|
Документ взят из кэша поисковой машины. Адрес
оригинального документа
: http://www.stsci.edu/institute/wfirst/obsoverview
Дата изменения: Unknown Дата индексирования: Sun Apr 10 15:16:26 2016 Кодировка: Поисковые слова: interstellar medium |
The WFIRST Observatory uses an existing 2.4m AFTA (Astrophysics-Focused Telescope Assets) telescope, donated to NASA by the National Reconnaissance Office (NRO). The design reference mission described in the Final Report of the WFIRST-AFTA Science Definition Team has two instruments to execute the mission science program:
The baseline WFIRST mission duration in the design reference mission is 6 years, with observations to be performed as listed below. At the end of its 6-year baseline mission, WFIRST should be able to continue scientific investigations during an extended mission phase (subject to NASA review and the continued availability of funding). Mission consumables will be sized to allow operation for a minimum of 10 years. The observatory design, instrument capabilities, and observing programs may all continue to evolve as the mission matures through its formulation and design phases. The relevant science and hardware trade studies will be informed by input from the Formulation Science Working Group and the astronomical community.
A high-latitude WFI galaxy survey (HLS), taking a total of 2 years. The HLS will cover over 2,200 square degrees with imaging and low-resolution (grism) spectroscopy. The imaging, in four NIR bands (Y, J, H, and F184), will reach J=26.7 AB for point sources. The spectroscopy will measure redshifts for over 15 million sources at redshift 1.1 to 2.8. Imaging and spectroscopy will support dark energy weak lensing and baryon acoustic oscillation measurements, respectively, and form an invaluable survey for Archival Guest Investigator studies of General Astrophysics topics.
A three-tiered WFI supernova survey, with both imaging and IFU spectroscopy, taking a total of 0.6 years. The imaging survey is designed in three tiers, shallow, medium, and deep, to find supernovae at redshift < 0.4, < 0.8, and < 1.7, respectively. The three tiers will cover approximately 27, 9, and 5 square degrees, respectively, with observations repeated with a cadence of 5 days, in filters Y and J for the shallow tier, and J and H for the medium and deep tier. IFU spectrophotometric observations will be used to fully characterize the type and light curve of a subset of 2700 supernovae, chosen to sample the full redshift range. These survey data will also be useful for Archival Guest Investigator studies of General Astrophysics topics.
A WFI microlensing survey of the Milky Way Bulge, taking a total of 1 year. Ten fields will be imaged every 15 minutes over contiguous 72-day periods ("seasons"), to create highly-sampled light curves of 56 million stars brighter than H=21.6 (AB). Six such seasons will be executed over the mission lifetime, resulting in the expected discovery of over 2000 bound planets in the range 0.1-1000 Earth masses and orbital major axes from 0.03 to 30 AU through their microlensing signature. About 20,000 giant planets in short-period orbits will be detected from their transit signature. These survey data will also be useful for Archival Guest Investigator studies of General Astrophysics topics.
A coronagraphic observing program, taking a total of 1 year. Initial observations will focus on discovery and characterization of planets around pre-selected target stars. When a previously known or unknown planet is detected, additional observations will be made for longer time periods, with full spectral resolution for planet characterization. Dozens of planets will be targeted in this manner.
A GO program, taking a total of 1.4 years. Observations covering all areas of astrophysics will be competitively selected through peer review, in the same spirit as for other NASA Great Observatories. The programs can use any of the available instruments and modes.