GPS Launch Reports Well Received After Delays, Workthroughs

EL SEGUNDO, Calif. (10/18/99) -- The third Navstar Global Positioning System (GPS) Block IIR satellite -- the last in the Block II inventory -- was launched aboard a Delta II from Cape Canaveral Air Station Oct. 7 and was reported functioning well.

This news was well received by personnel from The Aerospace Corporation who worked though a series of delays that began in May.

The launch occurred after a series of weather delays, including delays caused by Hurricane Floyd and thunderstorms, to replace a satellite that had been in operation since 1990.

Replacement Launch

This was the first GPS replacement launch since November 1997. Launch plans were scrubbed this May when a satellite on the pad was damaged by rain that had leaked into the clean room through a hole caused by a sheared screw.

"This satellite, number 46, is replacing number 15," said Don Lapedes, associate director, Block IIA/IIR Satellites, GPS Directorate, The Aerospace Corporation.

"Number 15 is still functioning, but age can affect its reaction wheels in the attitude control system, affecting its orientation."

Before the launch all hardware, software and procedures were reviewed by personnel from The Aerospace Corporation's Medium Launch Vehicles (MLV) Directorate, led by Dr. Robert Fillers, principal director.

MLV's David Zelisse, project engineer, and John Brekke, propulsion manager, worked to verify reliability of the Delta's graphite epoxy motor case after a Titan Solid Rocket Motor Upgrade case segment failed during hydrotest the day before.

The anomaly resolution followed several days of effort by MLV's Jay Bernard and Anna Tai, project engineers, and Jorge Encalada, avionics director, who investigated a Delta II electronics package failure during bench testing the Sunday before launch. The software processes were reviewed and enhanced by MLV's Larry Robinson, project engineer.

Eastern Range personnel, led by Mike Spence, principal director, provided critical launch support in light of the fact that the Delta II had been erected twice. During fairing assembly a nut plate was sheared off, which required last-minute inspection and repair of the spacecraft's solar array.

The fairing work was tracked by Dr. Paul Brennan, MLV senior project lead, Mechanical/ Structures, and Ken Winters, engineering specialist, Structures Department, Engineering and Technology Group. Butch Gardner, manager, Delta Systems, and Ron Tom, director, MLV Systems Directorate, played crucial roles in providing assurance that the vehicle was ready for launch.

The GPS system provides precise navigational information with a constellation of 24 primary satellites orbiting about 11,000 miles above Earth.