Analysis of the GPS Block IIF Space Vehicle Required On-Orbit Life (ROOL)

Andy Wu

Abstract:	The GPS Block IIF is a development and production program to sustain the GPS utility for military and commercial applications. The Block IIF contractor, Boeing North America (BNA), has the total system responsibility for both the Block IIF satellites and supporting grotmd control including planned upgrades. The Block IIF system will be interoperable with the existing GPS Block IW IIR satellite constellations, control segment and user equipment segment. BNA will initially produce 6 “gap filler” space vehicles (SVs) to provide coverage during the transition from the GPS Block IIR to Block IIF. Beyond that the contract has one option for 15 SVs and a second option for 12 additional svs. Implementing DOD acquisition reform, the Air Force has streamlined the Block IIF program by greatly reducing the number of military standards applied and decreasing the number of contract data requirement lists delivered. The Block IIF space vehicle required on-orbit life (ROOL) is designed to ensure that BNA produces quality long life SVs with less government oversight. BNA elected to warrant operation of each of the Block IIF SVs for a period of 12.7 years Under the Block IIF ROOL, if either of the first two SVs fails during their fast four years, BNA must replace that SV. If either of these two SV becomes nonoperational after the four years period but before the warranty period of 12.7 years, BNA would be liable for a prorated negative performance depending on the number of years the SV has been in operation. After the second SV, full replacement of SV would be made within the first year of operation and then the negative performance would be prorated to zero at 12.7 years. On the other hand, a prorated positive performance is earned if the SV exceeds the warranty period of 12.7 years. The negative performance and the positive performance will be accumulated at each SV failure and form a performance pool. At the end of contract, the government will be entitled to a liquidated amount of any net negative performance in the performance pool. However, any net positive performance at the end of contract would not be paid back by the government. In this paper the on-orbit performance incentive provisions for the GPS Block II/HA and the GPS Block IIR SV are provided for comparison. The Block IIF SV ROOL is then described and the average performance per SV is estimated based on the Block IIF SV reliability prediction. The average performance pools for a total of 6 Block IIF SVs and 33 Block IIF SVs are computed as a function of the years after the first successful SV launch and based on the SV reliability prediction and launch schedules. Results using other reliability predictions are also provided to show that the Block IIF SV ROOL is a fair commercial-style warranty.
Published in:	Proceedings of the 53rd Annual Meeting of The Institute of Navigation (1997) June 30 - 2, 1997 Albuquerque, NM
Pages:	177 - 185
Cite this article:	Wu, Andy, "Analysis of the GPS Block IIF Space Vehicle Required On-Orbit Life (ROOL)," Proceedings of the 53rd Annual Meeting of The Institute of Navigation (1997), Albuquerque, NM, June 1997, pp. 177-185.
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