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WFIRST SDT and Project Studies

Explore the WFIRST space mission's objectives, technology, and key conclusions from SDT studies. Learn about the science requirements and configurations for the telescope.

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WFIRST SDT and Project Studies

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  1. WFIRST SDT and Project Studies Neil Gehrels WFIRST Study Scientist Princeton Workshop September 4, 2012

  2. WFIRST Summary • WFIRST is the highest ranked large space mission in NWNH, and plans to: • - complete the statistical census of Galactic planetary systems using microlensing • - determine the nature of the dark energy that is driving the current accelerating expansion of the universe • - survey the NIR sky for the community • - conduct a guest observer program • Measurements all require wide-field NIR observatory • - NIR sky surveys for BAO and weak lensing and • - NIR monitoring for SNe and exoplanets • Space-qualified large format HgCdTe detectors • are US developed technology and flight ready H4RG Mosaic Plate H2RG EDU FPA

  3. WFIRST Dark Energy Systematics Control for SNe Bright Ha line for BAO Atek+ '12 Kowalski+ '08 Galaxy Shapes in IR for WL Kocevsk+ '11

  4. WFIRST Exoplanets Kepler WFIRST Figures from B. MacIntosh of the ExoPlanet Task Force

  5. WFIRST NIR Surveys NIR Imaging Surveys NIR Redshift Surveys WFIRST WFIRST-SN WFIRST WFIRST provides a factor of 100 improvement in IR surveys

  6. Key Conclusions of the SDT WFIRST Happenings • WFIRST created by NWNH EOS panel from JDEM (dark energy), MPF (exoplanetmicrolensing) and NIRSS (IR surveys) (JDEM Omega configuration, 1.5m telescope) • Science Definition Team (SDT) formed November 2010 Co-Chairs Jim Green & Paul Schechter • SDT interim report June 2011 (arXiv 1108.1374) (IDRM – off-axis telescope version of JDEM-Omega) • Discussion of using NRO telescope with 2.4m mirror • SDT final report August 2012 (DRM1 & DRM2 – off-axis telescopes, single instrument)

  7. The SDT Charter SDT original Charter “The SDT is to provide science requirements, investigation approaches, key mission parameters, and any other scientific studies needed to support the definition of an optimized space mission concept satisfying the goals of the WFIRST mission as outlined by the Astro2010 Decadal Survey.” 2nd Year - Complete detailed study of primary configuration - Create a second cheaper option that is complementary to Euclid, LSST and JWST - Augment SDT with 5 new members

  8. WFIRST Science Definition Team Paul Schechter, MIT Co-Chair James Green, U. Colorado/CASA Co-Chair Rachel Bean, Cornell University Charles Baltay, Yale David Bennett, Univ. of Notre Dame Robert Brown, STScI Christopher Conselice, Univ. of Nottingham Megan Donahue, Michigan State Univ. Scott Gaudi, Ohio State Univ. Tod Lauer, NOAO Bob Nichol, Univ. of Portsmouth Saul Perlmutter, UC Berkeley / LBNL Bernard Rauscher, GSFC Jason Rhodes, JPL Thomas Roellig, Ames Daniel Stern, JPL Takahashi Sumi, Nagoya Univ. Angelle Tanner, Mississippi State Univ. Yun Wang, Univ. of Oklahoma Edward Wright, UCLA Neil Gehrels, GSFC Ex-Officio Wes Traub, JPL Ex-Officio Rita Sambruna, NASA HQ Ex-Officio New Members Jan. 2012 Nikhil Padmanabhan, Yale David Weinberg, Ohio State U. Xiaohui Fan, U. Arizona Chris Hirata, Caltech Jason Kalirai, STScI

  9. H4RG-10 Mosaic Plate with WFIRST Science Definition Team, NASA HQ, and Project Office Team February 3, 2012

  10. Requirements Flowdown • Substantiation that WFIRST can achieve NWNH science • Traces science requirements from top level objectives

  11. Over 80 Concepts Developed

  12. TMA Telescope • Three Mirror Anastigmatic • Unobscured (unocculted) design • Three powered (curved) mirrors • 9 degrees of freedom from mirrors • (curvature, conic constant, position for each) • Allows control of 9 parameters • (focal length, magnification of each mirror, astigmatism, coma, spherical aberration, field curvature) • Wider field than Ritchey-Chrétien • Better image quality than Schmidt

  13. NIR Detectors • H2RG detectors • H >> HAWAII = HgCdTe Astron. Wide Area IR Imager • 2 >> 2048 x 2048 pixels • R >> reference rows & columns to correct bias fluctuations • G >> guiding function, selectable window for guide star • Space H1Rs used on HST. • Space H2RGs developed for JWST • Goals of WFIRST program • Larger mosaics than JWST • Silicon carbide support structure • H4RG development Sensor Chip Assembly GSFC SI Carbide mount

  14. Design Reference Missions • IDRM • 1.3 meter off-axis telescope • 3-channel payload • 5 year mission • Atlas V Launch Vehicle • DRM1 • 1.3 meter off-axis telescope • Single channel payload • 5 year mission • Atlas V Launch Vehicle • DRM2 • 1.1 meter off-axis telescope • Single channel payload • 3 year mission • Falcon 9 Launch Vehicle

