Wide Field Infrared Survey Telescope
Rendered model of the WFIRST spacecraft
|Names||Joint Dark Energy Mission|
|Mission type||Infrared Space observatory|
|Operator||NASA / JPL / GSFC|
|Mission duration||6 years (planned)|
|Launch mass||4,166 kg (9,184 lb)|
|Dry mass||4,059 kg (8,949 lb)|
|Payload mass||2,191 kg (4,830 lb)|
|Start of mission|
|Rocket||Delta IV Heavy or Falcon Heavy|
|Contractor||United Launch Alliance|
|Reference system||Sun–Earth L2|
|Periapsis||188,420 km (117,080 mi)|
|Apoapsis||806,756 km (501,295 mi)|
|Diameter||2.4 m (7 ft 10 in)|
|Wavelengths||near-infrared, visible light|
|Band||S band (TT&C support)
Ka band (data acquisition)
|Bandwidth||few kbit/s down & up (S band)
290 Mbit/s (Ka band)
Wide Field Instrument
The Wide Field Infrared Survey Telescope (WFIRST) is a proposed infrared space observatory which was selected by National Research Council committee as the top priority for the next decade of astronomy.
The design of WFIRST is based on one of the proposed designs for the Joint Dark Energy Mission between NASA and DOE. WFIRST adds some extra capabilities to the original JDEM proposal, including a search for extra-solar planets using gravitational microlensing. In its present incarnation, a large fraction of its primary mission will be focused on probing the expansion history of the Universe and the growth of cosmic structure with multiple methods in overlapping redshift ranges, with the goal of precisely measuring the effects of dark energy, the consistency of General Relativity, and the curvature of spacetime.
The original design of WFIRST (Design Reference Mission 1), studied in 2011–2012, featured a 1.3 m (4 ft 3 in) diameter unobstructed three-mirror anastigmat telescope. It contained a single instrument, a visible to near-infrared imager/slitless prism spectrometer. In 2012, another possibility emerged: NASA could use a second-hand National Reconnaissance Office telescope made by Harris Corporation to accomplish a mission like the one planned for WFIRST. NRO offered to donate two telescopes, the same size as the Hubble Space Telescope but with a shorter focal length and hence a wider field of view. This provided important political momentum to the project, even though the telescope only represents a modest fraction of the cost of the mission and the boundary conditions from the NRO design may push the total cost over that of a fresh design. This mission concept, called WFIRST-AFTA (Astrophysics Focused Telescope Assets), is being matured by a scientific and technical team; this mission is now the only present NASA plan for the use of the NRO telescopes. The WFIRST-AFTA baseline design now includes a coronagraph which requires extreme optothermal stability to enable the direct imaging of exoplanets.
The study phase is led by a team at NASA's Goddard Space Flight Center in Greenbelt, Maryland. The Project Scientist for WFIRST is Neil Gehrels; the Study Manager is Kevin Grady; the Program Scientist is Dominic Benford; the Program Executive is John Gagosian; the Formulation Science Working Group is chaired by Gehrels with Deputy Chairs David Spergel and Jeremy Kasdin.
In fiscal year 2014 Congress provided $56 million for WFIRST, and in 2015 Congress provided $50 million. The fiscal year 2016 spending bill provided $90 million for WFIRST, far above NASA's request of $14 million, allowing the mission to enter the 'formulation phase' in February 2016. 
The science objectives of WFIRST aim to address cutting edge questions in cosmology and exoplanet research, including:
- Answer basic questions about dark energy, complementary to the ESA EUCLID mission, and include: Is cosmic acceleration caused by a new energy component or by the breakdown of General Relativity on cosmological scales? If the cause is a new energy component, is its energy density constant in space and time, or has it evolved over the history of the universe? WFIRST will use three independent techniques to probe dark energy:
- Complete a census of exoplanets to help answer new questions about the potential for life in the universe: How common are solar systems like our own? What kinds of planets exist in the cold, outer regions of planetary systems? – What determines the habitability of Earth-like worlds? This census makes use of a technique that can find exoplanets down to a mass only a few times that of the Moon:
- Establish a guest investigator mode enabling survey investigations to answer diverse questions about our galaxy and the universe.
- Provide a coronagraph for exoplanet direct imaging that will provide the first direct images and spectra of planets around our nearest neighbors similar to our own giant planets.
WFIRST-AFTA will have two instruments. The Wide-Field Instrument (WFI) is a 288-megapixel camera with a 0.28 square degree field of view providing multi-band near-infrared (0.7 to 2.0 micron) imaging using a HgCdTe focal-plane array with a pixel size of 110 milliarcseconds. It includes a grism for wide-field slitless spectroscopy and an integral field spectrograph for small-field spectroscopy. The second instrument is a high contrast coronagraph covering shorter wavelengths (0.4 to 1.0 micrometers) using novel starlight-suppression technology. It is intended to achieve a part-per-billion suppression of starlight to enable the detection of planets only 0.1 arcseconds away from their host stars which will require extreme optothermal stability.
- "WFIRST-AFTA Observatory". NASA Goddard Space Flight Center. 25 April 2014. Retrieved 2015-06-10.
- "WFIRST-AFTA Science Definition Team Final Report" (PDF). NASA Goddard Space Flight Center. 13 February 2015. Retrieved 2015-06-10.
- National Research Council (2010). New Worlds, New Horizons in Astronomy and Astrophysics. Washington, D.C.: National Research Council. ISBN 0-309-15802-8. Retrieved 27 January 2011.
- WFIRST Wide-Field Infrared Telescope Home Page, http://wfirst.gsfc.nasa.gov/about/
- WFIRST Science Definition Team Final Report (PDF), 2012-08-15, retrieved 2013-09-10
- "Ex-Spy Telescope May Become a Space Investigator - NYTimes.com". 2012-06-04. Retrieved 2012-06-10.
- WFIRST-AFTA SDT Final Report, revision 1 (PDF), 2013-05-23, retrieved 2013-09-10
- Dan Leone (2013-06-04). "Only NASA Astrophysics Remains in Running for Donated NRO Telescope — For Now; SpaceNews article". Retrieved 2013-09-10.
- NASA (2014-04-30). "WFIRST Science Definition Team Interim Report" (PDF). Retrieved 2014-08-28.
- Foust, Jeff (7 January 2016). "NASA's Next Major Space Telescope Project Officially Starts in February". Space.com. Retrieved 2016-01-09.
|Wikimedia Commons has media related to Wide Field Infrared Survey Telescope.|
- WFIRST-AFTA page at Goddard Space Flight Center site
- WFIRST Science Data Center page at the Infrared Processing and Analysis Center (IPAC)
- $1.6 Billion Telescope Would Search Alien Planets and Probe Dark Energy — Space.com
- The WFIRST/AFTA astrophysics mission: bigger and better for exoplanets, Tom Greene
- on YouTube (min. 1:25)
- on YouTube (min. 4:20)