  The LOng-Range Reconnaissance Imager (LORRI) is the high resolution imaging
instrument for the New Horizons mission to Pluto, its giant satellite Charon,
its small moons Nix and Hydra, and the Kuiper Belt, which is the vast region of
icy bodies extending roughly from Neptune's orbit out to 50 astronomical units
(AU). New Horizons launched on January 19, 2006 as the inaugural mission in
NASA's New Frontiers program. LORRI is a narrow angle (field of view=0.29 deg),
high resolution (4.95 microrad pixels), Ritchey-Chretien telescope with a 20.8
cm diameter primary mirror, a focal length of 263 cm, and a three lens
field-flattening assembly. A 1024 x 1024 pixel (optically active region),
thinned, backside-illuminated charge-coupled device (CCD) detector is used in
the focal plane unit and is operated in frame transfer mode. LORRI provides
panchromatic imaging over a bandpass that extends approximately from 350 nm to
850 nm. LORRI operates in an extreme thermal environment, situated inside the
warm spacecraft with a large, open aperture viewing cold space. LORRI has a
silicon carbide optical system, designed to maintain focus over the operating
temperature range without a focus adjustment mechanism. Moreover, the
spacecraft is thruster-stabilized without reaction wheels, placing stringent
limits on the available exposure time and the optical throughput needed to
satisfy the measurement requirements.
