Multi-agent Modeling and Simulation Approach for Design and Analysis of MER Mission Operations

A space mission operations system is a complex network of human organizations, information systems, deep-space communication systems and spacecraft hardware. As in other organizations, one of the problems in mission operations is managing the relationship of the mission information systems to how people actually work (practices). Brahms, a multi-agent modeling and simulation tool, was used to model and simulate NASA’s Mars Exploration Rover (MER) mission operations work practice. The objective was to investigate the value of work practice modeling for mission operations design. From spring 2002 until winter 2003, the first author participated in mission operations design sessions and observed operations field tests for the MER mission held at Jet Propulsion Laboratory (JPL). We discuss mission operations designers’ interaction with the Brahms tools, their reactions to the simulation output during model validation and our work on modeling computer systems and people’s interaction with systems. This project spurred JPL’s interest in the Brahms model, but it was never included as part of the formal mission operations design process. We discuss why this occurred. We also suggest how Brahms might have been used differently to reveal human-computer interaction problems with operations software, which emerged in training exercises and during the mission. 1. BRAHMS Brahms was conceived as a business process modeling and simulation tool that incorporates the social systems of work, thus illuminating how formal process flow descriptions relate to people’s actual located activities in the work place [1-2]. Brahms consists of an agent-based modeling language and simulation environment called the Brahms Integrated Development Environment (IDE) [3]. The Brahms Composer (Figure 1), part of the IDE, offers various connected design views that are based on the World Modeling Framework [4], including: organization/people, artifact/system, data/information, geography/location, communications, activity/task and timing/flow. These design views hierarchically present concepts such as agent groups, objects and geography, etc. for convenient access. The Composer’s multiple views also allow a modeler to graphically create and edit concepts; these are automatically converted into the Brahms modeling language for simulation. Geography Classes and Objects Groups and Agents Activities Workframes Thoughtframes Beliefs and Facts Figure 1. Brahms Composer The Brahms Agent Viewer (Figure 2), another part of the IDE, provides the simulation visualization. The visualization shows a chronological history of what activities are performed by people or robots, usage of tools and systems and communication between people, robots and systems. Figure 2. Brahms Agent Viewer: Behaviors are modeled as conditional actions (Workframes) organized hierarchically into Activities. Locations, Communications, actions (Primitive Activities), and Objects touched by Agents are represented on a timeline. 2. MARS EXPLORATION ROVER (MER) MISSION MER is a dual-robot, Mars surface mission. With a complement of remote sensing and in-situ science instruments, scientists seek to determine the history of climate and water at a site on Mars where conditions may once have been favorable to life. Both rovers, Spirit and Opportunity, landed safely in the early part of 2004. The Jet Propulsion Laboratory (JPL) in Pasadena, CA, started twenty-four hour, round-the-clock mission operations; after the first three months, JPL scaled back operations to a roughly eight hours a day schedule. 3. BRAHMS MODEL OF MER The task of the MER mission operations designers was to integrate legacy systems with newly developed systems plus set up work processes for scientists and engineers in three shifts during a twenty-four hour period. In late 2002, the first author participated in JPL’s mission operations design meetings and researched the mission operations design documentation. He interviewed key MER team members, asking them to describe their future MER mission operations job activities, information needs, interfaces and tools. From this data and a model previously created for a lunar mission (Victoria), we created an initial MER mission operations model and simulation in Brahms [5]. 3.1