October 05, 2012
Credit: Credit: Boeing
The third Global Positioning System IIF satellite was boosted into orbit Oct. 4, becoming the 32nd GPS satellite in the Pentagon’s constellation.
The GPS IIF series incorporates a new L5 civil signal used for safety operations and search-and-rescue, provides twice the signal accuracy over heritage satellites and carries an on-orbit reprogrammable signal processor. Boeing built the satellite for a 12-year design life, and it is slated to be turned over to the U.S. Air Force for testing in November after initial on-orbit checkout, says Paul Rossnock, vice president of government space systems for Boeing.
The launch took place at 8:10 a.m. (EDT) on a United Launch Alliance Delta IV (4,2 configuration) rocket from Cape Canaveral. The rocket boosted the satellite into orbit 11,000 mi. over Earth.
Operators observed a data anomaly from the Delta IV RL-10B2 upper stage, according to Jessica Rye, United Launch Alliance spokeswoman. The satellite reached its proper orbit and signal acquisition was successful. But officials will analyze the anomaly to determine what happened, if a fix is needed and whether that could affect other launches.
The spacecraft includes a fix to the xenon bulb in the cesium clock designed to address a problem found on the second IIF satellite operating in orbit. “The issue that arose with the IIF-2 cesium clock involved trapped air that, when combined with vacuum and high power, caused an event that resulted in a pump failure,” according to Paula Shawa, a Boeing spokeswoman. “This pump failure necessitated higher-than-desired clock maintenance from the ground crew, so it was decided instead to switch to a rubidium clock.” The zenon bulb sets the frequency standard for the clock, Russnock says.
“A manufacturing change was made to the remaining units and installed on vehicles to mitigate any on-orbit risk,” Shawa says. The fix is to put a higher pressure bulb onto future satellites, Russnock says.
The Pentagon is purchasing 12 GPS IIF satellites. Those after IIF-3 are being purchased through fixed-price contracts. The Government Accountability Office estimates that the GPS IIF program costs about $2.6 billion, significantly more than the originally estimated price. Boeing has crafted a “pulse production” line at its El Segundo, Calif., facility to manufacture the satellites more efficiently. “With the pulse line, we have dramatically improved performance in the ability to get these things built,” Russnock says. When asked if the GPS IIF program is profitable after its challenges, he said it is “stable.”