The New Worlds Observer: Opening Direct Study of Exo-planets Using External Occulters Webster Cash University of Colorado & The NASA Institute for Advanced Concepts.
Download ReportTranscript The New Worlds Observer: Opening Direct Study of Exo-planets Using External Occulters Webster Cash University of Colorado & The NASA Institute for Advanced Concepts.
The New Worlds Observer: Opening Direct Study of Exo-planets Using External Occulters Webster Cash University of Colorado & The NASA Institute for Advanced Concepts 1 New Worlds Contributors Webster Cash Jim Green Phil Oakley Jeremy Kasdin Bob Vanderbei David Spergel Sara Seager Steve Kilston Charlie Noecker Jon Arenberg Ron Polidan Chuck Lillie Amy Lo Tiffany Glassman Glenn Starkman Sally Heap Marc Kuchner Keith Gendreau Don Lindler Rick Lyon Doug Leviton Aki Roberge Maggie Turnbull Giovanna Tinetti University of Colorado Princeton University MIT Ball Aerospace Northrop Grumman Case Western Goddard Space Flight Center STScI University College London and growing… 2 Exoplanets The Planets That Circle Other Stars There are probably 1000 within 10pc (30 light years) of the Earth. Indirect means have now found over 200. If we can observe them directly, we will have a new field of astronomy every bit as rich as extragalactic. 3 Boy Have We Got A Problem! An Earth-like Planet Is 10 Billion Times Fainter Than Its Parent Star 6pack vs Bill Gates entire fortune AND Less Than 0.1 Arcseconds Away One Hubble Resolution Element Courtesy of N-G 4 Exploration & Science One doesn't discover new lands without consenting to lose sight of the shore for a very long time. Andre Gide (1869 - 1951) Science requires a hypothesis suggesting knowledge of the answer while exploration has no such conceit. New Worlds is Exploration First Science Second 5 Indirect Means Over 200 Exoplanets Now Known Mostly from Radial Velocity Measurements 6 Direct Imaging is What We Want Can We Ever Map Extra-Solar Systems In This Manner? 7 Terrestrial Planet Finder Must be done from space because of the atmosphere Telescopes must be corrected to PERFECTION –to suppress scatter: l/5000 surface, 99.999% reflection uniformity TPF is very difficult NASA has not been good to TPF lately. They are on indefinite hold. 8 TPF-I Terrestrial Planet Finder - Interferometer Works in Mid-Infrared ~25microns 9 TPF-I & Darwin Mid-Infrared Interferometer Multiple Large Cooled-IR Telescopes Combine Beams Null Out Star at One Angle Constructive Interference at Nearby (Planet) Angle 10 TPF-C Terrestrial Planet Finder - Coronagraph Works in Visible Band 11 TPF-C Visible Light Coronagraph Planet light Planet Light Starlight Stop scatter starlight 4x8m Space Telescope 12 External Occulters Let’s Resurrect an Old Idea – Spitzer (1962) appears to be the first Just Keep the Starlight Out of the Telescope 13 Occulter Diagram Planet Target Star NWD Starshade JWST 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 14 New Worlds Observer 15 Fly the Telescope into the Shadow 16 Dropping It In Note: No Outer Working Angle 17 The Obstacle Diffraction Despite What They Tell You in Sixth Grade Light Does Not Move In Straight Lines 18 Occulters Several previous programs have looked at occulters Used simple geometric shapes – Achieved only 10-2 suppression across a broad spectral band With transmissive shades – Achieved only 10-4 suppression despite scatter problem http://umbras.org/ BOSS Starkman (TRW ca 2000) 19 Extinguishing Poisson’s Spot Occulters Have Very Poor Diffraction Performance – The 1818 Prediction of Fresnel led to the famous episode of: – Poisson’s Spot (variously Arago’s Spot) – Occulters Often Concentrate Light! Must satisfy Fresnel Equation, Not Just