Tag Archives: GPS III

GPS III ground control

Once the next-generation GPS III satellites begin launching later this year, a series of updates to the current ground control system from Lockheed Martin will help the U.S. Air Force gain early command and control of the new satellites for testing and operations.

The fourth Lockheed Martin-built GPS Ill satellite is fully integrated
The fourth Lockheed Martin-built GPS Ill satellite is fully integrated

In 2016 and 2017, the Air Force placed Lockheed Martin under two contracts, called GPS III Contingency Operations (COps) and M-Code Early Use (MCEU), which directed the company to upgrade the existing Architecture Evolution Plan (AEP) Operational Control System (OCS), which operates today’s GPS constellation. These upgrades to the AEP OCS are intended to serve as gap fillers prior to the entire GPS constellation’s operational transition to the next generation Operational Control System (OCX) Block 1, now in development.

In April 2018, the Air Force approved Lockheed Martin’s critical design for MCEU, essentially providing a «green light» for the company to proceed with software development and systems engineering to deploy the M-Code upgrade to the legacy AEP OCS. The Air Force gave a similar nod to COps in November 2016. COps is now on schedule for delivery in May 2019 and MCEU is scheduled for delivery in January 2020.

«The Air Force declared the first GPS III satellite ‘Available for Launch’ last year, and it’s expected to launch later this year. Nine more GPS III satellites are following close behind in production flow», explained Johnathon Caldwell, Lockheed Martin’s program manager for Navigation Systems. «GPS III is coming soon, and as these satellites are launched, COps and MCEU will allow the Air Force the opportunity to integrate these satellites into the constellation and to start testing some of GPS III’s advanced capabilities even earlier».

 

MCEU Capabilities:

Part of the Air Force’s overall modernization plan for the GPS, M-Code is an advanced, new signal designed to improve anti-jamming and anti-spoofing, as well as to increase secure access to military GPS signals for U.S. and allied armed forces.

To accelerate M-Code’s deployment to support testing and fielding of modernized user equipment in support of the warfighter, MCEU will upgrade the AEP OCS, allowing it to task, upload and monitor M-Code within the GPS constellation. MCEU will provide command and control of M-Code capability to eight GPS IIR-M and 12 GPS IIF satellites currently on orbit, as well as future GPS III satellites.

 

COps Capabilities:

Following launch and check out, each future GPS III satellite will take its place in the GPS constellation. The COps modifications will allow the AEP OCS to support these more powerful GPS III satellites, enabling them to perform their positioning, navigation and timing missions for more than one billion civil, commercial and military users who depend on GPS every day. Besides the addition of GPS III, COps will also continue to support all the GPS IIR, IIR-M and IIF satellites in the legacy constellation.

Lockheed Martin has a long history of supporting ground systems, providing operations, sustainment and logistics support for nearly 60 Department of Defense satellites, including GPS, often allowing them to double their on-orbit operational design life.

Lockheed Martin also is currently under contract to develop and build ten GPS III satellites, which will deliver three times better accuracy and provide up to eight times improved anti-jamming capabilities. GPS III’s new L1C civil signal also will make it the first GPS satellite to be interoperable with other international global navigation satellite systems.

Thermal Vacuum Test

Engineers at Lockheed Martin recently proved their design for the world’s most powerful Global Positioning System (GPS) satellite can operate in and withstand the harsh conditions it will experience on orbit. On December 23, Lockheed Martin’s first GPS III satellite for the U.S. Air Force completed system-level Thermal Vacuum (TVAC) testing, validating the design of the entire assembled satellite. TVAC is a rigorous test designed to prove a satellite’s integrity and operational capabilities by subjecting it to prolonged cycles of simulated space temperature extremes in a special depressurized chamber.

The first GPS III satellite recently completed system-level Thermal Vacuum testing, validating Lockheed Martin’s design for the next generation of more powerful GPS satellites
The first GPS III satellite recently completed system-level Thermal Vacuum testing, validating Lockheed Martin’s design for the next generation of more powerful GPS satellites

«TVAC is the most comprehensive and perceptive test performed at the spacecraft level. If there is an issue with your design or production processes, you are going to find it here», said Mark Stewart, vice president of Lockheed Martin’s Navigation Systems mission area. «Successful completion of this significant test validates the thermal design of the spacecraft and verifies that all spacecraft components and interfaces operate at the temperature extremes of the space environment. We credit this performance to the Back to Basics work we performed earlier and the program’s unique GPS III Non-flight Satellite Testbed».

TVAC is the latest in a string of milestones for the first GPS III satellite. Last spring, the satellite’s major functional components were successfully integrated to form the first complete satellite. Last fall, the new satellite also successfully completed acoustic testing, where it was pounded with sound waves to simulate the vibrations it will endure during its launch.

With eight satellites under contract, the production line is now on a steady tempo at Lockheed Martin’s GPS III Processing Facility outside of Denver. The first four GPS III satellites are in various stages of assembly and test with most major components – including their structure and propulsion systems, solar arrays, and antennas – already delivered. This spring, with Harris Corporation’s delivery of its second navigation payload, the second GPS III satellite is expected to be integrated and begin environmental testing. Components for the next four GPS III satellites are already being assembled, tested and delivered on schedule by more than 250 aerospace industry companies from 29 states.

«We have a world class industry team supporting the development and production of GPS III for the Air Force and our nation», continued Stewart. «I thank them for their excellent work and commitment to this program».

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 to be interoperable with other international global navigation satellite systems.

The GPS III team is led by the Global Positioning Systems Directorate at the U.S. Air Force Space and Missile Systems Center. U.S. 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 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