TPF-I SWG Report - Exoplanet Exploration Program - NASA

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C HAPTER 2 Figure 2-6. The mid-infrared spectral features on an Earth-like planet change considerably over its evolution from a CO 2 -rich (epoch 0) to a CO 2 /CH 4 -rich atmosphere (epoch 3) to a present-day atmosphere (epoch 5). The black lines show a spectral resolution of 25 comparable to the proposed TPF-I mission concept designs. (Kaltenegger et al. 2006) This would indicate a stronger feature at 6.3 µm. However, this feature is so strong that it is relatively insensitive to atmospheric water abundance. Models of Earth’s atmosphere indicate that in the extreme clear-sky case, that the depth of this feature is very similar for water column abundances between 10% and more than 200% of the Earth’s present water abundance. 1 Methane and nitrous oxide have features nearly overlapping in the 7-μm region, and additionally both lie in the red wing of the 6.3-μm water band. The 6.3-μm H 2 O feature could act instead as a “true/false” indicator of the presence of even very small amounts of water if the atmosphere is an Earth-analog. Additionally the photons emission is very low at 6.3 μm (see section 2.2).The broad rotational band, extending between 12 and 200 μm, has little spectral structure. That makes it difficult to discriminate its absorption from other factors affecting the planetary spectrum, such as the temperature of the emitting layer, which could also result in reduced flux in this 1 Victoria Meadows (Caltech), private communication. 22
E X O P L A N E T S CIENCE wavelength region. The instrument design has to take the noise levels at both wavelength ends into account as well as the photons emitted from the planet. Preliminary studies indicate that it will be equally difficult to detect the water line at both features. To conclude this issue, considerable more detailed study is needed. 2.4.5 Biomarkers and Their Evolution over Geological Timescales Terrestrial planets found around other stars may be observed at different stages in their geological and biological evolution. Earth's atmosphere has experienced dramatic evolution over 4.5 billion years, and other planets may exhibit similar or greater evolution, and at different rates. Studies (see e.g., Des Marais et al. 2002; Schindler and Kasting 2000; Kasting and Catling 2003; Selsis, 2000; Pavlov 2000; Traub and Jucks 2002; Segura et al. 2003; Kaltenegger et al. 2007; Meadows 2006) are designed to guide the interpretation of an observed spectrum of such a planet by future instruments that will characterize exoplanets. Figure 2-6 shows theoretical mid-infrared spectra of the Earth at six epochs during its geological evolution (Kaltenegger et al. 2007). The epochs are chosen to represent major developmental stages of the Earth and life on Earth. If an extrasolar planet is found with a corresponding spectrum, we will have good evidence for characterizing its evolutionary state, its habitability, and the degree to which it shows signs of life. The oxygen and ozone absorption features could have been used to indicate the presence of biological activity on Earth anytime during the past 50% of the age of the Solar System. The dark lines show a resolution of 25 in the IR, as proposed for the Darwin/TPF-I mission. 2.5 Suitable Targets Due to angular resolution and sensitivity constraints, the most suitable target stars around which TPF-I can search for exoplanets are the stars nearest the Sun. However, the nearest stars encompass a large variety of stellar types, classes, ages, and multiplicities (as well as distances); and so the set of all nearby stars needs to be trimmed or culled, for both scientific reasons and engineering/observational constraints. The current scientific source selection criteria, defined at a workshop held at the Naval Research Observatory in Washington, DC, in Nov. 2004, are summarized in this section. 2.5.1 Science Criteria The identification of candidate scientific targets for TPF-I should begin with a complete list of nearby stars. The master list selected is the Hipparcos catalogue (ESA 1997) of nearby stars, out to a distance cutoff of 30 pc. This list does not include every star within 30 pc because dim stars at the larger distances do not fall within the Hipparcos sensitivity limit, implying that the list grows less and less complete as stellar temperatures decrease. However, for the primary targets of interest, “solar-like” F, G, and K stars, the list should be fairly complete. 23
Page 1 and 2: JPL Publication 07-1 Terrestrial Pl
Page 3: Abstract Over the past two years, t
Page 7 and 8: Acknowledgements Twenty-two represe
Page 9 and 10: Table of Contents 1 Introduction...
