Department of Energy: SPS Brightness Due to Reflected Sunlight

Cover	1
Title Page	3
Table of Contents	5
1.0 Summary	9
2.0 Statement of Problem	11
2.1 Background	11
2.2 Scope of Investigation	13
3.0 Research and Analysis	15
3.1 Reflectance of Vehicles	15
3.1.1 Reflection Analysis	15
3.1.2 Structure Characteristics	17
3.1.2.1 Description of Spacecraft Elements	19
3.1.2.2 Reflection Qualities of Materials	41
3.1.3 Ground Illumination	49
3.1.3.1 Geometrical Considerations	49
3.1.3.2 Irradiance Levels	51
3.2 Sky Brightness	64
4.0 Conclusions and Recommendations	72
4.1 Conclusions	72
4.2 Recommendations	75
5.0 References	77
Appendix A: Computer Cod for Vector Rotations	78
Appendix B: Radiant Quantities and Units	79
List of Figures	6
Figure 1. Typical Reflection Configuration for the Solar Power Satellite at GEO	12
Figure 2. The Ground Irradiance Due to Specular Reflection of Sunlight	18
Figure 3. Spectral Reflectance Unit Vector Definition	20
Figure 4. LEO Staging Base Configuration	20
Figure 5. LEO Staging Base With OTV Structure	21
Figure 6. LEO Staging Base Coordinate System	22
Figure 7. Orbit Transfer Vehicle Configuration	28
Figure 8. Orbit Transfer Vehicle Structural Details	28
Figure 9. Orbit Transfer Vehicle Structure Perspec	29
Figure 10. Orbit Transfer Vehicle Coordinate System	30
Figure 11. Solar Power Satellite Configuration	34
Figure 12. Solar Power Satellite Subelement Structure	35
Figure 13. Solar Power Satellite Coordinate System	36
Figure 14. Directional Reflectance Characteristics of Magnesium Oxide	42
Figure 15. Directional Reflectance Characteristics of Magnesium Oxide	42
Figure 16. Analyzed Normal Spectral Reflectance of Smoked Magnesium Oxide	43
Figure 17. Spectral Reflectance of Z-93 Paint	44
Figure 18. Spectral Reflectance of Aluminum	46
Figure 19. Spectral Reflectance of Carbon Graphite	47
Figure 20. Relative Reflective Intensity Distribution From Various Spacecraft Materials	48
Figure 21. Specular Reflectance Unit Vector Definition	50
Figure 22. Diffuse Reflection From SB in LEO During OTV Construction (D1)	53
Figure 23. Diffuse Reflection From SPS in GEO (D2)	55
Figure 24. Diffuse Reflection From OTV During Transit from LEO (D3)	55
Figure 25. Specular Reflection From SB and OTV During Construction Phase (S1)	58
Figure 26. Angular Dependence of OTV-Earth Distance and Irradiance	59
Figure 27. Specular Reflection From SPS Solar Panels In GEO Around Equinoxes (S2)	62
Figure 28. Specular Reflection From SPS Antenna in GEO Around Equinoxes (S3)	62
Figure 29. Specular Reflection From OTV in LEO During Uncontrolled Maneuvers	65
Figure 30. Specular Reflection From SPS Solar Panels in GEO During Uncontrolled Maneuvers	65
Figure 31. Sky Brightness Geometric Coordinate Relationships	67
List of Tables	7
Table 1. LEO Staging Base Element Descriptions	23
Table 2. Orbit Transfer Vehicle Element Description	31
Table 3. Solar Power. Satel 1 ite Element Descriptions	37
Table 4. Theoretical Sky Brightness and Polarization at 10,000 Foot Altitude in Clear Air	69
Table 5. Summary of Ground Irradiance	73

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