  The New Horizons ALICE instrument is a lightweight (4.4 kg), low-power (4.4
Watt) imaging spectrograph aboard the New Horizons mission to Pluto/Charon and
the Kuiper Belt. Its primary job is to determine the relative abundances of
various species in Pluto's atmosphere. ALICE will also be used to search for an
atmosphere around Pluto's moon, Charon, as well as the Kuiper Belt Objects
(KBOs) that New Horizons hopes to fly by after Pluto-Charon, and it will make
UV surface reflectivity measurements of all of these bodies as well. The
instrument incorporates an off-axis telescope feeding a Rowland-circle
spectrograph with a 520-1870 angstroms spectral passband, a spectral point
spread function of 3-6 angstroms FWHM, and an instantaneous spatial
field-of-view that is 6 degrees long. Different input apertures that feed the
telescope allow for both airglow and solar occultation observations during the
mission. The focal plane detector is an imaging microchannel plate (MCP) double
delay-line detector with dual solar-blind opaque photocathodes (KBr and CsI)
and a focal surface that matches the instrument's 15-cm diameter
Rowland-circle. In what follows, we describe the instrument in greater detail,
including descriptions of its ground calibration and initial in flight
performance.
