National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds Exoplanet Science with Ares-V Enabled Telescopes Wesley A. Traub Jet Propulsion Laboratory, California Institute of Technology Astrophysics 2020: Large Space Missions Beyond the Next Decade Space Telescope Science Institute November 2007

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 2Traub Big Questions Are there Earth-like planets around nearby stars? Are there signs of life on these planets? SIM TPF-C/O TPF-I

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 3Traub Earth is 10 billion/million times fainter than Sun visible infrared

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 4Traub Planets found so far (HUGE ones!) Planets we hope to find (Earth-size!)

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 5Traub Spectra If we can image a planet, we can measure its spectrum, characterize its surface, and search for life.

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 6Traub Molecular column MassIR fluxIR colorVis flux Vis & IR spectra Eff temp. RadiusAlbedo Greenhouse warming Density of planet Surface gravity Surface & cloud reflectances Surface pressure Scale height of atmos. Lapse rate of atmos. Surface Temp. TPF-C TPF-C & TPF-ITPF-I SIM measured derived Type of planet Likelihood of plate tectonics & atmos retention Presence of H 2 O Cumulus, cirrus, ice, rock, sand, water implied Habitability of an Earth-like Planet

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 7Traub Visible spectra Near-IR spectra Infrared spectra Vegetation variation TPF-CTPF-ITPF-C derived implied Water, oxygen, carbon dioxide variations Cloud variation Surface spectrum variation Temperature variations Mass of atmosphere observed Orbital eccentricity Cloud height variations Large-scale weather patterns Obliquity Thermal time const of atmos Continents, oceans, ice areas SeasonsLength of day SIM Variability On An Earth-like Planet

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 8Traub Blue (  m), Green (  m), Red (  m) Color Gives a First Impression of a Planet Solar system planets have colors that label them by type. Planet spectra

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 9Traub Earth Spectra Thermal infrared Visible

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 10Traub Visible Earthshine Spectrum Observed Earthshine, reflected from dark side of moon. Woolf, Smith, Traub, & Jucks, ApJ 574, p.430, 2002 Rayleigh Ozone O 3 Chlorophyll 720 nm edge Oxygen O 2 Water H 2 O Marked features show habitability & signs of life

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 11Traub Near-IR Earthshine Spectrum Ref.: Turnbull et al., ApJ, June 2006 Integrated- Earth spectrum Individual gas species All features show habitability & signs of life: H 2 O, O 2, CO 2, CH 4, cirrus, cumulus

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 12Traub Far-infrared spectrum of Earth: validation Integrated light of Earth, seen by TES enroute to Mars. CO 2, O 3, H 2 O dominate. CH 4, N 2 O ~hidden by 6-micron water. H2O CO2 O3 H2O T T T

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 13Traub Terrestrial Planet Finder Coronagraph (TPF-C) Candidate space mission in coming decade (2010s) Goal: Image Earth-like exoplanets and measure their visible spectra

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 14Traub Lab demo, with planets added Trauger & Traub, Nature, April 2007 D Jupiter Earth ½ Jupiter 500 D-shaped images of dark hole, Rotated to sample annulus on sky, Planets added, Common speckles removed, Planets pop out of noise. Shows that Earth could have been detected.

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 15Traub Terrestrial Planet Finder Interferometer (TPF-I) Candidate space mission in following decade (2020s) Goal: Image Earth-like exoplanets and measure their infrared spectra

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 16Traub TPF-Interferometer 1. star, planet, & zodi, seen as a single (not resolved) blob by each telescope 2. four collector telescopes & one combiner, plus delay lines, all free-flying 3. transmission pattern, times sky image, seen as a single blob; total amount of light received is noted 4. array rotates 5. measured total light level, as array rotates a full turn (bumps are the planet) Single wavelength

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 17Traub TPF-I and Ares V Speculations needing further study: Individual TPF-I collectors do not want to be larger, because diffraction pattern will cut off outer planets. But more collectors in array could help a lot, giving advantage of closure phase to imaging process.

