2007 Tycho Brahe Award
Recipient: Dr. Yoaz Bar-Sever
Citation: For outstanding contributions to the art of GPS satellite
orbits and signal modeling for high-accuracy spaceborne
navigation and science applications.
Dr. Yoaz Bar-Sever is a principal engineer
at NASA’s Jet Propulsion Laboratory, where he
currently is the program manager of the NASA
Global Differential GPS (GDGPS) System. For
nearly 20 years he has been involved in GPS
technology development and its scientific
applications. His key contributions cover the
areas of GPS orbit and signal modeling for precision terrestrial and
spaceborne GPS navigation. During this time he has written more
than 50 journal papers and conference articles and played a leadership
role in various activities of the International GNSS Service.
He is also a long-time member of The Institute of Navigation for
which he has repeatedly served as session chair.
The pioneering and innovative research of Dr. Bar-Sever in
the area of precision GPS orbit and signal modeling has enabled
cm level ephemeris products with numerous benefits for science
and navigation. His significant contributions to the art include:
identifying and solving the yaw attitude problem of GPS satellites
during eclipse season; developing and refining an empirical
approach to derive solar radiation forces for GPS satellites in orbit;
pioneering the estimation of antenna phase center offset of the
GPS satellites in orbit, showing large discrepancies with the official
pre-launch-calibrated values; improving the state of the art in
atmospheric sensing with GPS and GPS orbit determination accuracy
by introducing the atmospheric gradient model to GPS data
processing; leading the transformation of the GDGPS from a proofof-
concept prototype in 2000 to a fully operational system; and,
demonstrating signal in space for the new TDRSS Augmentation
Service for Satellites (TASS), extending GDGPS services to space to
enable precise real time navigation in Earth orbit. Dr. Bar-Sever is
currently leading the effort at NASA to enhance and operationalize
the TASS system.
Dr. Bar-Sever received a Ph.D. in Applied Mathematics from the
Technion - Israel Institute of Technology, and a Master in Electrical
Engineering from the University of Southern California.