the Fraunhoffer Equation Must Create a Zone That Is: – Deep – Wide – Broad Below 10-10 diffraction A couple meters minimum Suppress across at least one octave of spectrum Must Be Practical – Binary – Size – Tolerance Non-transmitting to avoid scatter Below 150m Diameter Insensitive to microscopic errors 20 A Solution Exists A 0 for a and A 1 e a b n for a 21 Binary Shape 22 Performance A 50m diameter occulter at 50,000km will reveal Earths at 10pc a=b=12.5m n=6 F=50,000km 23 Huygens-Fresnel Principle E0 ikr E Ae dS il r F s 24 Continue Integrating by Parts Drop Small Terms Dominant Term n! 1 1 R n n 1 n! n n If 2 >> n 25 New Code Still Need Computer Simulations e.g. Some Disagreement about Minimum Number of Petals Direct Fresnel 2-d integral is very slow Princeton, Goddard , NGST, CU All Working on this new cu code – – – – Integrate Fresnel by parts Yields edge integral --- like Green’s Theorem Very Fast Will Allow Diffraction Analysis with Any Error 26 Shadow of 16 Petal Mask Linear Log 27 Simulated Solar System Most of the following simulations are from Phil Oakley 28 Additional Contrast from Telescope 10-8 10-7 10-6 29 The First Image of Solar System Uranus Galaxies Zodiacal Light Jupiter Saturn Neptune 10 arcseconds 30 90 80 70 60 50 40 30 20 10 31 Discoverer Science Simulations Starshade Shadow Jupiter Exo-Zodiacal Jupiter Saturn Mars Earth Saturn 32 Spectroscopic Biomarkers Water Oxygen Ozone Nitrous Oxide Methane Vegetation Necessary for habitability Free oxygen results only from active plant life Results from free oxygen Another gas produced by living organisms Life indicator if oxygen also present Red edge of vegetation at 750nm 33 Spectroscopy R > 100 spectroscopy will distinguish terrestrial atmospheres from Jovian with modeling H2O O2 CH4 NH3 S. Seager 34 1 3 2 4 Venus (bright spot) and Earth (dimmer spot) inclinations: 0,30,60,90 35 Just Earth (left). Earth from Voyager (right) 36 Brightness Profiles 0.5 0.95 37 Photometry of the Earth 38 A Year of Watching the Earth Simulated Photometric Data Including Instrument Effects and Statistics 39 Best Inversion for a cloudless planet 40 Best case inversion for a cloudy Earth (requires 50mas IWA and reduced noise system) 41 Is This Lifefinder? What is the definition of Lifefinder? Scientifically: Be able to understand chemistry of atmosphere and surface? Operationally: Spectroscopy at R~1000? 42 Implementation No pessimist ever discovered the secret of the stars or sailed an uncharted land, or opened a new doorway for the human spirit. Helen Keller (1880 - 1968) 43 Tall Poles Deployment of 35m shade to mm class tolerance Acquiring and holding line of sight Fuel usage, orbits and number of targets Stray Light – particularly solar 44 Lab Studies 45 Starshade Tolerances Position Lateral Distance Several Meters Many Kilometers Angle Rotational Pitch/Yaw None Many Degrees Shape Truncation Scale Blob 1mm 10% 3cm2 or greater Holes Single Hole Pinholes 3cm2 3cm2 total 46 Alignment acquisition & hold 47 L2 Orbit Favorable 48 Planning the Mission 49 Status of New Worlds NIAC Complete Concept Study Proposal Decadal Review – Does General Astrophysics Too 50 NWO Science Result of Nature interviews Many discussions with press and other interested parties It is Life Seeking that EVERYBODY wants Just finding water planets enough, but its not what motivates the public Can there be a bigger or more important question for astronomers? New Worlds Observer can do it $2-3 Billion and 10 years 51 Conclusion By 2025 By 2013 H2O O2 There is nothing in the above mission that the people in this room could not implement today. Money for such a mission will be available in two years. This is an obvious candidate. 52