Block IIF Launch Delayed until Thursday

Block IIF Launch Delayed until Thursday
May 25, 2010

http://www.gpsworld.com/gnss-system/gps-modernization/news/block-iif-launch-delayed-until-thursday-9982?print=1

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.