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Darwin and the Origins of Extrasolar Species

Darwin and the Origins of Extrasolar Species. Rene´ Liseau Stockholm Observatory Delegate to the Scientific Advisory Teams of ESA : TE-SAT

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Darwin and the Origins of Extrasolar Species

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  1. rene@astro.su.se

  2. Darwin and the Origins of Extrasolar Species Rene´ Liseau Stockholm Observatory Delegate to the Scientific Advisory Teams of ESA : TE-SAT NASA : TPFI-SWG http://www.astro.su.se/groups/infrared/index.html rene@astro.su.se

  3. Outline Astronomical Jargon, Definitions & Acronyms Extrasolar Planets (known) Extrasolar Planets (expected) Detection Techniques (known possibilities) Detection Techniques (selected: ESA – Darwin, NASA–TPFI) Optical Architecture (destructive interference, formation flying) Mission Characteristics (payload, launcher, orbit selection) The Future (future missions) rene@astro.su.se

  4. Astronomical Jargon : shall attempt to avoid Sorry, if too trivial... rene@astro.su.se

  5. Definitions & Acronyms 1 pc 1 AU 1´´ rene@astro.su.se

  6. Definitions & Acronyms Seeing limited 1´´ 8m diffraction limited rene@astro.su.se

  7. Definitions & Acronyms rene@astro.su.se

  8. Goals of Darwin: + Find other Earths and Find X-solar Life rene@astro.su.se

  9. What is Known: Discovery of Extra-solar Planets since 1995 update : 26 November 2005 Global statistics :   146 planetary systems   170 planets   18 multiple planet systems rene@astro.su.se

  10. Earth Uranus Neptune Jupiter Saturn Sun Exo-Planet Type rene@astro.su.se

  11. mass = 0.003 radius = 0.1 density = 5 mass = 1000 radius = 10 density = 1 mass = 1 radius = 1 density = 1 rene@astro.su.se

  12. Distribution of KNOWN Exoplanets BIASED by METHOD of OBSERVATION rene@astro.su.se

  13. Observation of STELLAR REFLEX MOTION (Doppler) orbit << 0.001 RSun P = 1 yr Earth: 30 km s-1 Sun: < 10 cm s-1 O ( 100 RSun ) rene@astro.su.se

  14. Observation of STELLAR REFLEX MOTION P = 1 yr Earth: 30 km s-1 Sun: 9 10-5 km s-1 12 yrJupiter: O ( m s-1 ) 5.2 AU Distance Not Yet Sensitivity DV ~ 10 m s-1 rene@astro.su.se

  15. Besides Vrad , other known observational methods planetary transits radius and density of occulting planet micro-lensing statistics of remote systems distance of O (10 kpc) direct imaging of structure in young disks presence of planet(s) rene@astro.su.se

  16. Besides Vrad , other known observational methods pulsar timing planet´s mass first detection of Earth-mass planets... rene@astro.su.se

  17. known observational methods useful for exo-Earths ? radial velocities N stellar activity of O (m s-1) stellar astrometry Y from space O (marcsec) planetary transits Y from space ( DI/I < 10- 4 ) micro-lensing Y O (hour) , not repetitive imaging of disk structure N O (MJup) , not unique pulsar timing Y few systems, no Life rene@astro.su.se

  18. known observational methods useful for exo-Earths ? radial velocities N stellar activity of O (m s-1) stellar astrometry Y from space O (marcsec) planetary transits Y from space ( DI/I ~ 10-4 ) micro-lensing Y O ( hour) , not repetitive imaging of disk structure N O (MJup) , not unique pulsar timing Y few systems, no Life Life rene@astro.su.se

  19. What is ? How originated ? Life rene@astro.su.se

  20. Definition of Life... ? (1). Organisms tend to be complex and highly organized. Chemicals found within their bodies are synthesized through metabolic processes into structures that have defined purposes. Cells and their various organelles are examples of such structures. Cells are also the basic functioning unit of life. Cells are often organized into organs to create higher levels of complexity and function. (2). Living things have the ability to take energy from their environment and change it from one form to another. This energy is usually used to facilitate their growth and reproduction. We call the process that allows for this facilitation metabolism. (3). Organisms tend to be homeostatic. In other words, they regulate their bodies and other internal structures to certain normal parameters. (4). Living creatures respond to stimuli. Cues in their environment cause them to react through behavior, metabolism, and physiological change. (5). Living things reproduce themselves by making copies of themselves. Reproduction can either be sexual or asexual. Sexual reproduction involves the fusing of haploid genetic material from two individuals. This process creates populations with much greater genetic diversity. (6). Organisms tend to grow and develop. Growth involves the conversion of consumed materials into biomass, new individuals, and waste. (7). Life adapts and evolves in step with external changes in the environment through mutation and natural selection. This process acts over relatively long periods of time. ... etc ... rene@astro.su.se

