Session
Session 8: Frank J. Redd Student Competition
Abstract
Terrestrial target tracking is performed by many communications and Earth observation missions to track groundfixed targets. Previous Space Flight Laboratory (SFL) missions have demonstrated target tracking with high pointing accuracy, enabled by the use of an on-board star tracker. The allowable target tracking trajectories for these missions is constrained by the need to point the star tracker away from the Sun and Earth, which often means operating with a restricted envelope of allowable targets. An additional issue affecting target tracking missions is the stictioninduced jitter associated with reaction wheel zero speed crossings. This paper presents the development of 3TECS, a software platform with the dual purpose of performing trajectory optimization to achieve minimum energy slews under star tracker exclusion constraints, and momentum setpoint optimization for reaction wheel zero-crossing placement. It is shown that, for SFL’s DAUNTLESS-class spacecraft, the trajectory planning results in the ability to track any target visible below the horizon with greater than 98:7% star tracker availability, across a wide range of orbits. Additionally, we show that the momentum setpoint planning provides low-jitter payload operation windows of greater than 160 s in duration. This is in contrast to the existing solution that can result in zero-crossing jitter directly coinciding with key payload operations.
Extending Target Tracking Capabilities through Trajectory and Momentum Setpoint Optimization
Terrestrial target tracking is performed by many communications and Earth observation missions to track groundfixed targets. Previous Space Flight Laboratory (SFL) missions have demonstrated target tracking with high pointing accuracy, enabled by the use of an on-board star tracker. The allowable target tracking trajectories for these missions is constrained by the need to point the star tracker away from the Sun and Earth, which often means operating with a restricted envelope of allowable targets. An additional issue affecting target tracking missions is the stictioninduced jitter associated with reaction wheel zero speed crossings. This paper presents the development of 3TECS, a software platform with the dual purpose of performing trajectory optimization to achieve minimum energy slews under star tracker exclusion constraints, and momentum setpoint optimization for reaction wheel zero-crossing placement. It is shown that, for SFL’s DAUNTLESS-class spacecraft, the trajectory planning results in the ability to track any target visible below the horizon with greater than 98:7% star tracker availability, across a wide range of orbits. Additionally, we show that the momentum setpoint planning provides low-jitter payload operation windows of greater than 160 s in duration. This is in contrast to the existing solution that can result in zero-crossing jitter directly coinciding with key payload operations.
