First GPS III space vehicle prepares for testing in simulated harsh space environments. Using a 10-ton crane, Lockheed Martin engineers and technicians gently lowered the system module of the U.S. Air Force’s first next generation GPS III satellite into place over its propulsion core, successfully integrating the two into one space vehicle.
GPS III space vehicle one (SV 01) is the first of a new, advanced GPS satellite design block for the U.S. Air Force. GPS III will deliver three times better accuracy, provide up to eight times improved anti-jamming capabilities and extend spacecraft life to 15 years, 25 percent longer than the satellites launching today. GPS III’s new L1C civil signal also will make it the first GPS satellite interoperable with other international global navigation satellite systems.
The systems integration event brought together several major fully functional satellite components. The system module includes the navigation payload, which performs the primary positioning, navigation and timing mission. The functional bus contains sophisticated electronics that manage all satellite operations. The propulsion core allows the satellite to maneuver for operations on orbit.
«The final integration of the first GPS III satellite is a major milestone for the GPS III program», said Mark Stewart, vice president of Lockheed Martin’s Navigation Systems mission area. «This summer, SV 01 will begin Thermal Vacuum testing, where it will be subjected to simulated harsh space environments. Successful completion of this testing is critical as it will help validate our design and manufacturing processes for all follow-on GPS III satellites».
Lockheed Martin is currently under contract to build eight GPS III satellites at its GPS III Processing Facility near Denver, a factory specifically designed to streamline satellite production.
The GPS III team is led by the Global Positioning Systems Directorate at the U.S. Air Force Space and Missile Systems Center. Air Force Space Command’s 2nd Space Operations Squadron (2SOPS), based at Schriever Air Force Base, Colorado, manages and operates the GPS constellation for both civil and military users.
GPS III Facts
| GPS III Specification | |
| Customer | U.S. Air Force Space and Missile Systems Center |
| Mission | Highly accurate 3-D position, velocity and precise time |
| Orbit | Six orbit planes at 55° inclination |
| Altitude | 10,898 NM/20,183.1 km |
| Design life | 15 years; 13-year MMD (Mean Mission Duration) |
| Launch weight | 8,553 lbs/3,879.58kg |
| On-orbit weight | 5,003 lbs/2,269.32 kg |
| Size (W×D×H) | 97×70×134 inch/2.46×1.78×3.40 m |
| Position accuracy | Under one meter, with daily updates from the control segment |
| Electrical Power System | |
| Solar array | 307 feet2/28.52 m2; high-efficiency UTJ (Ultra Triple Junction) cells; 4,480-W EOL (End-Of-Life) capability |
| Battery system | Nickel hydrogen (NiH2); rechargeable |
| Electronics | Central controller with redundant discharge converters, battery chargers |
| Attitude Determination and Control | |
| Design approach | Zero momentum, 3-axis stabilized, Earth-oriented, Sun-Nadir pointing |
| Attitude reference | Static Earth sensor, Sun sensor, control reaction wheels/magnetic torquers |
| Propulsion Subsystem | |
| Design approach | Bipropellant; Hydrazine, NTO (Nitrogen Tetroxide Oxidizer) |
| Propellant capacity | 5,180 lbm |
| Thrusters | 100-lb Liquid Apogee Engine, twelve 0.2-lb REAs, six 5-lb REAs (Rocket Engine Assembly) |
| Structural and Thermal | |
| Modular design | Four aluminum honeycomb panels mounted to a central composite core |
| Passive thermal | Heat pipes in equipment panels, control blankets, thermal coatings, radiators and electrically controlled heaters |
| Navigation Payload | |
| Timekeeping | Enhanced performance for increased subsystem accuracy; improved anomaly resolution; includes multiple atomic frequency standards (Rubidium clocks), radiation-hardened design, high stability timing, automated integrity monitoring |
| Mission data unit | Rad-Hard processor; expanded waveform generation, full message encoding and processing; real-time Kalman filter |
| Crosslink transponder | Legacy UHF (Ultra High Frequency) receive and transmit, precision intersatellite ranging, full-frame modulation and mode control |
| New GPS III signal | L1C (p, d); programmable waveform generation |
| Tracking, Telemetry and Command | |
| Space vehicle computer | Rad-Hard processor; command and telemetry processing, Bus functions, payload accommodation |
| Autonomy | Redundancy management for on-board power and Bus components |
| Security architecture | Encrypted data links using redundant architecture cryptographic units, centralized command decoding, flexible telemetry communications |
| RF links | S-Band, SGLS/USB Transponder |
GPS provides critical situational awareness and precision weapon guidance for the military and supports a wide range of civil, scientific and commercial functions – from air traffic control to navigation systems in cars, cell phones and wristwatches