Alice (spacecraft instrument)


Alice is an ultraviolet imaging spectrometer for spacecraft, with one used on the New Horizons spacecraft, and another on the Rosetta spacecraft. Alice is a small telescope with spectrograph and a special detector with 32 pixels each with 1024 spectral channels detecting ultraviolet light.
Alice has an off-axis telescope which sends light to a Rowland-circle spectrograph, and the instrument has a field of view of 6 degrees. It is designed to capture airglow and solar occultation at the same time, and has two inputs to allow this.

Overview

Alice uses an array of potassium bromide and caesium iodide type photocathodes. It detects in the extreme and far ultraviolet spectrum, from wavelengths of light.
Alice is intended, among its capabilities, to detect ultraviolet signatures of noble gases including helium, neon, argon, and krypton. Alice should also be able to detect water, carbon monoxide, and carbon dioxide in the ultraviolet.
ALICE was built and operated by the Southwest Research Institute for NASA's Jet Propulsion Laboratory.

Naming

Alice is named after a character in The Honeymooners, along with another New Horizons instrument, Ralph.

Alice on ''New Horizons''

In August 2018, NASA confirmed, based on results by Alice on the New Horizons spacecraft, the detection of a "hydrogen wall" at the outer edges of the Solar System that was first detected in 1992 by the two Voyager spacecraft which have detected a surplus of ultraviolet light determined to be coming from hydrogen.
The New Horizons version of Alice uses an average power of 4.4 watts and weighs 4.5 kg.

Alice on ''Rosetta''

On Rosetta, a mission to a comet, Alice performed ultraviolet spectroscopy to search and quantify the noble gas content in the comet nucleus.
On Rosetta it is a instrument which uses 2.9 watts.