CR 114745 AAIL-AbLE T1E PU6BLlc (NASA-CR-114745) STUDY OF SPIN-SCAN 174-21801 IMAGING FOR CUTER PLANETS MISSIONS Final Technical Report (Santa Barbara Research Center) 289 p BC $17.50 Unclas CSCL 17B G3/07 37624_ FINAL TECHNICAL REPORT STUDY OF SPIN-SCAN IMAGING FOR OUTER PLANETS MISSIONS Contract No. NASZ-7096 For - National Aeronautics and Space Administration OAST Systems Studies Division Ames Research Center Moffett Field, California By - Santa Barbara Research Center and Lunar and Planetary Laboratory/University of Arizona SANTA BARBARA RESEARCH CENTER --- A Subsidiary of Hugkes Aircralt Compqay L __ .-. SANTA BARBARA RESEARCH CENTER A Subsidiary ol Hughes Aircraft Company 75 COROMAR DRIVE *GOLETA I CALIFORNIA FINAL TECHNICAL REPORT STUDY OF SPIN-SCAN IMAGING FOR OUTER PLANETS MISSIONS Contract No. NAS2-7096 For National Aeronautics and Space Administration OAST Systems Studies Division Ames Research Center Moffett Field, California Original Draft Submitted 21 September 1973 Final Report Published 27 February 1974 Prepared by: E.E. Russell M. G. Tomasko Member of Technical Staff Research Associate SBRC Systems Analysis Lunar and Planetary Laboratory R.A. Chandos University of Arizona Member of Technical Staff SBRC Electronics Approved by: J.C. Kodak Member of Technical Staff E.E. Russell, Study Manager SBRC Mechanics S. F. Pellicori __ ___ Member of Technical Staff R. F. Hummer, Manager SBRC Optics o Electro-Optical Instrumentation I SBRC AC KNOW LEDGEMENT S The authors wish to acknowledge the technical assistance of other members of the staff at SBRC during the course of this study. In addition, many people at the University of Arizona have contributed substantially to this report. We are grateful for Mr. N. D. Castillo's invaluable program- ming assistance throughout the study. Special recognition is also due Mr. C. E. KenKnight for his work on subsection 4. 3, and Mr. L. Doose and Mr. A. E. Clements for developing many of the techniques of Section 8. The rectification programs of Section 8 were originally developed under the supervision of Dr. W. Swindell of the Optical Sciences Department of the University of Arizona for the Pioneer Jupiter Program. Finally, the assistance "of Ames Research Center personnel and, in particular, of the technical monitor, Mr. L. Edsinger, is gratefully acknowledged. SANTA BARBARA RESEARCH CENTER SBRC CONTENTS Section Page 1 SUMMARY OF STUDY RESULTS ...... ...... 1-1 1. 1 Scope of Study ........................... 1-1 1. 2 System Modeling Methodology .................... 1-3 1. 3 Optimized Designs for Jupiter Orbiter Mission ....... 1-4 1.4 Image Sequencing and Processing .... ............ 1-6 1. 5 Recommendations for Future Effort .............. 1-6 2 INTRODUCTION TO SPIN-SCAN IMAGING .............. 2-1 2. 1 Prior History ...... .......................... 2-1 2. 2 Basic Concepts ........... .... .............. 2-2 2. 3 Scope of Study Effort ..... ............ .......... 2-4 3 IMAGER CONSTRAINTS ........................ ...... 3-1 3. 1 Science Imposed Constraints ...... .... ......... 3-1 3. 1. 1 Resolution ............... .. ......... 3-1 3. 1.2 Signal-to-Noise Ratio ........................... 3-3 3. 1. 3 Modulation Transfer Function and Aliasing .. .......................... 3-8 3.1.4 Underlap . .......................... 3-16 3. 1. 5 Scene Characteristics ...................... 3-20 3. 1. 6 Spectral Coverage ..................... 3-24 3. 1. 7 Spatial Coverage ...................... 3-26 3. 1. 8 Geometrical Accuracy . 3-26 3. 1. 9 Quantization Accuracy and Dynamic Range . ... ...... ........ .. .. .... 3-26 3. 2 Spacecraft Imposed Constraints . ................ 3-28 3. 3 Additional Constraints ...... ................. .. 3-29 SANTA BARBARA RESEARCH CENTER iii SBRC CONTENTS (Continued) Section Page 4 DATA HANDLING AND RECONSTRUCTION ............. 4-1 4. 1 Data Handling, Storage, and Telemetry ............. 4-1 4. 2 Data Compaction ........................... 4-2 4. 3 Image Reconstruction ..... ..................... 4-12 4. 3. 1 Geometry of Spin-Scan Imaging .............. 4-13 4. 3. 2 Assignment of Intensities to Display Array. ... 4-22 4. 3. 3 Summary ............ .......... .... 4-35 5 IMAGER COMPONENTS ........................... 5-1 5. 1 Detectors ........ .. ...................... 5-1 5. 1. 1 Photoemissive Detectors .. ............... 5-1 5. 1.2 Silicon Photodiode Array Detectors ......... 5-11 5. 1. 3 Other Candidate Detectors ................ 5-18 5. 1.4 Detector Radiation Effects .... ...... ...... 5-22 5. 1. 5 Signal-to-Noise (SNR) Equations . 5-37 5.2 Scan Mechanism . ............ .... ......... 5-45 5. 2. 1 Image-Space Scanning . 5-45 5. 2. 2 Object-Space Scanning ... .... .... .. 5-46 5.3 Mechanics. ........... ...... ... ......... 5-48 5. 3. 1 Basic Design Approaches . .... 