Task Force

On

The Future of the Global Positioning System(extract)

DSB Task Force on the Future of the Global Positioning SystemDSB Task Force on the Future of the Global Positioning System

National PNT Objectives*National PNT Objectives*• Provide uninterrupted availability of positioning, navigation, and

timing services

• Meet growing national, homeland, economic security, and civil requirements, and scientific and commercial demands

• Remain the pre-eminent military space-based positioning, navigation, and timing service

• Continue to provide civil services that exceed or are competitive with foreign civil space-based positioning, navigation, and timing services and augmentation systems

• Remain essential components of internationally accepted positioning, navigation, and timing services

• Promote U.S. technological leadership in applications involving space-based positioning, navigation, and timing services

* Source: U.S. Space-based Positioning, Navigation, and Timing Policy, NSPD Signed by President Bush, 15 December 2004

DSB Task Force on the Future of the Global Positioning SystemDSB Task Force on the Future of the Global Positioning System

Salient Points from Task ForceSalient Points from Task Force

• The service provided to users is crucial—not sub-optimizing the satellite component

• GPS is a system-of-systems. Satellites, operational control segment & receivers must be effectively integrated

• Minimum constellation size should be 30 satellites—to better support ground forces in varied terrain

• Ambitious requirements are driving the cost of GPS III– Cost & weight must be controlled– Dual launch essential

• Relax emphasis on anti-spoof. Increase attention to anti-jam• Time & attention must be given to maintain GPS as world’s premier

satellite navigation.• Governance needs adjustment & improvement—open-minded

approach is necessary in considering options

DSB Task Force on the Future of the Global Positioning SystemDSB Task Force on the Future of the Global Positioning System

Mask Angle EffectsMask Angle Effects

DSB Task Force on the Future of the Global Positioning SystemDSB Task Force on the Future of the Global Positioning System

5o

15o

X X15o

5o

Accuracy Levels (m)Elevation Mask 50% 95% 99%

24 SV Constellation 5% 1.9 2.8 3.515% 2.3 13.3 >70

30 SV Constellation 5% 1.6 2.2 2.615% 1.9 3.9 8.0

(30-1)

(24-1)

(24-2)

(24-3)

(24-5)

(24-4)

(24-6)

Assumes 1 m User Range Error

Differences caused by Geometric Dilution of Precision effects (DOP x URE = Accuracy)

GPS III Launch CostsGPS III Launch Costs

Single Manifest Dual Manifest Single Manifest Dual Manifest

GPS III SV Cost 125M 250M 125M 250MMid-Size EELV Cost 75M (Buy #1) 90M (Buy #1) 150M (Buy #3) 180M (Buy #3)Launch Cost 200M 340M 275M 430M

On-Orbit Cost/SV 200M 170M 275M 215MFailure Rate 8M 8.5M 11M 11M

Replacement Cost/Slot 208M 178.5M 286M 226M

Delta Cost/Slot +29.5M +60M

EELV Costs: EELV-L=$75M; EELV-M=$90M; EELV-H=$150M (Buy #1) EELV-L=$150M; EELV-M=$180M; EELV-H=$300M (Buy #3 – in Source

Selection)

Failure Rates: 4% Single; 5% Dual (Source: GPS JPO Study, 20 Jul 05)

DSB Task Force on the Future of the Global Positioning SystemDSB Task Force on the Future of the Global Positioning System