Description: Based on work done under Microcosm's recently completed Phase II SBIR program on X-ray pulsar based navigation (XNAV), relevant X-ray source characterization, X-ray detector measurement models, and source timing models will be developed to support eventual implementation in the GEONS flight software environment. In Phase I, an initial assessment will be made of the key model parameters and accuracy of time determination. Microcosm has recently been awarded a contract by DARPA to assess the potential for XNAV as a precision timing source for DoD missions. This work will be evaluated in Phase I for the potential to provide a precise, independent, X-ray pulsar-based time reference for NASA missions as well. The team will work with the Naval Research Lab, JHU/Applied Physics Lab, and NASA GSFC, focusing on sources and detectors to develop enhanced models, and assessing potential timing accuracy. Development of pulsar signal processing methods and prototype algorithms will continue, incorporating new source and detector models. This work, along with the previous Phase II effort, will further validate the utility of XNAV for NASA, and provide sufficient development and testing of relevant technology to provide a rapid path to a full flight software development in a Phase II program.

Benefits: The primary non-NASA XNAV applications would be to provide primary or secondary navigation services for DoD missions. For MEO, GEO, HEO, and even cis-lunar missions, where GPS has limited availability, XNAV can provide primary autonomous navigation capability. In addition, XNAV could provide an essential backup navigation capability for missions that normally rely on GPS, but have a need for continuity of operations in the event of loss or denial of GPS. These applications were being actively studied through DARPA's first XNAV program in 2004-06, and key Microcosm team members had strong ties to that program.

There are several promising NASA applications for XNAV, including missions beyond Jupiter as an enabling technology for autonomous navigation, potentially providing improved performance over standard DSN tracking capability for deep space missions, including the proposed Pioneer Anomaly and 500 AU missions. XNAV provides fully autonomous interplanetary navigation capability, potentially reducing the demands on DSN from increasing tracking requirements for future missions. XNAV can supplement DSN service and enhance DSN navigation performance. XNAV can also provide a backup navigation capability for manned and unmanned near-Earth, lunar, and Mars missions. Further, it can provide higher redundancy for manned missions. It can provide a highly accurate, independent time reference as well, for both Earth-orbiting and interplanetary missions.