Dr. Sun Hur-Diaz Receives 2008 Robert H. Goddard Exceptional Achievement Award

Dr. Sun Hur-Diaz, Emergent's Director of Guidance


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 TelescopeScience 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.