Page 11 and 12: 4.8.3 Post-Nulling Calibration.....
Page 13 and 14: 6.4.5 Double Fourier Interferometry
Page 15 and 16: I NTRODUCTION 1 Introduction Over 2
Page 17 and 18: I NTRODUCTION et al. 2004), and res
Page 19 and 20: I NTRODUCTION Standard Interferomet
Page 21: I NTRODUCTION 1.4 References Angel,
Page 24 and 25: C HAPTER 2 0.7 to 1.5 AU scaled by
Page 26 and 27: C HAPTER 2 Table 2-2. Illustrative
Page 28 and 29: C HAPTER 2 Classical interferometry
Page 30 and 31: C HAPTER 2 trivial in the absence o
Page 32 and 33: C HAPTER 2 Figure 2-3. Simulated mi
Page 34 and 35: C HAPTER 2 would be in atmospheres
Page 38 and 39: C HAPTER 2 Lines of constant stella
Page 40 and 41: C HAPTER 2 presence of zodiacal clo
Page 42 and 43: C HAPTER 2 S EZ 2π ∫ θ max ∫
Page 44 and 45: C HAPTER 2 Figure 2-11. Observation
Page 46 and 47: C HAPTER 2 Figure 2-12. Models of t
Page 48 and 49: C HAPTER 2 Beichman, C. A., Fridlun
Page 50 and 51: C HAPTER 2 2.7.4 Suitable Targets E
Page 52 and 53: C HAPTER 2 Reach, W. T., Franz, B.
Page 54 and 55: C HAPTER 3 3.1.1 Darwin/TPF-I Prope
Page 56 and 57: C HAPTER 3 clouds or an OB associat
Page 58 and 59: C HAPTER 3 Figure 3-3. Three possib
Page 60 and 61: C HAPTER 3 the circumstellar disk,
Page 62 and 63: C HAPTER 3 Figure 3-6. (Left panel)
Page 64 and 65: C HAPTER 3 Continuum interferometry
Page 66 and 67: C HAPTER 3 Figure 3-9: Simulated im
Page 68 and 69: C HAPTER 3 3.3 Conclusions Darwin/T
Page 70 and 71: C HAPTER 3 Nguyen, H. T., Kallivaya
Page 73 and 74: D ESIGN AND A R C H I T E C T U R E
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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
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C HAPTER 5 5.3.2 Combiner Spacecraf
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C HAPTER 5 5.3.5 Beam Transfer betw
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C HAPTER 5 Figure 5-8. Control sche
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C HAPTER 5 Figure 5-9. First sectio
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C HAPTER 5 Figure 5-9 shows the fir
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C HAPTER 5 5.4.4 Shear Metrology Sh
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C HAPTER 5 Figure 5-15. TPF-I Fligh
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C HAPTER 5 secondary mirror along t
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C HAPTER 5 a) c) b) d) IWA = 43 mas
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C HAPTER 5 planets found. Figure 5-
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C HAPTER 5 30 25 5 M earth 3 M eart
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C HAPTER 5 5.8.4 Angular Resolution
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C HAPTER 5 Table 5-3. Angular Resol
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C HAPTER 5 The optimization works b
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T E C H N O L O G Y R OADMAP FOR TP
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F UTURE D EVELOPMENTS 7 Preparatory
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F UTURE D EVELOPMENTS • To comple
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F UTURE D EVELOPMENTS Table 7-1. Pr
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D ISCUSSION AND C ONCLUSION 8 Discu
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Appendices 167
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T E C H N O L O G Y A DVISORY C O M
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F L I G H T S YSTEM C ONFIGURATION
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F L I G H T S YSTEM C ONFIGURATION
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A PPENDIX C 2. Identical FACS fligh
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A PPENDIX C 2. Recall that the coef
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A PPENDIX C Once the formation has
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A PPENDIX C Figure C-3. Example of
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A PPENDIX C Figure C-4. FAST Flight
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A PPENDIX C The “true” time of
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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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TPF-I SWG Report - Exoplanet Exploration Program - NASA

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