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 manager Rita Sambruna: Program scientist Lia LaPiana: Program executive Space Telescope Science Institute June 13, 2011

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.”

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.”

WFIRST Science Objectives (equally weighted – still subject to word smithing) 1: Complete a statistical census 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.

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)

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 intact regardless 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.

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.

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.

DRM Observational Capabilities Dark Energy: BAO/RSD : 11,000 deg 2 /dedicated year Weak Lensing: 2700 deg 2 /dedicated year SN Ia Survey: 100 SN per  z= 0.1 bin /dedicated 6 months

DRM Microlensing Capabilities Detection to 0.1 M earth Detect > 90 planets of M Earth (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

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

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

Preliminary Mechanical Design Spacecraft Bus Telescope Tube Telescope Primary Structure Spectrometer B Spectrometer A Telescope Bottom Enclosure Imager Telescope Back Enclosure 6/8/1114SDT#5 Telescope 7.5 meters

Imager Optical Layout Primary Mirror Secondary Mirror Field Stop at Cassegrain Focus F1 F2 Tertiary Mirror Imager Focal Plane Cold Stop and F3 6/8/1115SDT#5 Telescope

Imager Optics Primary Mirror Secondary Mirror Field Stop at Cassegrain Focus F1 F2 Tertiary Mirror Imager Focal Plane Cold Stop F3 6/8/1116SDT#5 Telescope

Spectrometer A & B Layout Primary Mirror Secondary Mirror Field Stop at Cassegrain Focus F3 F2 Tertiary Mirror Spectrometer Focal Planes Cold Stop F1 6/8/1117SDT#5 Telescope

Spectrometer Optics Primary Mirror Secondary Mirror Field Stop at Cassegrain Focus F3 F2 Tertiary Mirror Spectrometer Focal Planes Cold Stop F1 6/8/1118SDT#5 Telescope

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

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.

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