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CASSINI-HUYGENS Descent Imager/Spectral Radiometer (DISR)

Descent Imager / Spectral Radiometer (DISR), is a scientific instrument designed to explore Saturn’s largest moon Titan. It was launched in October 1997, on board the European Space Agency’s Huygens Probe, as part of the Cassini Mission to Saturn. The DISR will make a pioneering effort to obtain close-up pictures of Titan’s surface and determine the nature Titan’s atmosphere.

Cassini Spacecraft will enter orbit around Saturn in 2004. The Huygens Probe will detach from the spacecraft in late 2004 to enter the atmosphere of Titan. For about 2 hours and 15 minutes the probe will fall from 160 km altitude to Titan’s surface. During the descent the DISR and 5 other science instruments will send data about the moon’s atmosphere and surface back to the spacecraft for relay to Earth.

R measures solar radiation using silicon photodiodes, a two-dimensional silicon Charge Coupled Device (CCD) detector and two InGaAs near-infrared linear array detectors. The light is brought to the detectors using fibre optics from many separate sets of foreoptics that collect light from different directions and in different spectral regions. In this way the instrument can make a suite of measurements that are carefully selected to answer key questions concerning the nature of the surface and the composition, meteorology, thermal balance, and clouds and aerosols in the atmosphere of Titan.


Martin Tomasko
University of Arizona Lunar and Planetary Laboratory


University of Arizona Lunar and Planetary Laboratory, U.S. Geological Survey, NASA Jet Propulsion Laboratory

Observatoire de Paris Meudon, Laboratory of Glaciology and Geophysics of Grenoble

Lawrence Berkeley National Laboratory

Technical University of Bruanschweig, Max Planck Institute for Aeronomy in Lindau

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