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UMBRAS

UMBRAS. Distant Screens: From Extrasolar Planets to Eclipsing the North Star. Ian J. E. Jordan, December 6, 2005 Space Telescope Science Institute. http://umbras.org. http://westminsterastro.org. Mark Kochte, Dorothy Fraquelli, F. Hamilton, Charlie Wu. Ian Jordan

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UMBRAS

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  1. UMBRAS Distant Screens: From Extrasolar Planets to Eclipsing the North Star Ian J. E. Jordan, December 6, 2005 Space Telescope Science Institute http://umbras.org http://westminsterastro.org

  2. Mark Kochte, Dorothy Fraquelli, F. Hamilton, Charlie Wu. Ian Jordan • Computer Sciences Corporation @ STScI UMBRAS Core Investigators • Helen M. Hart • Applied Physics Lab • Paul Henze, George Sauter, Erich Bender, Brian Eney, Ron Smith • Westminster Astronomical Society, Inc. • Alfred B. Schultz, Richard Lyon, Peter Chen, Jan M. Hollis, Ken Carpenter, Jesse Leitner, Richard Burns, Scott Starin • NASA/Goddard • Fred Bruhweiler • CUA/IACS • Bryce Roberts • U.C. Berkeley • Dennis Skelton • Orbital Sciences Coproration • Ed Rowles • Blue Horizons • Glenn D. Starkman, Craig G. Copi • Case Western Reserve Univ. • Zolt Levay • AURA

  3. An Outline for this Evening… • Introduction: Extrasolar planets--to date. • History & Workings of External Occulters • Ground Demonstration w/ WASI participation.

  4. Successful Planet Finding Techniques Direct Imaging & Coronography Transit Candidates found: ~3 Microlensing Candidates found: ~2-50 Courtesy L. Cook, exoplanets.org Candidates found: ~2 Candidates found: ~130 Pulsar Timing Candidates found: ~4 Courtesy: Penn State & Alex Wolszczan

  5. Extrasolar Planet Count: 156, and growing!

  6. 2M1207 & GQ Lupi Ground-based & HST surveys are starting to yield direct images of planets, but these are very far away from their parent stars, very large, and/or very young.

  7. TPF: What is the problem? TPF: Terrestrial Planet Finder … Detect & study earth-like planets around nearby stars. • Earth < 0.” 1 from the sun when viewed from 33-light years away • (diameter of a quarter at 50 km). • Sol appears 10-billion (1010) times brighter than earth. Occulter: “covering up” the star improves star-planet contrast. Before After

  8. COSMOS Carl Sagan in COSMOS Episode 7 “The Backbone of Night.”

  9. A Brief History of Occulters <1962 Robert Danielson, Princeton Infinite Half-plane analysis 1962 Lyman Spitzer, Princeton American Scientist “Beginnings & Future…” 1972 Su-Shu Huang, Northwestern Resurrected Spitzer’s analysis 1974 Gordon Woodcock, Boeing Occulter Vehicle Design 1978 Hugh S. Hudson, UCSD, et.al. Shuttle-borne Pinhole Occulter Facility 1978 James Elliot, Cornell Lunar occultation for LST, Hill Orbits 1980 Carl Sagan COSMOS "Backbone of Night" episode 1985 Christian Marchal, ONERA Spergel-Kasdin-like Screen Shapes 1995 Jean Schneider, Obs. de Paris SCODOTEP 1997 G. Starkman, C. Copi, CWRU IRIS (opaque occulter) 1998 G. Starkman, C. Copi, CWRU BOSS (apodizing occulter) 1998 Schultz, Jordan, Hart, et.al. UMBRAS (feasability studies) 2001 R. Lyon, A. Schultz, et.al. Occulter + Shaped Aperture /Apodization 2005 W. Cash, et.al. New Worlds Observer (Marchal occulter)

  10. Woodcock Occulter ~ 60-m diameter deployable “umbrella” packaged in a 2.5-m x 10-m upper stage.

  11. BOSS Variable Transmission Screen Occulter • What is BOSS? -- It is a different kind of occulter mission. • BOSS employs an apodizing occulter without using multiple PSF suppression stages within the telescope. Plot & Image courtesy of BOSS team, TRW, & JPL

