Air Force Hopes for November, December Launches of Final GPS IIR-Ms

July 31, 2008

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UPDATED SEPTEMBER 10 2008: With replacement parts currently being manufactured for faulty components that have delayed launch plans, Air Force GPS program managers hope to get the final two modernized Block IIR satellites on orbit by the end of the year.

A tentative launch date of November 7 has been targeted for the Block IIR-20(M), which will carry a payload that includes an experimental L5 signal. If all goes well, the final IIR launch would take place by December 31.

The component in question is the 40-second timer that triggers separation of the third stage booster from the GPS space vehicle. Pre-launch inspections of the spacecraft at Cape Canaveral discovered the problem. If the replacement timers arrive as expected by late September, the IIR-20(M) launch should proceed under the new schedule.

In the meantime, with the GPS satellite constellation currently well above the level needed for full operational capability (FOC), the launch delay has not affected the availability of GPS positioning, navigation, and timing. Some 31 operational GPS space vehicles (SVs) are currently on orbit with only 24 SVs needed to provide an FOC complement for global coverage.