TPF-C Technology Plan - Exoplanet Exploration Program - NASA

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Chapter 4 Figure 4-8. Comparison of passive isolation performance versus DFP performance for line-ofsight stability requirement. outputs. In this analysis, two reaction wheels were assumed to spin at the same speed with random phasing, the structural damping ratio was assumed to be 0.1%, and model uncertainty factors were also added to increase conservatism. Figure 4-8 illustrates the LOS performance for the passive isolation design (red line) and DFP (blue line), as well as the requirement (green line). The passive isolation design cannot alter the system response for frequencies below the isolator break frequency, typically ~2 Hz, but can achieve 40–60 dB attenuation per stage at frequencies sufficiently above the break frequency. Although the passive isolation design does not meet the LOS requirement at low wheel speeds, it is simple to limit wheel speeds to above 2 Hz where passive isolation can meet the requirement with a large margin. The DFP, on the other hand, does not have a theoretical limit in rejecting vibrations at low frequencies. As a result, the active DFP design can meet the LOS requirement for all wheel speeds and demonstrate vibration reduction about two orders of magnitude better than the passive isolation design. The wavefront error (WFE) due to telescope deformation, expressed in terms of the first 15 Zernike amplitudes, is plotted in Figure 4-9. The top graph shows the margin in dB for each Zernike amplitude: ⎛ max Z i ( ω) ⎞ − 20 log ⎜ ⎟, i = 4...15 ⎝ Ri ⎠ where Z i is the amplitude of Zernike mode i versus wheelspeed, and R i is the requirement for mode i. The bottom graph shows the peak Zernike amplitude from the passive isolation and DFP designs as blue and green lines, respectively, along with the requirement for each mode in 66
Structural, Thermal, and Spacecraft <strong>Technology</strong> nanometers shown in red. The insets show the deformation pattern for each of the Zernikes. The legend indicates the frequency at which the peak response occurs. For this analysis, the passive isolation design is sufficient to satisfy all Zernike amplitude requirements, and the DFP performance exhibits between 1 and 2 orders of magnitude margin on all requirements. The upto-date analysis shows that a three-stage passive isolation design is sufficient to meet requirements with wheel speed limitation or damping augmentation. The active DFP design seems to demonstrate even greater vibration reduction capabilities but carries additional risks as mentioned above. margin [dB] 30 20 10 0 4 5 6 7 8 9 10 11 12 13 14 15 3L/D Requirement Zernike Reponse with MUF [nm] 10 -3 10 -4 10 -5 10 -6 10 -7 10 -2 Zernike Mode DFP: peak response all frequencies 3-stage passive: peak response >10.0 Hz 10 -8 4 6 8 10 12 14 16 Figure 4-9. WFE due to telescope deformation for 3-stage passive isolation (blue) and for DFP pointing/isolation system with conservative assumptions on cable stiffness and residual coupling (green): top graph, dB margin for each Zernike mode; bottom graph, peak Zernike amplitude from 10-100 RPS wheelspeed plotted along with the requirement. 67
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JPL Publication 05-8 Technology Pla
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TECHNOLOGY PLAN TERRESTRIAL PLANET
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Recent Highlights Technical progres
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Figure i-4. Deformable mirror deliv
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Table of Contents Approvals........
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7.5.2 Precision Hexapod............
