Engineering topics

Lee, B. B.

Publications and source records attributed to Lee, B. B..

3 records

NASA NTRS1993

On-orbit performance of the Extended Gyrocompass Controller for the TOPEX/Poseidon spacecraft

The paper describes the Earth Acquisition Mode Extended Gyrocompass Controller flown aboard the NASA-CNES TOPEX/Poseidon Attitude Determination and Control Subsystem spacecraft for providing highly accurate measurements of the surface elevations over all the ocean basins. Particular attention is given to the on-orbit performance of the Extended Gyrocompass Controller used during quaternion initialization and Update Filter convergence processing, both of these procedures requiring maintenance of the spacecraft attitude control and knowledge. The development of the Extended Gyrocompass control technique is reviewed, and the results of the on-orbit yaw attitude control and knowledge performance provided by this algorithm are presented.

Sanneman, P. A.↗

NASA NTRS1991

Dynamic attitude command and control of the TOPEX/Poseidon spacecraft

The dynamic control laws utilized by the TOPEX/Poseidon (T/P) spacecraft attitude determination and control subsystem to command and maneuver the satellite during normal mission mode (NMM) laws are described. Results show that the vehicle is able to respond to the dynamic attitude commands while at the same time providing ample disturbance rejection capability.

Zimbelman, D. F.↗

NASA NTRS1989

Design of the TOPEX Earth Pointing Safe Hold Mode

A technical description of the design and analysis of the Earth Pointing Safe Hold mode (EPSHM) for the Ocean Topography Experiment (TOPEX) satellite is presented. The EPSHM serves as the primary hardwired analog backup controller for safe-haven satellite operations in the event of on-orbit anomalies. The EPSHM is a modified version of the baseline Multimission Modular Satellite (MMS) EPSHM used on the Landsat-4 mission. Modifications to the MMS baseline EPSHM used on Landsat-4 were required to satisfy the unique TOPEX operational requirements. One such TOPEX operational requirement is that the EPSHM provide a spacecraft yaw-axis slewing capability to maintain adequate illumination of the solar array. The EPSHM architecture, constituent hardware components, performance requirements and predicted on-orbit performance are described.

Dennehy, C. J.↗