CASSINI HUYGENS SCIENCE INSTRUMENTS, SPACECRAFT, AND MISSION/

The Cassini spacecraft will take 18 scientific instruments to Saturn. After launch and a seven-year cruise, Cassini will arrive at Saturn an d separate into a Saturn orbiter and an atmospheric probe, called Huyg ens, which will descend to the surface of Titan. The orbiter will orbi t the planet for four years, making close flybys of five satellites, i ncluding multiple flybys of Titan. Communication with Earth is at X-ba nd; the maximum downlink rate from Saturn is 166 x 10(3) bps. Orbiter instruments are body mounted; the spacecraft must be turned to point s ome of them toward objects of interest. The orbiter carries 12 instrum ents. Optical instruments provide imagery and spectrometry, Radar supp lies imaging, altimetry, and radiometry. Radio links contribute inform ation about intervening material and gravity fields. Other instruments measure electromagnetic fields and the properties of plasma, energeti c particles, and dust particles. The probe is spin stabilized. It retu rns data via an S-band link to the orbiter. The probe's six instrument s include sensors to determine atmospheric physical properties and com position. Radiometric and optical sensors will produce data on thermal balance and obtain images of Titan's atmosphere and surface. Doppler measurements between probe and orbiter will provide wind profiles. Sur face sensors will measure impact acceleration, thermal and electrical properties, and, if the surface is liquid, density and refractive inde x. This design will enable Cassini to determine the composition; the p hysical, morphological, and geological nature; and I the physical and chemical processes of the atmospheres, surfaces, and magnetosphere of the Saturnian system. This paper briefly describes the Cassini mission and spacecraft and, in somewhat more detail, the scientific instrumen ts.