TPF-I SWG Report - Exoplanet Exploration Program - NASA

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C HAPTER 6 Table 6-3 Flight Requirements for Formation Flying with the TPF Interferometer Ref Parameter TPF-I Formation Flying Requirements per Operating Mode 1 Operating Envelope Units Safe-Standoff Reconfiguration Hand-off Observation 2 Formation Sensor Acquis. Sensor Acquis. Sensor Med Sensor Fine Sensor 3 Inter-S/C Range m 20–200 20–10,000 20–80 20–80 4 Inter-S/C Bearing – 4π steradians 4π steradians 10° cone 10 arcmin cone 5 Inter-S/C Range Rate 6 Inter-S/C Bearing Rate < cm/s 200 200 5 0.2 < arcmin/s 60 60 10 2.5 7 Acquisition Time < s 5 30 10 10 8 Range 9 Knowledge cm 100 50 1 0.1 10 Control cm 200 200 5 2 11 Range Rate 12 Knowledge cm/s 1 0.1 0.1 0.001 13 Control cm/s 5 0.5 0.5 0.050 14 Bearing 15 Knowledge arcmin 1800 60 1 0.067 16 Control arcmin – 300 5 0.333 17 Bearing Rate 18 Knowledge arcmin/s – 1 0.167 0.0007 19 Control arcmin/s – 5 1.000 0.0100 20 Attitude (Abs. Sensor) 21 Knowledge arcmin 1 1 0.1 0.1 22 Control arcmin 60 60 3.0 1.0 23 Attitude Rate (Abs. Sensor) 24 Knowledge arcsec/s 1 1 1 1 25 Control arcsec/s 5 5 5 5 140
T E C H N O L O G Y R OADMAP FOR TPF-I There are four operating modes that have been defined: safe stand-off, reconfiguration, hand-off, and observation. The precise boundary between the different operating modes is to some extent arbitrary, since it depends on the capability of the sensors that are chosen. The acquisition sensor has the poorest resolution but the widest coverage in range and bearing angle. The acquisition sensor will be used primarily to establish the array configuration, reconfigure it, and recover from faults that would cause elements of the array to lose their station. The fine sensor has the most restricted coverage in bearing angle and is used to maintain the formation during science observations. The medium sensor has a capability allowing hand-off between the acquisition sensor and the fine sensor. It is the delay and delayrate limitations of the interferometer during the science observations that drive the formation-flying requirements. The requirements on formation flying are decoupled as much as possible from the requirements on nulling. The formation-flying system is envisioned as the “coarse stage” of a multi-layer control system that maintains the optical pathlengths. Centimeter-level variations in the relative positions of the spacecraft are sensed by the instrument’s fringe tracking system and compensated for by the optical-delay lines in each beamtrain, each of which is required to provide a control range of ±10 cm of optical delay. The small changes in the relative bearing angles between the spacecraft are compensated by the articulation of steering mirrors on the collector and combiner spacecraft. The thrusters and reaction wheels will be important disturbance sources for the interferometer, but optomechanical modeling will be needed to establish the appropriate requirements. The range and bearing control requirements during science observations are imposed by the limitations of the fringe sensor and delay line of the interferometer. If the fringes are allowed to move beyond the throw of the delay line, they will be lost. Similarly, if the fringes move too quickly for the fringe tracker to sense them, they will also be lost, even if they are within range of the delay line. The limitations of the delay line therefore impose requirements on range and bearing angle, and limitations of the fringe tracker impose requirements on range rate and bearing rate. The optical path-difference is required to be controlled to ±1 cm along the beam path, for both in-plane and out-of-plane directions. This ±1-cm control requirement is shown in Table 6-3, row 10 under the ‘Observation’ operating mode. A bearing requirement of ±0.33 arcmin is equivalent to ±1 cm spacecraft position control at the shortest baseline with the collector spacecraft center-to-center separation of 100 m. Specific requirements are also levied on the ground technology development during the current pre-Phase A efforts. Since the flight conditions can be simulated in a high-fidelity simulation, the Formation Algorithms and Simulation Testbed is identical to the flight requirements listed in Table 6-3. The requirements for the multi-robot based Formation Control Testbed are somewhat relaxed, though scalable to flight requirements, and are given in Table 6-4. 141
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JPL Publication 07-1 Terrestrial Pl
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Abstract Over the past two years, t
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Acknowledgements Twenty-two represe
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Table of Contents 1 Introduction...
