  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 $\mu$m 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 0.02e$-$/s. Each
sensor chip assembly has 2048 x 2048 square pixels of 18 $\mu$m size (0.15
arcsec), sensitive in the 0.8 to 1.7 $\mu$m 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.
