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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. WFIRST will also attempt to detect the nature of dark energy.〔WFIRST Wide-Field Infrared Telescope Home Page, http://wfirst.gsfc.nasa.gov/about/〕 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 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 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 mission will remain in this 'pre-formulation' phase until at least early 2016. The WFIRST-AFTA baseline design now includes a coronagraph which requires extreme optothermal stability to enable the direct imaging of exoplanets.〔 〕 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. 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 == The science objectives of WFIRST overlap those of the EUCLID mission that ESA plans to launch in 2020, and include: * 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: * * Baryon acoustic oscillations * * Observing distant supernovae * * Weak gravitational lensing * 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: * * Gravitational microlensing * 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Wide Field Infrared Survey Telescope」の詳細全文を読む スポンサード リンク
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