Dr. Sun Hur-Diaz Receives 2008 Robert H. Goddard Exceptional Achievement
Award
Greenbelt, MD, September 17, 2008
Dr. Sun Hur-Diaz, Emergent's Director of Guidance, Navigation and Control, was
awarded the 2008 Robert H. Goddard Exceptional Achievement Award for her
outstanding technical insight and leadership in the design of new Hubble Space
Telescope Science and Safing System control modes.
Exceptional Achievement Award Criteria
Beginning in 2008, the NASA Goddard Space Flight Center developed the Robert H.
Goddard Awards to combine its former Awards of Excellence and the Goddard Honor
Awards. The objective of the Exceptional Achievement Award is to recognize
individuals and teams who make significant contributions to the performance of
the Center's mission, which aid the Center's scientific, technical, and
institutional capabilities, and enhances mission performance. Accomplishments
must be significantly above job expectations as demonstrated by its
significance, creativity, or uniqueness, and often exceptional performance
sustained over a significant period of time. The scope and significance are to
be determined relative to the skill group and grade level of the nominee's
peers, or in the case of teams, similar team activities.
Dr. Sun Hur Diaz's Role in the HST Life Extension Initiative
Over the past three years, Dr. Sun Hur-Diaz has provided outstanding support to
the Hubble Space Telescope (HST) Project Life Extension Initiatives Program by
leading the design effort for three major and complex control modes for HST. Dr.
Hur-Diaz applied the Kalman Filter formalism to the attitude-hold and maneuver
control for the new One Gyro Science (OGS) Operations mode. Her algorithm suite,
named "Universal Kalman Filter or UKF" provides estimates of the attitude error
and gyro-less plane rate errors given varied sensor inputs in lieu of the
missing gyro data. Sensor inputs can include Magnetic Sensing System data,
Coarse Sun Sensor data, and zero or more gyros. Her design was so robust and
flexible that Dr. Hur-Diaz used UKF as the basis for the new Kalman Filter Sun
Point (KFSP) Safemode and for a suite of feasibility studies of Reduced-Gyro
Reduced-Wheel (RGRW) Sun Point Safe Modes.
The development of KFSP and design
of the RGRW safe-mode control laws provide a vastly improved reduced asset
control capability to the HST safing system and significantly reduce the risks
associated with reduced asset safe mode entries. The on-orbit performance of
both OGS and KFSP was tested in January 2008 with outstanding success. All
performance requirements were either met or exceeded. Maximum attitude
excursions of 3 degrees or fewer were measured during the maneuver and attitude
hold modes in a variety of orbital conditions. KFSP provides robust three-axis
attitude control during orbit night, reduces attitude excursions during a safing
incident, and offers better battery charge status thus reducing the need for
power load shed. The One-Gyro Science Capability and the KFSP Safe-Mode will one
day extend the mission life of HST.
In addition to the algorithm design and
development, Dr. Hur-Diaz ran thousands of simulations, prepared several peer
reviews, contributed to the OGS/KFSP PDRs and CDRs, and authored/co-authored
four significant engineering reports. Most recently, she completed a peer review
and engineering report on a Two-Reaction Wheel Science capability for HST. Her
contributions to the HST Project have been critical for extending the mission
life of HST. "I cannot tell you what an honor it has been to work with Sun and
to facilitate her phenomenal achievements for HST" said Dr. Olivia, HST
Instrument Operations and Life Extension Initiatives Manager.
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