GPS number III

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.

An artist’s rendering of the GPS III satellite
An artist’s rendering of the GPS III satellite

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.

Lockheed Martin recently fully integrated the U.S. Air Force’s first next generation GPS III satellite at the company’s Denver-area satellite manufacturing facility.  The first in a design block of new, more powerful and accurate GPS satellites, GPS III Space Vehicle One is now preparing for system-level testing this summer
Lockheed Martin recently fully integrated the U.S. Air Force’s first next generation GPS III satellite at the company’s Denver-area satellite manufacturing facility. The first in a design block of new, more powerful and accurate GPS satellites, GPS III Space Vehicle One is now preparing for system-level testing this summer

 

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

 

Leave a Reply