Assessment of Spacecraft Systems Integration Using the Electric Propulsion Interactions Code (EPIC)

AIAA-2002-3667.docASSESSMENT OF SPACECRAFT SYSTEMS INTEGRATION USING THEELECTRIC PROPULSION INTERACTIONS CODE (EPIC)Ioannis G. Mikellides*, Robert A. Kuharski t, Myron J. Mandell*, Barbara M. GardnerScience Applications International CorporationSan Diego, CAABSTRACTSAIC is currently developing the Electric PropulsionInteractions Code "EPIC", an interactive computer toolthat allows the construction of a 3-D spacecraft model,and the assessment of interactions between itssubsystems and the plume from an electric thruster.EPIC unites different computer tools to address thecomplexity associated with the interaction processes.This paper describes the overall architecture andcapability of EPIC including the physics and algorithmsthat comprise its various components. Results fromselected modeling efforts of different spacecraft-thruster systems are also presented.INTRODUCTIONThe substantial economical advantages over chemicalsystems have established clear paths of applicability ofelectric propulsion for both near and far-earth missions.A critical engineering issue in their integration on-board spacecraft is the potentially unfavorableinteraction of their high-energy exhausts with thesurrounding subsystems. Such interactions may affectmission lifetime and sometimes even threaten missionsuccess. Their accurate assessment, within the design ofparticular spacecraft, is a complex task with nocomprehensive, stand-alone tools or guidelines tot thespacecraft designer in existence.As part of an effort sponsored by the SpaceEnvironment and Effects (SEE) Program at the NASAMarshall Space Flight Center, SAIC is currentlydeveloping the Electric Propulsion Interactions Code"EPIC", an interactive computer tool that allows theconstruction of a 3-D spacecraft model, and theassessment of interactions between its surfaces and theplume from an electric thruster. To carry out thecomplete interactions assessment process in anexpedited manner, EPIC unites different computer toolswhile allowing internal exchange of data under acommon interface. For example, calculation of theplume from an ion or Hall thruster is performed by a 2-D plume code that computes the expansion of the mainbeam using a fluid algorithm while resonant charge-exchange is determined using a Particle-in-Cell (PIC)method. "Plume maps" generated using differentsimulation tools, such as Direct Simulation MonteCarlo (DSMC) or Magnetohydrodynamic (MHD) codesmay also be easily incorporated into the 3-D tool. Themain component of EPIC is a 3-D code thatincorporates a variety of physical models for theassessment of interactions with the spacecraft includingsputtering, surface heating, and induced torques.EPIC CONCEPT AND ARCHITECTURE.The objective of EPIC is to design, develop andproduce an integrated modeling package for calculatingelectric propulsion plume interactions with spacecraftsystems. The suite of computer tools is designed toallow both expert and novice users to investigate EPplume-SIC interactions.In compliance with the current program guidelines, thecomputer tool (built for the Win32 platform) willconsist of the following main components:• An enhanced version of Object Toolkit, the 3-Dgeometry-definition tool developed for the NASACharging Analyzer Program (Nascap-2k), 1 tofacilitate interactive generation of the spacecraftgeometry and materials.* Senior Staff Scientist, SAIC, Member AIAA* Senior Staff Scientist, SAIC* Senior Staff Scientist, SAIC, Senior Member AIAA# Program Manager, SAICCopyright © 2001 The American Institute of Aeronauticsand Astronautics Inc. All rights reserved.