TPF-I SWG Report - Exoplanet Exploration Program - NASA

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C HAPTER 6 TPF-I is designed with the capability of arranging the telescope array into a non-redundant geometry, then an alternate beam combiner could be used that maximized the Fourier coverage and, thus, the imaging capabilities. There are possibilities for giving TPF-I truly wide-field imaging capabilities, extending beyond a single primary beam. Wide-field imaging is best obtained using homothetic pupil mapping (Beckers 1986), which is difficult to implement in practice for a reconfigurable array geometry, although formation flying offers a possible context for application. An FOV intermediate between a single primary beam but smaller than the optical vignetting limits can be attained through pupil densification, so-called hyper-telescope concept (Labeyrie et al. 2000, 2003) Novel optical arrangements have also been proposed that, when combined with special OPD modulation schemes, promise to provide a wide-field imaging capability simultaneous with high spectral resolution (e.g., the SPECS concept; Leisawitz et al. 2000). Recently, these schemes have been partially validated in the laboratory, clearly offering attractive features, and further research in this area should be pursued (Rinehart et al. 2006). 6.4.5 Double Fourier Interferometry The mid-IR is rich in spectral features from source components in the solid state and gas phase. The spectrum includes atomic hydrogen recombination lines, ionized neon (Ne), argon (Ar), and sulfur (S) forbidden lines, H 2 rotational lines, and silicate, SiC and polycyclic aromatic hydrocarbon (PAH) features. These features appear on a continuum of thermal-dust emission. A wealth of information is available from the mid-IR spectrum, such as the radiation field intensity and hardness, the dust temperature, and the chemical state of the medium. Kinematic information is potentially available as well, but only when the available spectral resolution is ~10 4 for galaxies or ~10 5-6 for protostars and objects of similar size. The spectral resolution of TPF-I can be increased by increasing the stroke of the delay line. R = 1000 at 10 μm requires only a 1-cm stroke, but R = 10 6 requires a 10-m delay-line stroke, a packaging challenge. Such very high resolutions probably require the addition of a grating. The wide field-of-view double Fourier technique (e.g., Mariotti and Ridgway 1988) can enable a TPF mid-IR interferometer to provide high spatial resolution, high spectral resolution observations of spatially extended astrophysical sources. TPF-I could map protostars, debris disks, extragalactic star-forming regions, and protogalaxies on relevant spatial scales and simultaneously provide the spectroscopic data that would enable deep insight into the physical conditions in these objects. table 6-5 below shows desired measurement capabilities for a variety of targets and indicates that 10 mas is an interesting angular resolution and that ~1 arcmin is an interesting FOV for a wide variety of applications. 152
T E C H N O L O G Y R OADMAP FOR TPF-I Table 6-5. Desired Measurement Capabilities for Desired Targets Ancillary Science Target Protostar (envelope, disk, outflow) Interesting Physical Scales Typical Distance Interesting Angular Scales (arcsec) Desired Resolution 1 – 10 4 AU 140 pc 0.007 70 Desired FOV Debris disk 1 – 300 AU 3.2 pc (e Eri) 0.3 93 30 pc 0.03 10 Extragalactic Giant H II Region Coma cluster galaxy High-z protogalaxy 1 – 100 pc 5 Mpc 0.04 4 0.01 - 10 kpc 107 Mpc 0.02 19 1/100th source to separation between merging systems N/A 0.01 4 The idea behind the double Fourier technique is that a Michelson stellar interferometer equipped with a pupil-plane beamcombiner and a scanning optical delay line can be operated like a Fourier transform spectrometer (FTS). Instead of providing only a visibility measurement for the interferometer baseline established by the collecting aperture locations, such a device produces an interferogram whose 1-D Fourier transform is the spectrum of the target scene on the spatial scales to which the interferometer is sensitive. Combined, the interferograms from all the baselines provide a three-dimensional data cube where the cube has two spatial and one spectral dimension, like the data from the integral field units discussed above. Using a conventional double-Fourier system, a TPF interferometer with 4-m diameter collectors operating at λ = 10 μm with a maximum baseline of 300 m could image a 0.6-arcsec diameter FOV at 4.8-mas spatial resolution. This field of view would be inadequate for the science programs mentioned above. However, the Wide-field Imaging Interferometry Testbed (WIIT) at NASA’s Goddard Space Flight Center was designed to develop and demonstrate a technique for wide-field (i.e., FOV >> 1.2λ/D) imaging in which a detector array is used to enhance the spatial multiplexing efficiency (Leisawitz et al. 2003). In this design, light from field angles θ >> 1.2λ/D relative to the principal axis of the interferometer focuses onto additional pixels in a detector array, which records interferograms shifted by a geometric delay corresponding to |b| times the sine of the component of θ aligned with the baseline vector b. The field of view accessible to an interferometer like WIIT is given by θ FOV = N pix θ p /2, where θ p = 1.2λ/D is the primary beam diameter, N pix is the number of pixels along one dimension of the detector array, and the factor 2 allows for Nyquist sampling of the primary beam. For a 256 2 pixel array 153
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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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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 173 and 174: F UTURE D EVELOPMENTS 7 Preparatory
Page 175 and 176: F UTURE D EVELOPMENTS • To comple
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
Page 187: F L I G H T S YSTEM C ONFIGURATION
Page 190 and 191: A PPENDIX C 2. Identical FACS fligh
Page 192 and 193: A PPENDIX C 2. Recall that the coef
Page 194 and 195: A PPENDIX C Once the formation has
Page 196 and 197: A PPENDIX C Figure C-3. Example of
Page 198 and 199: A PPENDIX C Figure C-4. FAST Flight
Page 200 and 201: A PPENDIX C The “true” time of
Page 202 and 203: A PPENDIX C References Cohen, S., a
Page 204 and 205: A PPENDIX D DC DCB DM DM DOCS DOD D
Page 206 and 207: A PPENDIX D NaCl NAR NASA NASTRAN N
Page 208 and 209: A PPENDIX E Appendix E TPF-I Review
Page 210 and 211: A PPENDIX F Alice Quillen, Universi
Page 212: A PPENDIX F Figure 3-1 - Original f
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TPF-I SWG Report - Exoplanet Exploration Program - NASA

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