Instrument Investigators Description Some Scientific Objectives
VIMS

Visual and Infrared Imaging Spectrometer

An optical remote-sensing instrument

Investigator Team Lead: Robert Brown

Lunar and Planetary Lab, University of Arizona

VIMS consists of two telescopes designed to measure reflected and emitted radiation from atmospheres, rings, and surfaces. Each has a 32 microradian2 field of view.

Infrared channel, sensitive from 0.35 to 1.07 Ám, consists of a 23 cm aperture Cassegrain telescope, spectrometer grating, and 256-element linear indium antimonide array focal plane assembly. The instantaneous field of view is a single pixel; a two-dimensional image is created using a two-axis scanning mirror.

Visible channel, sensitive from 0.85 to 5.1 Ám, consists of a 4.5 cm aperture Shafer telescope, holographic spectrometer grating, and 256 x 512-pixel silicon CCD area array focal plane detector. Instantaneous field of view is an entire line of pixels; a single-axis scanning mirror produces a two-dimensional image.

VIMS' ability to move its mirrors to obtain spectra of different parts of target objects, without having to reposition the entire spacecraft to do so, makes it a "mapping spectrometer."

To map the temporal behavior of winds, eddies, and other features on Saturn and Titan, and study the composition and distribution of atmospheric and cloud species;

Determine the composition and distribution of the icy satellite surface materials;

To determine temperatures, internal structure, and rotation of Saturn's deep atmosphere;

Study the structure and composition of Saturn's rings;

Search for lightning on Saturn and Titan and for active volcanism on Titan, and observe Titan's surface.

All of Cassini's optical remote-sensing instruments, including VIMS, 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.

More on VIMS

Back to Cassini in the Basics of Space Flight

Science Instruments in the Basics of Space Flight