Prashant Patel, Institute for Defense Analyses; Daniel Scheeres, University of Colorado Boulder
Keywords: Reachability, maneuver, electric propulsion, space domain awareness
Abstract:
Incorporating reachability and maneuver envelopes into space situational awareness applications can help better identify targets, increase SSA asset utilization, and enable estimation of spacecraft thruster characteristics and propellent utilization.
Reachability estimates are valuable to space situational awareness (SSA) as they allow for automated searches and target identification. Reachability provides this benefit because it bounds the potential location a target object can be based on its initial location and its maneuver capability. Recently, we developed an algorithm that can estimate reachable trajectories and near-optimal non-reachable trajectories. Connecting reachable and near-optimal non-reachable trajectories allows us to map out the full maneuver envelope of a spacecraft while considering realistic thruster attributes, including mass loss. The algorithm has several attributes which make it potentially interesting for SSA applications.
The attributes we explore are the invariance of the control direction and thrust magnitude and mapping between mass and orbital shells. We also explore various reference frames to understand when one is better than another. The invariance of the control direction allows us to map out nested search shells as a function of potential thrust levels. This attribute provides an opportunity to optimize search volumes even when the target’s thrust level is not perfectly known.
The second attribute, mapping between mass and orbital shells provides an opportunity to estimate mass consumption and orbital reconstruction based on an observation. Our algorithm can provide a range of propellent consumed. A range is provided because we assume that the SSA assets have no knowledge of the control law used by the spacecraft.
Finally, we examine different reference frames over a set of common problems to see if one formulation is preferred over another. The reference frames we consider are inertial cartesian, relative Hill frame, and Keplerian elements (or variants of them). Early simulations indicate that different reference frames recover similiar information but we expect that some will outperform others in specific cases (e.g., multiple revolutions).
We run various numerical cases, report out algorithmic performance, and discuss the potential value, challenges, and limitations in their use. Using the numerical cases, we then explore possible use cases for SSA. The two potential cases we examine or one SSA asset with one target and a many to many situations (e.g., space traffic management).
Date of Conference: September 19-22, 2023
Track: Astrodynamics