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⪅Destiny is a simple, direct, low cost mission to determine the properties of dark energy by obtaining a cosmologically
deep supernova (SN) type Ia Hubble diagram. Its science instrument is a 1.65m space telescope, featuring a grism-fed
near-infrared (NIR) (0.85-1.7 μm) survey camera/spectrometer with a 0.12 square degree field of view (FOV) covered
by a mosaic of 16 2k x 2k HgCdTe arrays. For maximum operational simplicity and instrument stability, Destiny will be
deployed into a halo-orbit about the Second Sun-Earth Lagrange Point. During its two-year primary mission, Destiny
will detect, observe, and characterize ~3000 SN Ia events over the redshift interval 0.4 < z < 1.7 within a 3 square
degree survey area. In conjunction with ongoing ground-based SN Ia surveys for z < 0.8, Destiny mission data will be
used to construct a high-precision Hubble diagram and thereby constrain the dark energy equation of state. The total
range of redshift is sufficient to explore the expansion history of the Universe from an early time, when it was strongly
matter-dominated, to the present when dark energy dominates. The grism-images will provide a spectral resolution of
R≡λ/Δλ=75 spectrophotometry that will simultaneously provide broad-band photometry, redshifts, and SN
classification, as well as time-resolved diagnostic data, which is valuable for investigating additional SN luminosity
diagnostics. Destiny will be used in its third year as a high resolution, wide-field imager to conduct a multicolor NIR
weak lensing (WL) survey covering 1000 square degrees. The large-scale mass power spectrum derived from weak
lensing distortions of field galaxies as a function of redshift will provide independent and complementary constraints on
the dark energy equation of state. The combination of SN and WL is much more powerful than either technique on its
own. Used together, these surveys will have more than an order of magnitude greater sensitivity (by the Dark Energy
Task Force's (DETF) figure of merit) than will be provided by ongoing ground-based projects. The dark energy
parameters, w0 and wa, will be measured to a precision of 0.05 and 0.2 respectively.
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