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Space


GPS Block II F

The GPS Space Segment consists of the GPS satellite constellation with its associated ground equipment, flight support equipment, computer programs, and SV to Launch Vehicle (LV) interface equipment. The Space Segment provides the following capabilities in support of the GPS mission: L-Band Signal-In-Space (SIS) capability, a UHF signal for crosslink transmission, and a S-Band uplink/downlink interface to the control segment. The operational constellation includes Blocks II, IIA, IIR, IIR-M and IIF satellite constellations.

The IIF Space Segment has responsibility for the space-based portions of the Navigation and NDS missions, for the crosslink operations, and for GPS IIF Autonav performance. Individual satellites are equipped with government furnished payloads and associated downlinks to support the NDS mission. The Block IIF System is interoperable with the NDS, existing Block IIA/IIR/IIR-M satellites, the Control Segment (CS) (including planned upgrades), and the user equipment segment. GFE and facilities will be provided for the Control Segment.

The Block IIF satellite, the latest generation of GPS vehicles, are managed by the NAVSTAR GPS Joint Program Office. Boeing North American Space Systems Division is the prime contractor for the Block IIF, which incorporates current technology to sustain the GPS utility for military and commercial use.

The Block IIF satellites are functionally equivalent to the IIR/IIR-M satellites and pave the way towards operational M-code after IOT&E in 2010. Block IIF also adds a new separate signal for civilian use, designated L5. This variant will also have increased, adjustable signal power.

The NAVSTAR Global Positioning System (GPS) Joint Program Office procurement of the NAVSTAR Global Positioning System Sustainment (Block IIF) will sustain the quality GPS signal as a worldwide utility well into the next century at the lowest technical risk and acquisition and life-cycle costs. Under a single contract, the system level prime contractor is responsible for consolidating the satellite and operational control subsystems into one optimized package, and integrating this package with a government furnished launch vehicle, secondary payload(s), and the Air Force Satellite Control Network. GPS Block IIF does not include the acquisition or production of any user equipment. The contractor will deliver this Block IIF System to the Government, and Air Force Space Command will launch and operate the system on a daily basis. The system will be backward compatible with previous GPS satellite, control facilities, and user equipment.

The Block IIF system allows affordable technology insertion and block upgrades, while emphasizing compatibility and interoperability with the current space vehicles, ground control system, and user equipment. The system will interface with the new GPS Operational Control System (OCS) architecture currently under development, and with the Air Force Satellite Control Network (AFSCN).

Air Force will use the Evolved Expendable Launch Vehicle (EELV) as the booster.

The requirement to maintain a worldwide navigation service provided by a 24 satellite constellation for military and civilian users drives the Block IIF program.

The Block IIF spacecraft will feature advanced atomic clocks to greatly improve performance and give the control segment greater visibility into the health of the units. With four frequency standards composed of both cesium and rubidium technologies, these extremely accurate GPS atomic clocks must keep time to within 8 nanoseconds a day.

The improvement involves converting the GPS cesium clocks from analog to digital - the first ever use of the commercially available digital cesium standard technology on spacecraft - and are a result of long-standing development work on frequency standard technologies by the U.S. Naval Research Laboratory in Washington, DC.

The processor-controlled cesium clocks continuously optimize their performance by adjusting internal parameters and compensating for environmental effects. They will also perform self-checkout diagnostics.

The current analog clocks are optimized during manufacturing. As components age, the clock performance becomes less predictable and the output frequency of the clocks varies with changes in temperature or the magnetic field. The digital cesium standard represents the next step in the evolution of frequency standards in space and promises to result in better accuracy for military and civilian GPS users alike.

The market for atomic clocks is shrinking as GPS replaces atomic clocks in a number of their former applications. To preserve the industrial base and advance clock technology, the JPO, through NRL, funds development of new clock technologies.

The proposed procurement for a constellation of 51 GPS Block 2F series satellites was later reduced to 33 satellites.

As of 2005 the US Air Force intended to purchase non recurring engineering for production of satellites with options to purchase up to 15, Global Positioning Systems (GPS) Space Vehicles (SV) with identical capabilities of the IIF satellite, and associated services and Long Lead-time Items. The Air Force will only procure enough additional IIF-like SVs to sustain the GPS constellation until the first GPS III SV with new capabilities can provide for constellation sustainment. The anticipated first SV delivery is November 2010 to support a launch date of April 2011, with delivery of subsequent SVs nominally every four months thereafter. The Government has been contracting with The Boeing Company, 5301 Bolsa Avenue, Huntington Beach, CA 92647 for the development and production of 12 GPS IIF SVs.

Significant cost increases and schedule delays occurred in 2006. The program requested an additional $151 million to cover testing and production costs, did not award the contractor $21.4 million in award fees, and incurred an estimated 17-month delay in the launch of the first IIF satellite. According to the program office, the Block IIF technologies are mature.

The program office had relied on earned value management reports to monitor the contractor's production efforts, but discovered in 2006 that the contractor's earned value management reporting system was not accurately reporting cost and schedule performance data. According to program officials, they have addressed these reporting deficiencies and have requested separate audits to identify the root causes of the problems. In addition, the program office has increased its personnel at the contractor's facility to observe operations and to verify that corrective measures are being taken to address deficiencies.

The program office estimates that the planned launch of the first IIF satellite will be delayed 17 months from January 2007 to May 2008 due to schedule and testing delays. During 2006 the contractor encountered a series of delays with the delivery of hardware components from subcontractors as well as the development of the software that runs equipment used to test payload and bus components. The concurrent development and production of the first three IIF satellites has led to significant cost increases and schedule delays. As a result, the program office has requested approximately $151 million in funds to be reprogrammed this year. This amount is based on the contractor's cost estimate to complete development and production of the first three satellites.

In June 2006 the program reported that 40 modernized GPS satellites (a combination of IIR, IIR-M and IIF satellites) would be procured. However, by early 2007 the program office planned to procure 7 fewer satellites-meaning 12 IIF satellites are to be procured instead of 19. In order to sustain the GPS constellation, 12 IIF satellites are needed until the first GPS III satellite is launched in fiscal year 2013. If approved, the reduced number of IIF satellites and a possible increase in program funding will increase unit cost per satellite, potentially breaching Nunn-McCurdy thresholds.

The program office did not award the contractor $21.4 million in 2006 available award fees due to cost overruns and schedule delays. According to program officials, the $21.4 million will be used to cover a portion of the cost overruns. The procurement of the IIF satellites and control system used a contracting approach that gave the contractor full responsibility for the life cycle of the program and allowed parallel development and production efforts which resulted in cost overruns and schedule delays.




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