IV&V of three astrodynamics functions of the Satellite Tool Kit

Abstract

This paper presents the results of an Independent Verification and Validation (IV&V) of three astrodynamics functions of the Satellite Tool Kit (STK) of Analytical Graphics, Inc. The three functions are: (1) high precision orbit propagator (HPOP), (2) parameter and coordinate frame transformations, and (3) access and visibility calculations. The Aerospace Corporation's trajectory and orbit determination program (TRACE) was used as the benchmark tool for conducting tests for functions (1) and (2). Other Aerospace Corporation programs—Rotate, Geo, SOAP and ASTROLIB—were used for testing the STK access and visibility calculations. The agreements between STK-generated satellite ephemeris or orbit parameters and those generated by Aerospace Corporation programs varied with individual task conditions. A single quantitative statement cannot be made for all testing. Based on Aerospace experience, results ranged from satisfactory to excellent. Some limited areas had larger than expected differences, but those differences were deemed small for most applications, with the exception of those involving precision geodesy or altimetry work. The Aerospace Corporation programs mentioned above have been used to validate several Department of Defense (DOD) mission operation and support software systems. The quality of the three STK functions is reflected by the test results of this IV&V, shown in this paper. It is up to the users to determine the adequacy of STK v4.1.0 for their specific applications. INTRODUCTION This paper documents the results of an Independent Verification and Validation (IV&V) of specified functions of the Satellite Tool Kit (STK) of Analytical Graphics, Inc. (AGI). This first phase of the IV&V of STK is focused on three astrodynamics functions: (1) high precision orbit propagator (HPOP), (2) parameter and coordinate frame transformations, and (3) access and visibility calculations. The Aerospace Corporation's trajectory analysis and orbit determination program TRACE v2.4.9 was used as the benchmark tool for conducting tests for functions (1) and (2). Other Aerospace Corporation programs—Rotate vl.O, Geo vl.O, SOAP v9.2.2 and ASTROLIB (1999 Version)— were used for testing the STK coordinate frame transformations, access and visibility calculations. All of the IV&V testing was made against the released version of 4.1.0 of STK. Detailed descriptions of the approach, methods, tools and results are provided in Reference 1. The following sections summarize the test and results of the three astrodynamics functions. HIGH PRECISION ORBIT PROPAGATOR (HPOP) This section describes the Independent Validation and Verification (IV & V) tests performed on the High Precision Orbit Propagator (HPOP) used in the Satellite Tool Kit v4.1.0 (STK), a set of satellite analysis software tools developed by Analytical Graphics, Inc. The Aerospace Corporation's Trajectory Analysis and Orbit 'Senior Engineering Specialist, Astrodynamics Department, AIAA Associate Fellow P.O. Box 92957, M4-948 Work: 310/336-4295 FAX: 310/336-5827 Los Angeles, CA 90009-2957 email: chia-chun.chao@aero.org Engineering Specialist, Senior Engineering Specialist, Manager, Satellite Navigation Department ^Senior Engineering Specialist, Engineering Specialist, Reconnaissance Systems Division Chief Orbital Scientist, AIAA Senior Member Copyright @2000 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.