Imaging Science (ISS)

Description

The photographic experiment used a two-camera system, based on the Mariner 10 system. This system included one narrow-angle, long-focal-length camera and one wide-angle, short-focal-length camera. The maximum resolution achievable depended greatly on the actual trajectory on this multi-encounter mission, but was as high as 0.5 to 1.0 km on the closest approaches to some objects. At Jupiter and Saturn, the resolution that was achieved was better than 20 km and 5 km, respectively. The objectives of the experiment were to photograph global motions and cloud distributions (on Jupiter, Saturn, Uranus, and Neptune), gross dynamical properties, zonal rotations, orientation of spin axes, zonal shear, vertical shear, flow instabilities, spots, and spectrum of scale of atmospheric motions in time and space. Additional objectives included the study of the mode of release of internal energy flux (search for convection cells and rolls), study of growth, dissipation, morphology, and vertical structure of cloud complexes, gross optical properties, global and localized scattering function in the visible spectrum, polarimetry, nature of chromophores (their structure and development), and high resolution of the Great Red Spot. The objectives of the satellite encounters included (1) gross characteristics (size, shape, rotation, spin axis, cartography, improved ephemerides and masses); (2) geology (major physiographic provinces, impact and volcanic features, lineaments, polar caps, erosion processes, and low- and high-density satellite comparative studies, detection of atmospheres, frosts, and limb stratification of aerosols); and (3) surface properties (colorimetry, scattering function, nature of brightness variation, and search for new satellites). Studies of Saturn's rings were carried out and will be for Uranus' rings. Objectives included (1) resolution of individual ring components of clumps of material; (2) vertical and radial distribution of material at very high resolution; (3) scattering function; (4) coarse polarimetry; (5) occultation - optical depth; and (6) distinguishing different types of material in the rings. Other objectives were to search for new comets, asteroids, and targets of opportunity.