  15. Design Reference Missions • IDRM • 1.3 meter off-axis telescope • 3-channel payload • 5 year mission • Atlas V Launch Vehicle • DRM1 • 1.3 meter off-axis telescope • Single channel payload • 5 year mission • Atlas V Launch Vehicle • DRM2 • 1.1 meter off-axis telescope • Single channel payload • 3 year mission • Falcon 9 Launch Vehicle

  16. WFIRST DRM1Payload Optics Block Diagram Telescope Instrument • 180 mas/pix ~205K Unobstructed, Focal Telescope: 9x4 FPA; 2kx2k.18 μm SCAs; 150 Mpix; 100K; 0.6-2.4µm bandpass; 0.375 deg2 Active Area ColdPupil Mask Filter Wheel PrismWheel PM and SM followed by Tertiary Mirror (TM) and fold flats that feed the science channel and an auxiliary FGS TM 180 mas/pix f/15.9 8 positions (6 filters, open, blank) 6 positions (3 prism assemblies, {SN, 2 GRS}, 3 open) “Outrigger FGS” SCAs (4, in pink) shown in notional positions on Focal Plane Science Channel 1.3 m Aperture SN Resolving power 75/2pixel; GRS Dispersion DQ= 160-240 arcsec 1x2 FPA; 2kx2k, 18μm pixel size SCAs; ~8 Mpix; <120K; 0.6-2.0µ bandpass; 0.04 deg2Active Area 250 mas/pix; f/11.4 Auxiliary FGS 0.30° x 0.14° FOV Extent GRS = Galaxy Redshift Survey FGS = Fine Guidance Sensor: Outrigger FGS used during imaging, Auxiliary FGS used during spectroscopy SN = Type1a Supernovae

  17. DRM1 Field of view & focal plane layout H2RG detectors • WFIRST-JWST Focal plane Comparison • Area is 145x larger than NIRCAM (0.375 vs. 0.00259 sq degrees • Focal plane has 5x more pixels than NIRCAM short wave cameras (150 vs 33 Mpix)

  18. CANDELS fields on DRM1 focal plane from J. Kruk

  19. DRM2 Field of view & focal plane layout H4RG detectors • WFIRST-JWST Focal plane Comparison • Area is 226x larger than NIRCAM (0.585 sqvs 0.00259 degrees) • Focal plane has 7x more pixels than NIRCAM short wave cameras (235 vs 33 Mpix)

  20. WFIRST DRM1 Observatory Layout & Ray Trace GRS prism FPA F2 F1 SM radiator Spacecraft PM TM Solar array/sunshield

  21. WFIRST DRM2 Observatory Layout • Sun at bottom • WMAP-like progression from warm solar array (300K) to cold focal plane (100K) from bottom to top • Overall dry mass 500+ kg less than DRM1 Radiator FPA Solar array(blue) & sunshade Launch configuration Instrument Telescope Spacecraft Solar array(blue) & sunshade, deployed

  22. Survey Strategies GPS HL Survey WL & BAO Example DRM1 Observing Plan GO Program Sun angle (deg) SNe exoplanets Time (months) from C. Hirata

  23. DRM1 Performance • Exoplanets: • >2000 bound exoplanets of 0.1 – 10,000 Earth mass (MEarth) • >30 free floating planets of 1 MEarth •  200 terrestrial planets* (0.3 – 3 MEarth) • Accelerating Universe: • WL and BAO surveys of >1400 deg2 per year to a Hα line spectroscopy • limit of 1 × 10−16 ergs/cm2/sec and imaging limit of AB=26. • SNe-Ia: 2 tiered survey covering 6 deg2 and 2 deg2 with a five day • cadence over 1.8 years yielding ~100 SNe per ∆z = 0.1 bin • NIR Surveys: •  2000 quasars at redshiftz> 7 and  35 quasars at redshift > 10 • Broad-band NIR spectral energy distributions of  3 X 109 galaxies • Map of Galaxy structure using red giant clump stars as tracers

  24. WFIRST DRM1 Schedule Estimate • 79 month development schedule • Start of Phase B FY 15 • Launch Readiness Date Sept ember 2020 • 7 month schedule reserve Funded Schedule Reserve

  25. Cost Estimates • The WFIRST Independent Cost Estimate by Astro2010 (based on JDEM configuration) was $1.6B • The Project Office cost estimates indicate that DRM1 would have a full cost less that $1.6B due to single instrument channel and reduced mass. • The Independent Cost Estimate for DRM2 is $1.1B

  26. Conclusions • The SDT and Project have completed the action of developing two compelling mission concepts. • DRM1: Fully responsive to the objectives of NWNH at reduced cost • DRM2: Capable low-cost near-infrared survey opportunity. The limited 3 year life precludes full compliance with NWNH goals. • Path forward: • Study WFIRST mission utilizing NRO telescope with new SDT • Develop 4kx4k IR detectors for wide-field applications

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