Goddard
Space Flight Center
WFIRST - Wide-Field Infra-Red Survey Telescope

About WFIRST

AFTA WFIRST Observatory Concept
WFIRST AFTA Observatory Concept

The Wide-Field Infrared Survey Telescope (WFIRST) is a NASA mission responding to the 2010 National Research Council New Worlds, New Horizons (NWNH) Astronomy and Astrophysics Decadal Survey top priority recommendation in the large space mission category. WFIRST includes science objectives in exoplanet exploration, dark energy research and galactic and extragalactic surveys .

WFIRST was originally configured with a telescope mirror size of 1.3 to 1.5 meters. That changed in 2012 when NASA acquired two telescopes with 2.4 meter primary mirrors from the National Reconnaissance Office (NRO), the same size as the Hubble Space Telescope mirror. In 2013, one of the telescopes was the baselined for WFIRST, generating excitement in the US Astronomical community for Hubble-quality imaging over an area of sky 100 times larger than Hubble. This version of the mission is called WFIRST-AFTA for "Astrophysics Focused Telescope Assets".

NASA has formed 2 different science definition teams (SDTs) to study WFIRST since the 2010 NWNH recommendation. The first one studied versions of the mission with a 1.3 meter off-axis telescope (DRM1) and a less expensive 1.1 meter off-axis telescope (DRM2). The current SDT is studying the WFIRST-AFTA version with the 2.4 meter telescope.

The NWNH report noted that, "WFIRST will settle fundamental questions about the nature of dark energy, the discovery of which was one of the greatest achievements of U.S. telescopes in recent years. It will employ three distinct techniques - measurements of weak gravitational lensing, supernova distances, and baryon acoustic oscillations - to determine the effect of dark energy on the evolution of the Universe. An equally important outcome will be to open up a new frontier of exoplanet studies by monitoring a large sample of stars in the central bulge of the Milky Way for changes in brightness due to microlensing by intervening solar systems. This census, combined with that made by the Kepler mission, will determine how common Earth-like planets are over a wide range of orbital parameters. It will also, in guest observer mode, survey our galaxy and other nearby galaxies to answer key questions about their formation and structure, and the data it obtains will provide fundamental constraints on how galaxies grow ... WFIRST-AFTA addresses fundamental and pressing scientific questions and will contribute to a broad range of astrophysics. It complements the committee's proposed ground-based program in two key science areas: dark energy science and the study of exoplanets."

Science Areas NWNH Key Science Questions
Frontiers of Knowledge
  • Why is the universe accelerating?
  • What is dark matter?
  • What are the properties of neutrinos?
Cosmic Order: Exoplanets
  • How diverse are planetary systems?
  • Do habitable worlds exist around other stars, and can we identify the telltale signs of life on an exoplanet?
  • How do circumstellar disks evolve and form planetary systems?
Understanding our Origins
  • How did the universe begin?
  • What were the first objects to light up the universe, and when did they do it?
  • How do cosmic structures form and evolve?
  • What are the connections between dark and luminous matter?
  • What is the fossil record of galaxy assembly from the first stars to the present?
Cosmic Order: Stars + Galaxies
  • What controls the mass-energy-chemical cycles within galaxies?
  • How do the lives of massive stars end?
  • What are the progenitors of Type Ia supernovae and how do they explode?
WFIRST-AFTA addresses many of the key science questions posed in the NWNH Decadal Survey
M31 Survey
The wide field imaging capability of
WFIRST-AFTA enables large area surveys
at a much faster rate but at the same resolution
as HST/WFC3/IR. The HST/WFC3/IR PHAT
Survey required 432 pointings to cover M31
while only 2 WFIRST pointings are required.

WFIRST-AFTA using a 2.4-meter telescope is significantly more capable than the smaller versions of WFIRST studied in previous SDTs. Gains of 50-100% or more are expected for each of the core WFIRST-AFTA science programs: dark energy, microlensing, and guest observer observations. Furthermore, the 2.4-m telescope enables new science at the limit of, and beyond, what was achievable with earlier WFIRST designs. With this new telescope, single WFIRST-AFTA images will uncover millions of galaxies. Included in this trove of new data will be hundreds of the analogs of what are today's most precious and rare Hubble discoveries. For example where Hubble has found only a few galaxies within 500 million years of the Big Bang, we now know (from Hubble) that a NRO enabled WFIRST-AFTA will find hundreds of these rare objects. In addition, WFIRST-AFTA now has a coronagraph instrument for direct imaging of ice and gas giant exoplanets. This supplements the microlensing program to give major new capabilities for the study of exoplanets.