Hopes are high for the next generation of the Global Positioning Satellite (GPS) system, known as GPS III. It promises to improve position, navigation, and timing services while providing advanced anti-jam capabilities. For example, the first GPS III satellites will deliver signals three times more accurate than current GPS spacecraft while providing three times more power for military users. In addition, a new civil signal will be interoperable with international global-navigation satellite systems (see photo).
And GPS III is now a step closer to fruition: Initial power has been turned on to the program's pathfinder spacecraft, thanks to work by the Lockheed Martin team developing this US Air Force system. Known as the GPS III Non Flight Satellite Testbed (GNST), this spacecraft is a full-sized prototype of the GPS III spacecraft. It will be used to identify and solve issues prior to the launch of the first GPS III space vehicle. The GNST is populated with fully functional, non-flight boxes. As a result, it will provide the following: space-vehicle design-level validation; early verification of ground, support, and test equipment; and early confirmation and rehearsal of transportation operations.
To support the phased checkout of the integrated design, the GPS III team has installed power-subsystem components; harnesses and tracking; telemetry; and control hardware on the GNST structure. In addition, flight software versions have been delivered for all of the spacecraft and payload computer processors. GPS III teammate ITT is simultaneously integrating the GNST Navigation Payload at its facility in Clifton, NJ.
Aside from demonstrating initial mechanical integration, the successful powering on of the GNST validates its interfaces. It also paves the way for electrical and integrated hardware-software testing. Later this year, the GNST will be shipped to Lockheed Martin's GPS III Processing Facility in Denver to demonstrate assembly, integration, and test procedures. It will then be delivered to Cape Canaveral Air Force Station in summer 2012 for pathfinding activities at the launch site. Having powered on its full-sized prototype of the GPS III spacecraft, the program team is confident that it will meet the scheduled launch of the first GPS III satellite in 2014.
By starting with the GNST, this program is significantly reducing risk, improving production predictability, increasing mission assurance, and lowering overall costs. Building on lessons learned from previous GPS space programs, many consider the US Air Force's GPS III acquisition approach to be the model for future space acquisition. The program has reinstated rigorous technical specifications and standards. It also places strong emphasis on systems engineering with a robust mission-assurance process. These actions provide the basis for verifying the quality of the technical work while ensuring that issues are found and corrected earlier in the program.