  21. Origin of Life ? rene@astro.su.se

  22. What does Life DO ? ! Generates WASTE ! rene@astro.su.se

  23. Life transforms a planet - e.g. its Atmosphere oxygen methane Time (Ga) rene@astro.su.se

  24. Cyano Bacteria `bluegreen algae´ produce sugar and OXYGEN oxygenic photosynthesis: 2H2O + CO2 + hn CH2O + O2 + H2O rene@astro.su.se

  25. Chemical Disequilibrium Atmosphere : simultaneously reducing .and. oxydizing WATER .and. CARBON DIOXIDE .and. OXYGEN 2H2O+ CO2 + hn CH2O + O2 + H2O rene@astro.su.se

  26. IMPLIES BIOACTIVITY rene@astro.su.se

  27. IMPLIES BIOACTIVITY • Spectrum • in • Thermal Infrared • Earth is Hot • Atmospheric Lines Opaque • Needs Space rene@astro.su.se

  28. PROBLEM OF CONTRAST Scattered Solar Radiation 1O10 versus 107 Planetary Thermal Emission log10 Visible InfraRed rene@astro.su.se

  29. PROBLEM OF CONTRAST 1 10-11 to 10-7 of central peak intensity in the wings of the PSF ... and in real life not inifinite signal-to-noise PSF = Point Spread Function = Fourier Transform of Modular Transfer Function (MTF) rene@astro.su.se

  30. Solution: Darwin the Mission Nulling Interferometer Destructive Interference provides Needed Contrast Long Baselines provide Needed Resolution rene@astro.su.se

  31. Nulling Interferometer: Point Sources simplest case: 2 element Bracewell interferometer to``null´´ stellar radiation [e.g. at 10 pc distanceand l= 10 mm] Sun 1.6 Jy* (N= 3.6 mag ) Earth0.23 mJy (N= 20.7 mag) = star on optical axis * 1 Jy = 10-26 W m-2 Hz-1 q = 0 Rejection Rate: qn> 105 n = 2 for Bracewell rene@astro.su.se

  32. This is wonderful ! So - does everything come for free ? We gain resolution but loose information and field But for POINT SOURCES OK! rene@astro.su.se

  33. D Filled aperture D: contains all spatial frequencies up to 1/D => Image of the source rene@astro.su.se

  34. D B d/2 Interferometer B: picks out 1 spatial frequency 1/B in coherent field of view 1/d Example: l = 10 mm, B = 200 m, d = 2 m Resolution = 10 milliarcsec Field of view = 1 arcsec rene@astro.su.se

  35. Equilateral triangle - Darwin architecture: 3.5 m • BCS in the centre of triangle • 120 deg between telescopes • Variable distance TS to BCS rene@astro.su.se

  36. Modulation properties rene@astro.su.se

  37. Spectroscopy rene@astro.su.se

  38. Beam Combination by Single Mode Waveguide Single mode waveguide (SMW) used for modal filtering to improve nulling ratio.Phase relations in SMW of injected on-axis light such that resulting amplitude is zero.Internal modulation by alternating phase shifts between (-120º, 0º, +120º) and(+120º, 0º, -120º) A B C φA(t) φB(t) φC(t) Focusing Optics Stellar light can not propagate in fibre core and is rejected into the cladding Single Mode Waveguide Detector Ref. O. Wallner et. al “Multi-axial single mode beam combiner” rene@astro.su.se

  39. Beam Combination rene@astro.su.se

  40. Signal-to-Noise (S/N) Local zodi Thermal BG Exo zodi (10) Detector Total noise Leakage Transmitted planet signal Equivalent signal of absorption lines SNR integrated over line width rene@astro.su.se

  41. Science Requirements rene@astro.su.se

  42. Science Requirements, cntd. rene@astro.su.se

  43. Assumptions rene@astro.su.se

  44. Main Observational Requirements • Nulling of “on axis” star by 105 • Baseline accuracy 1 cm • Optical Path Difference (OPD) 20 nm • Telescope pointing 24 mas • Amplitude matching 10- 2 rene@astro.su.se

  45. Control Modes Baseline Control Mode Pointing: 1 arcsec Baseline accuracy = 1 cm Array attitude: 0.1 deg. Fringe Acquisition Mode Optical Links acquisition Freeze of baselines External OPD rate damping Fringes Acquired Normal Operation Mode OPD control to 20 nm Pointing control 24 mas New target / baselinere-arrangement Flyers randomly distributed in a sphere (15 km) rene@astro.su.se

  46. Baseline Control Mode • mN-FEEP • Inertial attitude using star-trackers [ ~1” ] • RF range measurement [ 1 cm ] • RF goniometry • omni-directional [10 deg ] • narrow angle scanning antennae [ 0.06 deg ] rene@astro.su.se

  47. Propulsion • Fine control: mN - thrust • Coarse control: mN - thrust • FEEP - Field Emission Electric Propulsion • Cold gas rene@astro.su.se

  48. Micro propulsion rene@astro.su.se

  49. Preliminary Mission Analysis Mission analysis initiated with ESOC. rene@astro.su.se

  50. IRSI - Darwin Nuller at L2 rene@astro.su.se

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