COMPARISON AND DESIGN OF SIMPLIFIED GENERAL PERTURBATION MODELS (SGP4) AND CODE FOR NASA JOHNSON SPACE CENTER, ORBITAL DEBRIS PROGRAM OFFICE A Graduate Project presented to the Faculty of California Polytechnic State University, San Luis Obispo In Partial Fulfillment of the Requirements for the Degree Master of Science in Aerospace Engineering by Nicholas Zwiep Miura May 2009 © 2009 Nicholas Zwiep Miura ALL RIGHTS RESERVED ii COMMITTEE MEMBERSHIP TITLE: Comparison and Design of Simplified General Perturbation Models (SGP4) and Code for NASA Johnson Space Center, Orbital Debris Program Office. AUTHOR: Nicholas Zwiep Miura DATE SUBMITTED: May 29, 2009 COMMITTEE CHAIR: Kira Abercromby, Ph.D COMMITTEE MEMBER: Eric Mehiel, Ph.D COMMITTEE MEMBER: Jordi Puig-Suari, Ph.D COMMITTEE MEMBER: Edwin Barker, Ph.D iii ABSTRACT Comparison and Design of Simplified General Perturbation Models (SGP4) and Code for NASA Johnson Space Center, Orbital Debris Program Office Nicholas Zwiep Miura This graduate project compares legacy simplified general perturbation model (SGP4) code developed by NASA Johnson Space Center, Orbital Debris Program Office, to a recent public release of SGP4 code by David Vallado. The legacy code is a subroutine in a larger program named PREDICT, which is used to predict the location of orbital debris in GEO. Direct comparison of the codes showed that the new code yields better results for GEO objects, which are more accurate by orders of magnitude (error in meters rather than kilometers). The public release of SGP4 also provides effective results for LEO and MEO objects on a short time scale. The public release code was debugged and modified to provide instant functionality to the Orbital Debris Program Office. Code is provided in an appendix to this paper along with an accompanying CD. A User’s Guide is presented in Chapter 7. iv ACKNOWLEDGMENTS I would like to thank my wife, Jesselle, for all her support throughout the year. Also, a special thanks to Dr. Abercromby, my thesis advisor, who provided excellent guidance and resources during the accelerated process. v TABLE OF CONTENTS LIST OF FIGURES........................................................................................................ x LIST OF TABLES ...................................................................................................... xiv LIST OF ACRONYMS .................................................................................................xv 1. Introduction ............................................................................................................... 1 2. Space Propagation Models......................................................................................... 2 3. SGP4 for Johnson Space Center................................................................................. 4 4. Procedure................................................................................................................... 6 4.1 Understanding the Software .................................................................................. 6 4.1.1 MATLAB Code ............................................................................................. 8 4.1.2 FORTRAN Code............................................................................................ 8 4.1.3 PREDICT Code.............................................................................................. 9 4.2 Analyzing Differences .......................................................................................... 9 4.2.1 Objects 8832, 25000, and 30000....................................................................11 4.2.2 Other Objects ................................................................................................13 4.3 Programming Deliverables...................................................................................13 5. Results.......................................................................................................................15 5.1 Data Points...........................................................................................................15 5.2 MATLAB vs. SATRAK ......................................................................................16 5.2.1 Object 8832...................................................................................................16 5.2.2 Object 25000.................................................................................................18 5.2.3 Object 30000.................................................................................................20 5.2.4 Analysis - MATLAB.....................................................................................22 vi 5.3 FORTRAN vs. SATRAK.....................................................................................23 5.3.1 Object 8832...................................................................................................23 5.3.2 Object 25000.................................................................................................25 5.3.3 Object 30000.................................................................................................27 5.3.4 Analysis - FORTRAN...................................................................................29 5.4 Modified Code vs. SATRAK ...............................................................................31 5.4.1 Object 8832...................................................................................................31 5.4.2 Object 25000.................................................................................................33 5.4.3 Object 30000.................................................................................................35 5.4.4 Analysis – Modified Code.............................................................................37 5.5 JSC Code vs. SATRAK .......................................................................................38 5.5.1 Object 8832...................................................................................................39 5.5.2 Object 25000.................................................................................................41 5.5.3 Object 30000.................................................................................................44 5.5.4 Analysis – JSC Code .....................................................................................45 5.6 Polysat.................................................................................................................46 5.6.1 CP3...............................................................................................................47 5.6.2 CP4...............................................................................................................50 5.7 ISS Tool bag ........................................................................................................50 5.8 Iridium Debris......................................................................................................52 5.9 Operational Issues................................................................................................53 5.9.1 Program Effectiveness...................................................................................53 5.9.2 Operational Speed .........................................................................................57 vii 6. Conclusion.................................................................................................................58 7. User’s Guide..............................................................................................................60 7.1 MATLAB ............................................................................................................60 7.1.1 Installation ....................................................................................................60 7.1.2 Verification Run............................................................................................61 7.1.3 TLE inputs ....................................................................................................62 7.1.4 Catalog Mode................................................................................................62 7.1.5 Manual Mode................................................................................................63 7.1.6 Understanding the Output File.......................................................................64 7.2 FORTRAN (Vallado Code)..................................................................................65 7.2.1 Installation ....................................................................................................66 7.2.2 Verification Run............................................................................................66 7.2.3 TLE Input......................................................................................................67 7.2.4 Catalog Mode................................................................................................67 7.2.5 Manual Mode................................................................................................67 7.2.6 Understanding the Output File.......................................................................69 7.3 Modified FORTRAN Code – For JSC..................................................................69 7.3.1 Installation ....................................................................................................69 7.3.2 Code Options ................................................................................................71