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4.8.3 Post-Nulling Calibration.....
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6.4.5 Double Fourier Interferometry
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I NTRODUCTION 1 Introduction Over 2
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I NTRODUCTION et al. 2004), and res
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I NTRODUCTION Standard Interferomet
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I NTRODUCTION 1.4 References Angel,
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C HAPTER 2 0.7 to 1.5 AU scaled by
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C HAPTER 2 Table 2-2. Illustrative
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C HAPTER 2 Classical interferometry
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C HAPTER 2 trivial in the absence o
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C HAPTER 2 Figure 2-3. Simulated mi
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C HAPTER 2 would be in atmospheres
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C HAPTER 2 Figure 2-6. The mid-infr
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C HAPTER 2 Lines of constant stella
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C HAPTER 2 presence of zodiacal clo
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C HAPTER 2 S EZ 2π ∫ θ max ∫
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C HAPTER 2 Figure 2-11. Observation
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C HAPTER 2 Figure 2-12. Models of t
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C HAPTER 2 Beichman, C. A., Fridlun
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C HAPTER 2 2.7.4 Suitable Targets E
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C HAPTER 2 Reach, W. T., Franz, B.
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C HAPTER 3 3.1.1 Darwin/TPF-I Prope
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C HAPTER 3 clouds or an OB associat
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C HAPTER 3 Figure 3-3. Three possib
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C HAPTER 3 the circumstellar disk,
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C HAPTER 3 Figure 3-6. (Left panel)
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C HAPTER 3 Continuum interferometry
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C HAPTER 3 Figure 3-9: Simulated im
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C HAPTER 3 3.3 Conclusions Darwin/T
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C HAPTER 3 Nguyen, H. T., Kallivaya
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D ESIGN AND A R C H I T E C T U R E
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Page 103 and 104: D ESIGN AND A R C H I T E C T U R E
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Page 114 and 115: C HAPTER 5 Heavy launch vehicle. Th
Page 116 and 117: C HAPTER 5 5.3.2 Combiner Spacecraf
Page 118 and 119: C HAPTER 5 5.3.5 Beam Transfer betw
Page 120 and 121: C HAPTER 5 Figure 5-8. Control sche
Page 122 and 123: C HAPTER 5 Figure 5-9. First sectio
Page 124 and 125: C HAPTER 5 Figure 5-9 shows the fir
Page 126 and 127: C HAPTER 5 5.4.4 Shear Metrology Sh
Page 128 and 129: C HAPTER 5 Figure 5-15. TPF-I Fligh
Page 130 and 131: C HAPTER 5 secondary mirror along t
Page 132 and 133: C HAPTER 5 a) c) b) d) IWA = 43 mas
Page 134 and 135: C HAPTER 5 planets found. Figure 5-
Page 136 and 137: C HAPTER 5 30 25 5 M earth 3 M eart
Page 138 and 139: C HAPTER 5 5.8.4 Angular Resolution
Page 140 and 141: C HAPTER 5 Table 5-3. Angular Resol
Page 142 and 143: C HAPTER 5 The optimization works b
Page 145 and 146: T E C H N O L O G Y R OADMAP FOR TP
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Page 177 and 178: F UTURE D EVELOPMENTS Table 7-1. Pr
Page 179 and 180: D ISCUSSION AND C ONCLUSION 8 Discu
Page 181 and 182: Appendices 167
Page 183 and 184: T E C H N O L O G Y A DVISORY C O M
Page 185 and 186: F L I G H T S YSTEM C ONFIGURATION
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Page 190 and 191: A PPENDIX C 2. Identical FACS fligh
Page 192 and 193: A PPENDIX C 2. Recall that the coef
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Page 200 and 201: A PPENDIX C The “true” time of
Page 202 and 203: A PPENDIX C References Cohen, S., a
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A PPENDIX D DC DCB DM DM DOCS DOD D
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A PPENDIX D NaCl NAR NASA NASTRAN N
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A PPENDIX E Appendix E TPF-I Review
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A PPENDIX F Alice Quillen, Universi
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A PPENDIX F Figure 3-1 - Original f
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