Launch Delay

Block IIF Launch Delayed until ThursdayMay 25, 2010
After four delays, GPS spacecraft IIF-1 is set to be launched this Thursday, May 27, from Cape Canaveral Air Force Station in Florida.

The countdown to launch of GPS IIF-1 was halted Monday night at about T-6 seconds. Computers detected a possible problem with the steering system on one of the twin solid rocket boosters.
"The launch attempt of Delta IV GPS IIF SV-1 was scrubbed Monday night, May 24," reads an Air Force announcement.

"During the final seconds of the launch countdown, an anomalous data signature with the thrust vector control system on one of the two solid rocket motors (SRMs) mounted to the Delta IV booster was detected. The thrust vector control system is used to steer the SRMs during flight. The data signature triggered an automatic abort in the launch countdown scrubbing Monday's launch attempt. Mission managers are studying the situation to determine a corrective action plan.

"The Delta IV rocket and GPS IIF SV-1 satellite are safe and secure at this time. The next launch attempt has been tentatively set for Thursday. The launch window for Thursday is 11-11:19 p.m. EDT."

The new IIFs will broadcast the operational civil L5 signal, intended for safety-of-life applications. It will be compatible with Galileo, GLONASS, and QZSS, with the goal to be interoperable as well. L5 will transmit at a higher power than current civil GPS signals, with wider bandwidth and lower frequency that may enhance indoor reception.

The first launch attempt May 20 was scrubbed when mission managers determined a piece of ground support equipment used to control one of the swing arms on the Fixed Umbilical Tower was not operating correctly and needed replacing, and launch was delayed 24 hours. Then a telemetry signal issue caused a second scrub during the countdown, and launch was to be Sunday, then was extended to Monday before this fourth delay.