Next month, NASA will begin work on its next major space observatory after the James Webb Space Telescope, which is finishing construction for launch in 2018. The new mission is called WFIRST (Wide Field Infrared Survey Telescope) and will investigate dark energy, exoplanets and galaxy formation. It is expected to fly in 2024.
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"Formulation is when we formalize the mission requirements," said David Spergel, co-chair of the WFIRST science definition team, in an e-mail to Discovery News.
"An example of something that we will decide during formulation is the filters that we will use. We need to weigh the relative merits of being sensitive to bluer photons versus having sharper wavelength coverage ... Improved blue sensitivity will help us better characterize the properties of stars in nearby galaxies, but possibly at the cost of less accurate determination of distance to galaxies through photometry."
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WFIRST's advantage is its immense field of view. It uses an old, unflown spy telescope that has the same mirror size as Hubble - 2.4 meters - but a field of view 200 times wider. This will allow it to cover more sky at greater depth in the infrared than any observatory before, Spergel said.