  12. Bus closeup

  13. Tri-aspect Component Diagram

  14. Constellation Configuration in Space

  15. Operations Cycle

  16. TPF-C+O

  17. Telescope-Occulter Control Block Diagram • Telescope science imager takes picture(s) • Pictures are measured to determine occulter position • Error signal transmitted to occulter • Occulter adjusts position & velocity

  18. Sunward view of UMBRAS Occulter

  19. Launching Multiple Occulters

  20. Transit Time: Function of Separations

  21. Ambient Earth-Sun L2 Accelerations NSTAR acceleration level Differential Acceleration Magnitude (m/s2) Science Ceiling Earth-Sun L2.20,000 km Telescope-Occulter separation, with non-sail-like telescope & occulter properties for a likely typical TPF mission. • Brown solid = D-gravitational (earth) • Black dotted = D-gravitational (sun) • Green solid = ~D solar radiation pressure • Yellow solid = D-gravitational (moon) • Blue dashed = max allowed gas leakage (10%) • Orange dotted = ~ nominal D solar wind Sun-Telescope-Occulter Angle (degrees)

  22. Why an Occulter? Point Spread Function Slices using a 4-metre Telescope ASA: WFQ = l/1000 ASA + O: WFQ = l/100 Better suppression of the stellar PSF wings even with lower wavefront quality. ASA = Apodized Square Aperture WFQ = Wave Front Quality

  23. Dawes’ Limit 8-m V-band Dawes’ Limit 2.4-m V-band Discovery Space Diagram Exoearths fainter than mV=32 not plotted. B6V A5V Exoearth mV=29.5 G0V K3V M1V M3V Alpha Cen A M4V Alpha Cen B Tau Ceti M7V Epsilon Eridani Pi3 Orion Epsilon Indi TPF-C goal. TPF-C goal + minimal Occulter.

  24. Occulter vs Alternate Method Cost FL = Fresnel Lens FFO = Free-Flying Occulter NIFF = Free-Flying Nulling Interferometer NIM = Monolithic Nulling Interferometer LAC = Large Aperture Coronagraph ULSA = Ultra-Large Sparse Aperture SIM = Space Interferometry Mission

  25. The New Worlds Observer/Imager Concept

  26. Ground ‘Tests’ of Occulters W=occulter width; z=separation; l=wavelength; D=aperture. D=4m; z=20,000 km D=9mm;z=100m

  27. Ground Test Equipment • Hand-crafted (P. Henze) occulter-rig. • 12-inch diameter light shroud tube. • Square-rail optical bench. • Mid-tube occulter placement slot. • 1- and 2-inch square occulters. • 9” 1/10th-wave flat & mirror cell (GSFC). • Alt-az mirror mount. • Red laser for optical alignment. • F/5 Televue 101-mm refractor. • Masked down to 11 & 24 mm. • Optional Barlow: system f/# from 50 - 100. • Mounted atop 8” + alt/az for stability. • ST-7X, TEC-cooled, 768x512 CCD camera. • M675X laptop data acquisition/storage. • Green laser for optical alignment.

  28. Pic 15

  29. Pic 11

  30. Pic 27

  31. Pic 25

  32. Pic 3

  33. Pic 6

  34. Pic 4

  35. Experiment Field of View. 9” mirror 25-mm (~ 15 pixels) edge occulter August 7/8, 2004 626-second drift. 765 x 510 9-m pixels, 540-mm focal length, distance ~ 95 metres

  36. Occultation Movie Watch for real diffraction lobes!

  37. Movie C 19:45 November 5, 2004, Drift 6, 24-mm aperture.

  38. Theory & Experiment: Comparison Admittedly, this is red and green apples, but . . . . Unapodization • Polychromatic Dl/l ~ 0.5, • Circular aperture, • Atmospheric induced wavefront error, • Atmospheric smearing Sonine 4 Apodization • Monochromatic, • Square aperture, • No wavefront error

  39. UMBRAS/WASI Occulter Demonstration Team October 31, 2004

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