Launch vehicle tracking enhancement through global positioning system metric tracking

United Launch Alliance (ULA) and their United States Air Force (USAF) Evolved Expendable Launch Vehicle (EELV) customer initiated operational flights of both the Atlas V and Delta IV launch vehicle families in 2002. Both Launch Vehicle families have provided 100% mission success since their respective inaugural launch and have demonstrated launch capability from both Vandenberg Air Force Base (VAFB) on the Western Range and Cape Canaveral Air Force station (CCAFS) on the Eastern Test Range. However, the current EELV fleet communications, tracking, and control architecture & technology, which date back to the origins of the space launch business, requires costly MIL/Space rated parts. The United States Air Force and United Launch Alliance have embarked on initiatives to significantly reduce the cost of launch systems by strategically using Commercial Off The Shelf components (COTS). A significant milestone in these initiatives is implementation and certification for use of Global Positioning System (GPS) Tracking Unit (GTU) developed by ULA and Space Vector Corporation (SVC) on launch vehicles that makes use of COTS components. While the main purpose of GPS Metric Tracking (MT) system was to leverage the existing GPS satellite based navigation system's capability in order to significantly reduce the costs of Test Range O&M it was important to reduce total Launch Vehicle system implantation cost as well. ULA, in partnership with the U.S. Government, engaged in a project plan to evolve the EELV fleet to a Space Based Range operational concept utilizing cost saving COTS parts to keep total system implantation cost low. The GTU provides precise launch vehicle position, velocity and timing information that can replace ground radar tracking resource functionality while utilizing COTS components to reduce costs and increase capabilities. The availability of military grade components often limits system design and functionality. The GTU is designed to incorporate some of the most current commercial parts available that offer features not found in military components. These COTS components brought with them additional issues due to a lack of performance data in the launch vehicle environment for these new components. Space Vector Corporation utilized a stackable, modular design in developing the GTU for EELV. This approach allows for changes and upgrades to components within a specific module without adversely affecting the entire unit. The modular approach to the GTU design also allowed Space Vector Corporation to provide additional interfaces to accommodate both Atlas V and Delta IV unique power and ground interfaces requirements into a single unit eliminating the need to develop separate configurations for each vehicle within the EELV family. The GTU also took advantage of an existing COTS receiver and processor that were ruggedized for the launch vehicle environments. The GTU completed all qualification testing in May 2011. The GPS MT system successfully passed all certification flights and was certified for use on both the Atlas and Delta launch vehicles for both East Range and West Range in 2013 and 2014. This paper summarizes the design approach and the implementation of COTS components in a launch vehicle environment. This effort required creating new manufacturing methodologies and test processes to ensure reliability requirement of space borne launch vehicles.