5-48 5. 3. 2 Material Selection ........... .......... 5-49 5.4 Telescope Optics ............................ 5-50 5. 4. 1 Requirements for the Telescope . ........ ... 5-50 5.4. 2 Image-Quality Analysis ... .. .......... 5-51 5. 4. 3 Restrictions on Fundamental Design Param eters ......................... 5-52 5. 4. 4 Defocus and Alignment Error Tolerances ..... 5-52 5. 4. 5 Selection of Radiation-Resistant Optical M aterials ............... ......... 5-67 SANTA BARBARA RESEARCH CENTER iv SBRC: CONTENTS (Continued) Section Page 5 5. 5 Electronics ............................... 5-72 5. 5. 1 Component (Cont) Selection. ..... ............. 5-72 5. 5. 2 Electronic Packaging ................... 5-73 6 SYSTEM MODELING ............................ 6-1 6. 1 Parametric Analysis ........................ 6-1 6. 1. 1 Summary of Constraints ................. ' 6-1 6. 1. 2 Modeling Nomographs . .................. 6-4 6. 2 Application to Jupiter ........................ 6-10 6. 3 Application to Other Outer Planet Missions . ........ 6-17 6. 3. 1 Saturn/Uranus Mission: Uranus Encounter . 6-18 6. 3. 2 Saturn/Uranus Mission: Saturn Encounter .... 6-23 7 POINT DESIGN FOR JUPITER ORBITER . .............. 7-1 7. 1 System Design ............................. 7-1 7. 1. 1 Imager Point Design Assumptions . ........ 7-1 7. 1. 2 Functional Operation . .................. 7-5 7.2 Electronic Design .......................... 7-8 7. 2. 1 Preamplifiers ............... .. .... 7-8 7. 2. 2 High-Voltage Supply ... ............... 7-9 7.2. 3 Analog Channel Electronics . .............. 7-10 7.2.4 Analog Processing ............... .. .. 7-13 7.2. 5 Data Handling ........................ 7-15 7.2. 6 Logic Design. ............... ..... .. 7-17 7.2.7 Telescope Control Electronics . ........ 7-18 7. 2. 8 Calibration Circuitry ................... 7-20 7. 2. 9 Electronics Weight ..................... 7-22 SANTA BARBARA RESEARCH CENTER v SBRC CONTENTS (Continued) Section Page 7 7. 3 Telescope Optical Designs .... 7-22 (Cont) 7.3. 1 Point Designs 1 and 3 .............. ..... 7-25 7. 3. 2 Alternate Point Design 1 ........... ....... 7-30 7. 3. 3 Point Design 2........................ 7-30 7.4 Mechanical Design ......... ............... .... 7-32 7. 4. 1 Structural Configuration . .......... 7-32 7. 4. 2 Thermal Effects ..... ................. 7-34 7.4. 3 Telescope Cross-Scan Drive Systems . ....... 7-36 7.4.4 Weight ....... ..... ............... ... 7-39 7. 5 Calibration .............................. 7-46 7. 5. 1 Inflight Radiometric Calibration . ......... 7-46 7. 5. 2 Preflight Calibration .......... .... 7-48 7. 6 Minimum Weight OPM Imager Designs.......... 7-50 8 IMAGE SEQUENCE PLAN FOR JUPITER ORBITER MISSION.. ................... 8-1 8. 1 Introduction to Orbit Geometry ......... 8-1 8.2 Step Rate Selection ........................... ..... 8-7 8.3 Plan for Orbit 1....... ................... 8-9 8. 3. 1 Jupiter Imaging .......................... 8-13 8. 3. 2 Satellite Imaging ........ ............ .. 8-27 8. 4 Overview for Six Orbits and Summary ......... 8-38 9 REFERENCES ................................ 9-1 SANTA BARBARA RESEARCH CENTER vi SBRC ILLUSTRATIONS Figure Page 3-1 MTF for Ideal and X/10 Telescopes with (E = 1/3) and without (E = 0)Obscuration ....................... .. 3-6 3-2 MTF for 0. 1-mr IFOV and X/10 Telescope . 3-7 3-3 Field of View Geometry for Spin-Scan OPM Imager ........ 3-10 3-4 Illustration of Cross-Scan Aliasing ................... 3-11 3-5 Illustration of Along-Scan Aliasing . ................. 3-12 3-6 Geometry with Spacecraft Spin Axis and Trajectory Both in Equatorial Plane of Planet . 3-19 3-7 Rate of Change of Look Angle Versus Height Above Surface for Jupiter Orbit .......................... 3-21 3-8 Rate of Change of Look Angle Versus Height Above Surface for Saturn Flyby .......................... 3-22 3-9 Rate of Change of Look Angle Versus Height Above Surface for Polar Uranus Flyby .................... 3-23 3-10 Geometric Albedos for Outer Planets . 3-25 4-1 Reconstructed ATS-1 Imagery for Scene Area 1 with and without Data Compaction ...................... .. 4-9 4-2 Reconstructed ATS-1 Imagery for Scene Area 2 with and without Data Compaction ...................... 4-10 4-3 Motion of Spacecraft during Hypothetical Image ........... 4-14 4-4 Unrectified Spin-Scan Images of Rotating and Translating Globe .. .. .... .. .. ....... .. 4-15 4-5 Geometric Solution Procedure ..................... 4-18 4-6 Scan Map of Jupiter from Jupiter Orbiter for Conditions Indicated .................................. 4-21 4-7 Example Mapping of IPP Test Data onto Display Plane ...................................... 4-23 4-8 Data of Figure 4-4 Displayed According to Scan Map of Figure 4-7 .............................