Paul Zetocha

The Techsat-21 autonomous space science agent

The Autonomous Sciencecraft Experiment (ASE) will fly onboard the Air Force TechSat-21 constellation of three spacecraft scheduled for launch in 2004. ASE uses onboard continuous planning, robust task and goal-based execution, model-based mode identification and reconfiguration, and onboard machine learning and pattern recognition to radically increase science return by enabling intelligent downlink selection and autonomous retargeting. In this paper we discuss how these AI technologies are synergistically integrated in a hybrid multi-layer control architecture to enable a virtual spacecraft science agent. We also describe our working software prototype and preparations for flight.

Commanding and controlling satellite clusters

Many organizations, including the National Aeronautics and Space Administration (NASA) and the US Department of Defense, want to use constellations or fleets of autonomous spacecraft working together to accomplish complex mission objectives. At the Air Force Research Laboratorys Space Vehicles Directorate, we are developing architectures for commanding and controlling a cluster of cooperating satellites through autonomous software development for the TechSat 21 program. Large clusters of satellites flying in formation must have some level of onboard autonomy in order to: fly within specified tolerance levels; avoid collisions; address fault detection, isolation, and resolution (FDIR); share knowledge; and plan and schedule activities. Commanding and controlling a large cluster of satellites can be very burdensome for ground operators as well. The article describes efforts to address these issues through the technology development for TechSat 21.

Development of a testbed for distributed satellite command and control

At the Air Force Research Laboratorys Space Vehicles Directorate we are investigating and developing architectures for commanding and controlling a cluster of cooperating satellites through prototype development for the TechSat-21 program. The objective of this paper is to describe a distributed satellite testbed that is currently under development and to summarize near term prototypes being implemented for cluster command and control. To design, develop, and test our architecture we are using eight PowerPC750 VME-based single board computers, representing eight satellites. Each of these computers is hosting the OSE/sup TM/ real-time operating system from Enea Systems. At the core of our on-board cluster manager is ObjectAgent. ObjectAgent is an agent-based object-oriented framework for flight systems which is particularly suitable for distributed applications. In order to handle communication with the ground as well as to assist with cluster management, we use the Spacecraft Command Language (SCL). SCL is also at the centerpiece of our ground control station and handles cluster commanding, telemetry decommutation, state-of-health monitoring, and Fault Detection, Isolation, and Resolution (FDIR). For planning and scheduling activities we are currently using ASPEN from NASA/JPL. This paper describes each of the above components in detail and then presents the prototypes being implemented.

A backroom mission operations center for TechSat 21

The TechSat 21 satellite program is an Air Force Research Laboratory (AFRL) technology initiative which has an objective to demonstrate and validate microsatellite cluster system concepts and enabling technologies. The primary experimental objectives are to demonstrate formation flying algorithms and technologies for clustered satellites, and to demonstrate autonomous cluster and spacecraft operations. TechSat 21 consists of three satellites which will fly in various configurations with variable separation distances. Command and control of a cluster of satellites with multiple heterogeneous experimental objectives poses several challenges from a ground perspective. To assist in operating TechSat 21, AFRL is developing a backroom Mission Operations Center (MOC) which will be capable of performing, among other tasks: planning and scheduling; command generation; state-of-health (SOH) monitoring; telemetry playbacks; fault detection, isolation, and resolution (FDIR); data storage; and payload data analysis. The objective of this paper is to describe the MOC architecture, highlight the key components, and outline its planned operational use.

Intelligent Planning Systems for Space Resiliency

The Air Force Research Laboratory is leading research to improve the resiliency of space systems through the design of autonomous planning systems to avoid, work through, recover quickly, and minimize the effects of on-orbit events. This has involved the application of planning systems research from the Artificial Intelligence field to the unique requirements of remote systems with limited sensing and communication capabilities. Multiple planning agents and approaches are being integrated into a coherent threat response planner. This resiliency planner is being designed to interface directly with traditional flight software so that on-orbit demonstrations can be performed in the future.

Command and control displays for space vehicle operations

This paper shall examine several command and control facility display architectures supporting space vehicle operations, to include TacSat 2, TacSat 3, STPSat 2, and Communications Navigation Outage Forecasting System (CNOFS), located within the Research Development Test & Evaluation Support Complex (RSC) Satellite Operations Center 97 (SOC-97) at Kirtland Air Force Base. A principal focus is to provide an understanding for the general design class of displays currently supporting space vehicle command and control, e.g., custom, commercial-off-the-shelf, or ruggedized commercial-off-the-shelf, and more specifically, what manner of display performance capabilities, e.g., active area, resolution, luminance, contrast ratio, frame/refresh rate, temperature range, shock/vibration, etc., are needed for particular aspects of space vehicle command and control. Another focus shall be to address the types of command and control functions performed for each of these systems, to include how operators interact with the displays, e.g., joystick, trackball, keyboard/mouse, as well as the kinds of information needed or displayed for each function. [Comparison with other known command and control facilities, such as Cheyenne Mountain and NORAD Operations Center, shall be made.] Future, anticipated display systems shall be discussed.