The scheduled October 23 launch of GPS IIF-5, the fifth in the current “follow-on” generation of GPS satellites, has been postponed in order to complete a review of an adjustment made to the rocket’s upper stage engine. A fuel leak in that engine of the Delta 4 rocket during a GPS launch in October of last year created some worries for the Air Force and the United Launch Alliance (ULA), although the satellite successfully reached its intended orbit despite the upper stage producing less thrust than expected.
A subsequent investigation determined a fuel leak in the engine system was responsible. Two medium Delta IV rockets and one heavy version have launched since then, but ULA said continued investigation had produced new information about the engine’s first start.
While no new definitive launch date has been set, the ULA released a statement:
“The ongoing Phase II investigation has included extremely detailed characterization and reconstructions of the instrumentation signatures obtained from the October 2012 launch and these have recently resulted in some updated conclusions related to dynamic responses that occurred on the engine system during the first engine start event.
“The GPS IIF-5 Delta IV launch is being delayed to allow the technical team time to further assess these updated conclusions and assess the improvements already implemented and determine whether additional changes are required prior to the next Delta IV launch.
“The Delta IV booster for the GPS IIF-5 mission has completed the standard processing and checkout on the launch pad and will be maintained in a ready state for spacecraft mate and launch pending completion of this assessment. A new launch date will be established when the assessment of the updated dynamic response information is completed in the coming weeks.”