado, failed to detect the error.

The result was the rocket stage lost its attitude control following separation from the main body of the Titan shortly after lift-off. The stages thrusters began firing in a desperate but vain attempt to regain stability, accident investigators said. As a result, the rocket fuel for the thrusters was depleted, leaving the craft out of control and orbiting in the wrong location. By the time the Milstar satellite separated from the Centaur stage, it was too far off course for the satellites own thruster rockets to move it to its proper location. The Air Force subsequently declared May 4 that the satellite was a total loss to the military. Thursday the Air Force Space and Missile Systems Center, Los Angles Air Force Base, California and Lockheed Martin in Denver said they would jointly work on procedures to avoid a similar mishap in the future. The Titan IVB/Centaur rocket was launched from Cape Canaveral, Florida. Milstar satellites are used for secure communications between U.S. military commanders and their field units around the world.