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DUNE (Dark Universe Explorer) is a proposed mission to measure parameters of dark energy using weak gravitational
lensing The particular challenges of both optical and infrared focal planes and the DUNE baseline solution is discussed.
The DUNE visible Focal Plane Array (VFP) consists of 36 large format red-sensitive CCDs, arranged in a 9x4 array
together with the associated mechanical support structure and electronics processing chains. Four additional CCDs
dedicated to attitude control measurements are located at the edge of the array. All CCDs are 4096 pixel red-enhanced
e2v CCD203-82 devices with square 12 μm pixels, operating from 550-920nm. Combining four rows of CCDs provides
a total exposure time of 1500s. The VFP will be used in a closed-loop system by the spacecraft, which operates in a drift
scan mode, in order to synchronize the scan and readout rates. The Near Infrared (NIR) FPA consists of a 5 x 12 mosaic
of 60 Hawaii 2RG detector arrays from Teledyne, NIR bandpass filters for the wavelength bands Y, J, and H, the
mechanical support structure, and the detector readout and signal processing electronics. The FPA is operated at a
maximum temperature of 140 K for low dark current of 0.02-/s. Each sensor chip assembly has 2048 x 2048 square
pixels of 18 μm size (0.15 arcsec), sensitive in the 0.8 to 1.7 μm wavelength range. As the spacecraft is scanning the sky,
the image motion on the NIR FPA is stabilized by a de-scanning mirror during the integration time of 300 s per detector.
The total integration time of 1500 seconds is split among the three NIR wavelengths bands. DUNE has been proposed to
ESA's Cosmic Vision program and has been jointly selected with SPACE for an ESA Assessment Phase which has led
to the joint Euclid mission concept.
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