  An increasingly salient public policy challenge is how to manage the growing
number of satellites in orbit, including large constellations. Many policy
initiatives have been proposed that attempt to address the problem from
different angles, but there is a paucity of analytical tools to help
policymakers evaluate the efficacy of these different proposals and any
potential counterproductive outcomes. To help address this problem, this paper
summarizes work done to develop an experimental integrated assessment model --
Orbital Debris Propagators Unified with Economic Systems (OPUS) -- that
combines both astrodynamics of the orbital population and economic behavior of
space actors. For a given set of parameters, the model first utilizes a given
astrodynamic propagator to assess the state of objects in orbit. It then uses a
set of user-defined economic and policy parameters -- e.g. launch prices,
disposal regulations -- to model how actors will respond to the economic
incentives created by a given scenario. For the purposes of testing, the MIT
Orbital Capacity Tool (MOCAT) version 4S was used as the primary astrodynamics
propagator to simulate the true expected target collision probability ($p_c$)
for a given end-of-life (EOL) disposal plan. To demonstrate
propagator-agnosticism, a Gaussian mixture probability hypothesis density
(GMPHD) filter was also used to simulate $p_c$. We also explore economic policy
instruments to improve both sustainability of and economic welfare from orbit
use. In doing so, we demonstrate that this hybrid approach can serve as a
useful tool for evaluating policy proposals for managing orbital congestion. We
also discuss areas where this work can be made more robust and expanded to
include additional policy considerations.
