Crosslink Summer 2002 Contributors

Charting a Course Toward Global Navigation

Steven R. Strom is the corporate historian for Aerospace. He holds an M.A. in American history from Boston College and has completed all of the work toward his Ph.D. in history at Rice University except for his dissertation. He is the author of A Perfect Start to the Operation: The Aerospace Corporation and Project Mercury, which appeared in the Summer 2001 issue of Crosslink (steven.r.strom@aero.org).

Operation and Application of the Global Positioning System

Colleen H. Yinger, Senior Engineering Specialist, Navigation and Geopositioning Systems Department, has more than 15 years of experience in GPS performance and applications. She has supported the GPS Joint Program Office in the areas of architecture analysis, control-segment enhancements, atmospheric compensation, augmentation systems, military and space applications, and precise timing. She joined Aerospace in 1978. She holds an M.S. in mechanical engineering from the University of California, Los Angeles (colleen.h.yinger@aero.org).

Optimizing Performance Through Constellation Management

Paul D. Massatt is Senior Engineering Specialist in the Navigation and Geopositioning Systems Department. He began analyzing GPS constellation performance when he joined Aerospace in 1985 and subsequently developed the nonuniform 24-satellite constellation that defines GPS nominal orbits today. His analyses of constellation buildup, launch placement, anomaly resolution, and system innovations have defined most of the orbital positions of the GPS satellites since the 1980s and have helped the Air Force manage the constellation and define future system requirements and architectures. He holds a Ph.D. in applied mathematics from Brown University (paul.d.massatt@aero.org).

Wayne Brady joined Aerospace in 1979. Until his retirement, he served as Director of the Mission Modeling and Simulation Office. He holds M.S. degrees in mechanical engineering and management science from the University of Southern California. He lives in Oregon.

Orbit Determination and Satellite Navigation

John Langer, Senior Project Leader, Global Positioning System, has been with Aerospace for more than 15 years. He specializes in orbit determination and GPS, with particular focus on space applications of GPS. Before joining the GPS program office, he managed the Orbit Determination Section of the Navigation and Geopositioning Systems Department. He holds an M.S. in mathematics from the University of Washington (john.v.langer@aero.org).

Thomas D. Powell is Project Engineer in the GPS Military User Equipment Directorate, supporting the GPS Joint Program Office. He holds a Ph.D. in aerospace engineering from the University of California, Los Angeles. For the past seven years, he has monitored the development of receivers and processing techniques for spacecraft users of GPS. He also supports the Digital Advanced GPS Receiver program, which is procuring a new generation of handheld GPS receivers for the Army (thomas.d.powell@aero.org).

John Cox, Senior Engineering Specialist, Navigation and Geopositioning Systems Department, has participated in numerous satellite navigation and astrodynamic system analyses and development efforts. He holds a B.S. in physics from Tufts University and has been with Aerospace since 1984. He spent five years in the Milstar program office before joining the Navigation and Geopositioning Systems Department (john.cox@aero.org).

GPS/Inertial Navigation for Precise Weapon Delivery

Antijamming and GPS for Critical Military Applications

Anthony Abbott is Principal Engineer in the GPS III and Military Applications Directorate, supporting the GPS Joint Program Office in advanced antijam technology and user equipment architecture. He joined Aerospace in 1968, and helped develop the conceptual definition of System 621B, the predecessor to GPS. He also contributed to the design and analysis of numerous satellite programs, including Phase I GPS, while a section manager in the Controls Department. He left Aerospace in 1976 to join Magnavox as a senior staff engineer for GPS Phase I user equipment, participating in the design, integration, and field testing of the first unaided and INS-aided GPS sets, including the first weapon-delivery system fully integrated with GPS. In 1982, he joined Northrop Grumman as the chief analyst on the B-2 navigation system and later on the B-2 GPS-Aided Targeting System and GPS-Aided Munition. He returned to Aerospace in 1997. He has an M.S.E.E. from the University of Southern California in system science and holds three U.S. patents (with two more pending) and one international patent. He received the Engineers' Council Merit Award in 1997 for participation in the B-2 GPS-Aided Targeting System (anthony.s.abbott@aero.org).

Modernization and the Move to GPS III

Steven Lazar is Systems Director for GPS III in the Weather and Navigation Division. He has more than 21 years of experience in radio-frequency and antenna applications in space and ground systems, signal design and test for radio-navigation systems, and spectrum management. He has been in the GPS program office since 1989. He has an M.S. in electrical engineering from the University of California, Los Angeles. He received The Aerospace Corporation President's Award in 1998 for his work in helping to invent a new signal structure for GPS. He is the author of more than 20 papers and holds one U.S. patent (steven.lazar@aero.org).