The Wide Field Infrared Survey Telescope (WFIRST)

1. The Wide Field Infrared Survey Telescope (WFIRST) James Green and Paul Schechter Co-Chairs of the Science Definition Team Neil Gehrels: Project study scientist Kevin Grady: Project study managerRita Sambruna: Program scientistLia LaPiana: Program executive Space Telescope Science Institute June 13, 2011

2. The SDT 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.”

3. The SDT Charter “In particular, the SDT report should present assessments about how best to proceed with the WFIRST mission, covering the cases that the Euclid mission, in its current or modified form, proceeds to flight development, or that ESA does not choose Euclid in the near future.”

4. WFIRST Science Objectives(equally weighted – still subject to word smithing) 1: Complete a statisticalcensus of planetary systems in the Galaxy, from habitable Earth-mass planets to free floating planets, including analogs to all of the planets in our Solar System except Mercury. 2: Determine the expansion history of the Universe and its growth of structure so as to test explanations of its acceleration such as Dark Energy and possible modifications to Einstein's gravity. 3: Produce a deep map of the sky at NIR wavelengths, enabling new and fundamental discoveries ranging from mapping the Galactic plane to probing the reionization epoch by identifying thousands of quasars at z>10.

5. Key Conclusions of the SDT 1: WFIRST should include all of the science objectives and utilize all of the techniques outlined in the decade recommendation: A: Baryon Acoustic Oscillation Survey B: Exo-Planet Microlensing Survey C: Supernova Ia survey D: Weak Lensing Survey E: Infrared Sky Survey – including a survey of the galactic plane F: Guest Observer Program G: Redshift Space Distortion Survey (Free)

6. Key Conclusions of the SDT 2: Due to the importance of the scientific questions, and the need for verification of the results, WFIRST should proceed with all of its observational capabilities intactregardless of the ESA decision on EUCLID. The actual observation program might be altered in light of EUCLID’s selection or in response to any EUCLID results prior to WFIRST’s launch.

7. Key Conclusions of the SDT 3: Should NASA and ESA decide to pursue a joint mission, all of the capabilities currently included in WFIRST must be included in the joint mission.

8. WFIRST Design Reference Mission (DRM)* used in the  interim report  Off – Axis Three Mirror Anastigmat Design with field pickoffs to tailor the plate scale for imaging and spectroscopy Supernova spectroscopy performed through insertion of prism as a “filter” in the imaging channel * The DRM is a straw man mission concept to demonstrate the capabilities of WFIRST for purposes of the interim report. The final mission parameters and observational implementation will only be finalized after further study.

10. DRM Observational Capabilities Dark Energy: BAO/RSD : 11,000 deg2/dedicated year Weak Lensing: 2700 deg2/dedicated year SN Ia Survey: 100 SN per z= 0.1 bin /dedicated 6 months

11. DRM Microlensing Capabilities • Detection to 0.1 Mearth • Detect > 90 planets of MEarth (in 2 year orbits) per dedicated observing year • Observe  2 square degrees in the Galactic Bulge at ≤ 15 minute sampling cadence • Minimum continuous monitoring time span: ~60 days • Separation of ≥4 years between first and last observing seasons

12. DRM Observational Capabilities NIR Survey: High Latitude data collected in imaging channel during BAO survey Galactic Plane Survey a dedicated observational plan Exact parameters still TBD

13. DRM Observational Plan Actual assigned times to each survey still in flux. Mission lifetime is 5 years.

14. Preliminary Mechanical Design Telescope Back Enclosure Telescope Tube Spectrometer A Spectrometer B Telescope Bottom Enclosure 7.5 meters Telescope Primary Structure Spacecraft Bus Imager SDT#5 Telescope

15. Imager Optical Layout Secondary Mirror Primary Mirror Field Stop at Cassegrain Focus Tertiary Mirror Imager Focal Plane F2 F1 Cold Stop and F3 SDT#5 Telescope

16. Imager Optics Secondary Mirror Primary Mirror Field Stop at Cassegrain Focus Tertiary Mirror Imager Focal Plane F2 F1 F3 Cold Stop SDT#5 Telescope

17. Spectrometer A & B Layout Secondary Mirror Spectrometer Focal Planes Tertiary Mirror Cold Stop F3 Primary Mirror Field Stop at Cassegrain Focus F1 F2 SDT#5 Telescope

18. Spectrometer Optics Secondary Mirror Spectrometer Focal Planes Tertiary Mirror Cold Stop F3 Primary Mirror Field Stop at Cassegrain Focus F2 F1 SDT#5 Telescope

19. Possible Modifications Under Further Study • Extend coverage further to the red (current bandpass cuts off at 2.0 m • Add an IFU spectrometer for SN Ia work (instead of inserted prism) • Add additional filters • Increase the field of regard to simplify operations • Extend operational lifetime

20. Conclusions • WFIRST will be an exciting, powerful, and versatile observatory that will perform the surveys needed to advance our understanding of planetary systems, cosmology, fundamental physics, and astronomy. • It addresses the most pressing questions in astronomy that can be addressed with the technologies available today. • It needs the full support of the community to move forward.

21. Sub-committee Membership(external members in italics) Exoplanet Microlensing: Dave Bennett, Bob Brown, Scott Gaudi, Takahira Sumi, Angelle Tanner, Jay Anderson, Eamonn Kerins, Jonathan Lunine High Latitude Survey: (Baryon acoustic oscillation, Infrared survey and weak lensing): Rachel Bean, Chuck Bennett, Chris Conselice, Jason Rhodes, Tom Roellig, Yun Wang, Ned Wright, Chris Hirata and Zeljko Ivezic Supernovae as a probe of the expansion history: Charlie Baltay, Tod Lauer, Bob Nichol, Saul Perlmutter, Peter Garnavich, Mark Phillips, Adam Riess Galactic Plane survey and Guest Observer program: Megan Donahue, Daniel Stern, Kem Cook, Roeland van der Marel, George Rieke, Lynne Hillenbrand