Wide Field Infrared Survey Telescope

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Wide Field Infrared Survey Telescope - Astrophysics Focused Telescope Assets
3D image of WFIRST spacraft
Artist's impression of the WFIRST spacecraft
Names Joint Dark Energy Mission
Mission type Infrared Space observatory
Operator NASA / JPL / GSFC
Website wfirst.gsfc.nasa.gov
Mission duration 6 years (planned)[1]
Spacecraft properties
Manufacturer ITT/Exelis
Launch mass 4,166 kg (9,184 lb)[2]
Dry mass 4,059 kg (8,949 lb)[2]
Payload mass 2,191 kg (4,830 lb)[2]
Power 2500 watts
Start of mission
Launch date mid-2020s
Rocket Delta IV Heavy[2]
Contractor United Launch Alliance
Orbital parameters
Reference system Geocentric
Regime Geostationary[2]
Longitude 105° west
Inclination 28.5°
Period 24 hours
RAAN 175°
Epoch planned
Main telescope
Type Three-mirror anastigmat
Diameter 2.4 m (7 ft 10 in)
Wavelengths near-infrared, visible light
Transponders
Band S Band (TT&C support)
Ka band (data acquisition)
Bandwidth few kbit/s down & up (S Band)
600 Mbit/s or 1.2 Gbit/s (Ka Band)
Instruments
Coronagraph Instrument
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.[3] WFIRST will also attempt to detect the nature of dark energy.[4] 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. [5] 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 to accomplish a mission like the one planned for WFIRST. NRO offered to donate two telescopes, the same size as the Hubble Space Telescope with a wider field of view.[6] This mission concept, called WFIRST-AFTA (Astrophysics Focused Telescope Assets), is being matured by a scientific and technical team;[7] this mission is now the only present NASA plan for the use of the NRO telescopes.[8] The mission will remain in this 'pre-formulation' phase until at least early 2016.[9] The WFIRST-AFTA baseline design now includes a coronagraph to enable the direct imaging of exoplanets.[10]

As of March 4, 2014, the President's FY15 budget request includes a line item for WFIRST/AFTA development, including a budget ramp-up consistent with the mid-2020s launch date.[11] 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 Lia Lapiana; the Science Definition Team is jointly led by Gehrels and David Spergel.

Science objectives[edit]

  • Answer basic questions about dark energy: 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.

References[edit]

  1. ^ "WFIRST-AFTA Observatory". NASA Goddard Space Flight Center. 25 April 2014. Retrieved 2015-06-10. 
  2. ^ a b c d e "WFIRST-AFTA Science Definition Team Final Report" (PDF). NASA Goddard Space Flight Center. 13 February 2015. Retrieved 2015-06-10. 
  3. ^ 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. 
  4. ^ WFIRST Wide-Field Infrared Telescope Home Page, http://wfirst.gsfc.nasa.gov/about/
  5. ^ WFIRST Science Definition Team Final Report (PDF), 2012-08-15, retrieved 2013-09-10 
  6. ^ "Ex-Spy Telescope May Become a Space Investigator - NYTimes.com". 2012-06-04. Retrieved 2012-06-10. 
  7. ^ WFIRST-AFTA SDT Final Report, revision 1 (PDF), 2013-05-23, retrieved 2013-09-10 
  8. ^ Dan Leone (2013-06-04). "Only NASA Astrophysics Remains in Running for Donated NRO Telescope — For Now; SpaceNews article". Retrieved 2013-09-10. 
  9. ^ Paul Hertz (2013-06-04), NASA Astrophysics presentation to American Astronomical Society (PDF), retrieved 2013-09-10 
  10. ^ NASA (2014-04-30). "WFIRST Science Definition Team Interim Report" (PDF). Retrieved 2014-08-28. 
  11. ^ Beth Robinson (2014-03-04). "Presentation by NASA CFO Beth Robinson" (PDF). Retrieved 2014-03-04. 

External links[edit]