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 18Traub Terrestrial Planet Finder Occulter (TPF-O) Candidate space mission in coming decade (2010s) Goal: Image Earth-like exoplanets and measure their visible spectra

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 19Traub Occulters Telescope big enough to collect enough light from planet Occulter big enough to block star –Want low transmission on axis and high transmission off axis Telescope far enough back to have a properly small IWA No outer working angle: View entire system at once NWD Starshade JWST Target Star Planet

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 20Traub Kaltenegger et al 2005 in prep. Early…present Earth spectra O3O3 O2O2 CH 4 CO 2 Oxygen appears in atmosphere Oxygen-producing bacteria start Methanogens start First life consumes CO 2 High CO 2 compensates for faint Sun Earth Over Geologic Time Refs: Kasting, Scientific American; Kaltenegger et al, 2006; Holland 2006 Vis. spectrum

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 21Traub Signal, Noise, and Time If every star has an Earth-like planet in its habitable zone, how many targets could we see, how well could we characterize each planet, how large a telescope would we need, and how long would it take?

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 22Traub Number of HZs vs Telescope Diameter HZ center (mas) 2 m 56 stars 4 m 460 stars 8 m 3100 stars 16 m 18,000 stars Database: Assumes IWA = 2 /D, & planet in center of HZ

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 23Traub Earth spectrum

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 24Traub Earth & Zodi Model * Assume Earth = Sun. Then the Earth signal per day, at V, in 10% band, in A  = 2, is S = (227 elec.)[(D/D 0 )/(x/x 0 )] 2 (e/e 0 )(t/t 0 )/(R/R 0 ) * Assume zodi = 21.5 mag/arcsec 2 (STDT,  =10 -7, local+exozodi). Then the noise per day, at V, in 10% band, (sqrt of zodi) is N = (89 elec.)[(e/e 0 )(t/t 0 )(z/z 0 )/(R/R 0 )] 1/2 Here D 0 = 1 m telescope diameter x 0 = 10 pcdistance to star e 0 = 0.5electrons/photon (efficiency) t 0 = 1 dayintegration time R 0 = 10 /  (spectral resolution) z 0 = 1 local + 1 exo zodi (total zodi toward star)

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 25Traub Integration time The SNR is Earth signal / zodi noise, which gives integration time: t = (0.16 day) (S/N) 2 [(x/x 0 )/(D/D 0 )] 4 (R/R 0 )(z/z 0 )/(e/e 0 ) for both V and I wavelength regions. If we want S/N = 5, and use R=R 0, z=z 0, e=e 0, we get t = (4.0 day) [(x/x 0 )/(D/D 0 )] 4 where x 0 = 10 pc and D 0 = 1 m, as before.

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 26Traub Number of stars & integration times (10% resol.) From the NStED database, for all stars with a mid-HZ greater than IWA = 2 /D, where here use = 1 micron. Diameter# starsdistance time per star time per star time per star closemidfarclosemidfar m563 pc22 pc160 pc0.003 d5.9 dyrs 4 m4603 pc37 pc390 pc d 2.9 dyrs 8 m31003 pc62 pc500 pc~0 d1.4 dyrs 16 m pc89 pc340 pc~0 d0.4 dmonths

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 27Traub Spectral Feature Detection A spectral feature has depth d with respect to the continuum, where 0<d<1. It has width , and resolution R = / . The integration time to detect this feature, with a given S/N, is t(feature) = t(continuum)  R / d 2

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 28Traub Earth Spectra through Geologic Time Kaltenegger & Traub, 2007 Age = 1.0 Gyr Age = 4.5 Gyr Age = 2.5 Gyr

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 29Traub Earth-like Spectral Feature Detection Times (days) D tel x pc Rayleigh 0.45  m H 2 O 1.13  m H 2 O 0.94  m O  m O  m CH  m CH  m H 2 O 0.82  m 2 m10 pc m20 pc m30 pc m40 pc all ages present Earth early Earth Assume targets are at middle of nearest half of each sample, so representative of about 30, 200, 1500, and 8000 stars, respectively.

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 30Traub TPF-C and Ares V Speculations needing further study: A large (e.g., 8-16 m) off-axis primary mirror will provide enormous gains (~D 4 ) in TPF-C exoplanet science. A segmented mirror generates diffraction spikes which will dominate any exoplanet signal, so should be minimized or avoided entirely.

National Aeronautics and Space Administration Jet Propulsion Laboratory California Institute of Technology Navigator Program Exploring New Worlds 31Traub Thank you !