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Chapter 1 Figure 1-1. Artist's impr
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Chapter 1 interferometry, continues
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Chapter 1 Back end coronagraph opti
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Chapter 1 Surrounding the whole tel
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Chapter 1 Pol. BS fold/steering Mic
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Chapter 1 1.6.5 Sunshield The teles
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Chapter 1 expected architecture dow
Page 28 and 29: Chapter 1 Table 1-3. TPF-C Technolo
Page 30 and 31: Chapter 1 3B: Demonstrate, using th
Page 32 and 33: Chapter 2 2 Error Budgets 2.1 Contr
Page 34 and 35: Chapter 2 Error Budget Validation G
Page 36 and 37: Chapter 2 Further, it is shown that
Page 38 and 39: Chapter 2 Table 2-1. Requirement on
Page 40 and 41: Chapter 3 3 Optics and Starlight Su
Page 42 and 43: Chapter 3 are in progress with cont
Page 44 and 45: Chapter 3 Figure 3-5. Coronagraph s
Page 46 and 47: Chapter 3 (though not light-weight
Page 48 and 49: Chapter 3 Table 3-3. ITT Metrology
Page 50 and 51: Chapter 3 observations. The time it
Page 52 and 53: Chapter 3 vacuum-compatible, low-po
Page 54 and 55: Chapter 3 blank size. Westerhoff et
Page 56 and 57: Chapter 3 configurations, performan
Page 58 and 59: Chapter 3 Figure 3-10: Plots showin
Page 60 and 61: Chapter 3 The wavefront quality of
Page 62 and 63: Chapter 3 Figure 3-13. Optical layo
Page 64 and 65: Chapter 3 algorithms have limitatio
Page 66 and 67: Chapter 3 simulated star source is
Page 68 and 69: Chapter 4 Figure 4-1. Overview of t
Page 70 and 71: Chapter 4 enclosures, and stable la
Page 72 and 73: Chapter 4 facilities from which dat
Page 74 and 75: Chapter 4 Figure 4-5. Microslip Tri
Page 76 and 77: Chapter 4 Figure 4-7. Calibration o
Page 80 and 81: Chapter 4 4.2 Subsystem and System
Page 82 and 83: Chapter 4 Figure 4-11. Schematic of
Page 84 and 85: Chapter 4 Figure 4-12. Fine guiding
Page 86 and 87: Chapter 4 (5) The Fine Steering Mir
Page 88 and 89: Chapter 4 Third, precise thermal co
Page 90 and 91: Chapter 4 giving confidence that fl
Page 92 and 93: Chapter 4 surface polish is nonethe
Page 94 and 95: Chapter 5 TPF-C is planning a suite
Page 96 and 97: Chapter 5 engineering judgment (i.e
Page 98 and 99: Chapter 5 categories, in reality ea
Page 100 and 101: Chapter 5 Table 5-3. Validation of
Page 102 and 103: Chapter 5 5.6.1 Modeling Methodolog
Page 104 and 105: Chapter 5 strength of computer simu
Page 106 and 107: Chapter 6 6 Instrument Technology a
Page 108 and 109: Chapter 6 Figure 6-1. Detailed conc
Page 110 and 111: Chapter 6 The first method is self-
Page 112 and 113: Chapter 6 super computers and is us
Page 114 and 115: Chapter 7 7 Plan for Technology Dev
Page 116 and 117: Chapter 7 Figure 7-1. TPF-C Technol
Page 118 and 119: Chapter 7 Improvements to the DM ov
Page 120 and 121: Chapter 7 7.3 Error Budgets 7.3.1 D
Page 122 and 123: Chapter 7 7.4 Optics and Starlight
Page 124 and 125: Chapter 7 7.4.2 Apodizing Masks and
Page 126 and 127: Chapter 7 7.4.4 Wavefront Sensing a
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Chapter 7 7.4.6 Transmissive Optics
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Chapter 7 7.4.8 Scatterometer Scope
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Chapter 7 7.5 Structural, Thermal,
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Chapter 7 7.5.3 Precision Structura
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Chapter 7 model of TPF-C and should
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Chapter 7 7.5.6 Secondary Mirror To
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Chapter 7 7.5.8 Sub-scale EM Sunshi
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Chapter 7 7.6 Integrated Modeling a
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Chapter 7 7.7.3 Advanced Concepts:
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Chapter 8 134
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Appendices Appendix B: TPF-C Detail
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Appendices Appendix D: TPF-C Techno
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Appendices Appendix F: Acronym List
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Appendices RWA SAO SBIR SIM SM SMFA
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TPF-C Technology Plan - Exoplanet Exploration Program - NASA

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