The 3-axis spin stabilized Voyager 2 spacecraft was equipped with an enabling scan platform, a challenging limited computer and eight-track digital tape recorder. The mission was designed to take advantage of a planetary alignment that occurs every 175 years. Although Voyager’s goal was to explore Jupiter and Saturn and their environments, different options were reserved for the 2 crafts. Voyager 1 was targeted to Jupiter, Saturn and Titan while the Voyager 2 trajectory allowed it to continue on to Uranus and Neptune.

    Neptune Flyby

    UV to green images are available from 1989-06-05 to 1989-09-29. Closest approach on of the Voyager 2 spacecraft occurred on August 25, 1989 when the spacecraft passed within 4,950 km of the cloud deck and continued on to Triton. Cloud features included the Great Dark Spot. Unlike Jupiter’s Great Red Spot, Neptune’s southern hemispheric feature is not constrained by alternating strong zonal winds. It drifted equatorward and disappeared within five years (as verified by Hubble Space Telescope). White cloud markings that changed rapidly revealed interation of the wind with local weather systems.

    Neptune’s satellites were mapped and five new satellites were discovered. Variation of surface features led school children described Triton as a “rotten cantaloupe”. The variable surface structure and the presence of active vents complicated interpretation of the surface geology. Triton Data and Maps are available.

    The Voyager observations established that the Neptunian arcs are concentrations of particles embedded within Neptune's narrow Adams ring, the outermost of six tenuous rings. Four ring arcs were identified with typical radial widths of 15 km and optical depth of order 0.1.

    The flyby yielded an improved value for Neptune’s mass and revealed a magnetic field that was tilted and offset from the center similar to Uranus’ field.

    References Helpful in Scoping the Mission

    Mission Description
    Spacecraft Description A list of pertinent references
    Also See Space Science Reviews 21 (1977 – Issue 2) 77-101

    Understanding the Instruments and Archived Data

    ISS - Narrow and wide angle cameras with filters in a 280-640 nm range
    IRIS - Infrared Interferometric Spectrometer
    UVS - Ultraviolet Spectrometer
    PPS - Photopolarimeter
    MAG - Triaxial Fluxgate Magnetometer
    LECP - Low Energy Charged Particle Detector
    PLS - Plasma Spectrometer
    PRA - Planetary Radio Astronomy Investigation
    PWS - Planetary Wave Spectrometer
    CRS - Cosmic Ray System
    RSS - Radio Science System

    Other Useful Products for Interpreting the Data

    Locating Voyager Publications
    Geometry in "SPICE" format may be obtained at the NAIF node