Instrument Investigators Description Some Scientific Objectives

Imaging Science Instrument

An optical remote-sensing instrument

Investigator Team Lead: Carolyn Porco

Space Science Institute, Boulder, Colorado

ISS comprises two telescopes:

Wide Angle Camera: a 5.7-cm aperture f/3.5 refracting telescope with a 3.5° field of view and an angular resolution of 60 microradians per pixel.

Narrow Angle Camera: a 19-cm aperture f/10.5 Cassegrain telescope with a 0.35° field of view and an angular resolution of 6.0 microradians per pixel.

Each has a 10242 pixel CCD detector, fitted with spectral filters that rotate on a wheel to view wavelength bands from 0.2 microns to 1.1 microns. The Wide Angle Camera has 18 filters ranging from 380 to 1100 nm, and the Narrow Angle has 24, from 200 to 1100 nm. The ISS data system allows many options, including on-chip summing and data compression.

Within Saturn's and Titan's atmospheres, to map 3D structure and motions, study composition, distribution, and physical properties of clouds and aerosols, investigate scattering, absorption, and solar heating, and search for evidence of lightning, aurorae, airglow, and planetary oscillations;

Study gravitational interactions between rings and satellites, determine rate, and nature, of energy and momentum transfer within the rings; determine ring thickness, and the sizes, composition, and physical nature of ring particles, map surfaces of the satellites, including Titan. Many more objectives.

All of Cassini's optical remote-sensing instruments, including ISS, are rigidly mounted on the on the plus-X side of the spacecraft, with their apertures (seen with red aperture covers in the photograph) directed toward minus-Y. Detector electronics are cooled by passive radiation from dedicated radiator plates that face in the plus-X direction into deep, cold space. Pointing the optical instruments at their targets requires rotating the entire spacecraft.

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Science Instruments in the Basics of Space Flight