TECHNOLOGY DIGEST - Draper Laboratory

Autonomous Mission Management for Spacecraft Rendezvous
Using an Agent Hierarchy
Mark Jackson, Christopher D'Souza, Hobson Lane
Copyright © 2005 by The Charles Stark Draper Laboratory, Inc. Presented at Infotech@Aerospace. Arlington, VA,
September 26-29, 2005
INTRODUCTION
An agent-based autonomous mission manager for spacecraft is developed and applied to a spacecraft
rendezvous problem. The mission manager monitors, plans, and executes rendezvous activities
for a chaser satellite with low-thrust and high-thrust effectors. The software is based on a hierarchy of
“activity agents,” each of which plans, monitors, executes, and replans an activity. These activity agents
are instantiated and scheduled by a software framework capable of reconfiguring the agent hierarchy
when replanning occurs. Targeting and planning algorithms are incorporated into the agent hierarchy
to orchestrate a rendezvous with an orbiting spacecraft. These algorithms make use of low-thrust guidance
to arrive in the neighborhood of the target, followed by a series of high-thrust burns to arrive at
a specified offset point at a specified time. During both the low-thrust and high-thrust activities, the
mission manager monitors subsystem status as well as the relative navigation state of the chaser. When
low-thrust failures occur, the manager completes the rendezvous by scheduling additional high-thrust
burns. The mission manager, along with low- and high-thrust guidance algorithms, is implemented in
simulation. A demonstration of several replanning events – both failure and error driven – is provided
with 3-dimensional (3D) graphics as well as an “agent activity” display that depicts the active agents
and shows the hierarchy reconfiguration process when replans occur.
The next 10 to 20 years are likely to see an increasing need
for spacecraft capable of autonomous rendezvous with
other spacecraft or space objects. The National
Aeronautics & Space Administration (NASA) is currently
developing a set of exploration vehicles, both manned and
unmanned, to accomplish several missions, including
International Space Station (ISS) crew exchange, ISS
resupply, lunar transit and landing, lunar return, and
ultimately, Mars exploration. These missions will all
require spacecraft rendezvous and docking in various
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orbital environments, including low Earth orbit, lunar
orbit, Martian orbit, and possibly, rendezvous and docking
at or near Lagrange points. Additionally, there is significant
military and commercial interest in satellite rendezvous for
resupply, intelligence, and other operations.
Many of these operations will be conducted by unmanned
spacecraft in arenas for which close ground contact and
supervision are neither practical nor desirable. Spacecraft
will be required to autonomously plan rendezvous maneuvers,
monitor navigation and subsystem status, diagnose