• Cassini: Titan Flyby on May 6, 2016

    From baalke@1:2320/100 to sci.space.news on Wed May 4 23:26:24 2016
    From Newsgroup: sci.space.news


    https://saturn.jpl.nasa.gov/news/2894/

    Cassini
    Titan (T-119): A Unique "Double Midnight" Flyby

    Artist's rendition of the position of Saturn and Titan during T-119

    During Cassini's T-119 Titan flyby on May 6, the Radio Science
    Subsystem, or RSS, will observe an atmospheric occultation, in which
    Cassini appears to go behind Titan's atmosphere as seen from Earth. The
    way the atmosphere modifies Cassini's radio signal will be used to
    profile the thermal structure of the atmosphere and learn more about how
    it varies with Titan's seasons. RSS continues with a short bistatic
    scattering observation, with the radio signal's ground track possibly
    crossing small lakes on Titan. Data from this observation may yield
    information about Titan's surface (including reflectivity, roughness,
    and dielectric constant) that will improve our understanding of the
    moon's composition.

    Key Points

    The T-119 flyby is a unique "double midnight" flyby, in that it occurs
    when Titan is on the night side of Saturn and the closest approach by
    Cassini is on the nightside of Titan as well.

    Scientists have found that Titan's upper atmosphere and ionosphere
    change depending on a variety of factors, including Titan's location in
    its orbit through Saturn's magnetosphere, timing with respect to the
    11-year solar cycle, and the geometry with respect to Titan and
    orientation with respect to the Sun of the closest approach. The only
    way to understand the influence of each of these factors on Titan's
    upper atmosphere and ionosphere is to make observations over a wide
    range of varying geometries.

    During the flyby, the Ion and Neutral Mass Spectrometer, or INMS, will
    make measurements of Titan's atmosphere when the nightside receives the smallest possible infusion of energy from the sun. This helps scientists understand how the sun drives Titan's upper atmospheric chemistry, while density observations provide insight on how quickly Titan's atmosphere
    responds to inputs, relative to the length of Titan's day.

    The Magnetospheric Imaging Instrument, or MIMI, will measure the
    energetic ion and electron environment during the flyby. MIMI data will
    be used to estimate the energetic particle input from the magnetosphere
    into Titan's atmosphere and ionosphere. This will help interpret the atmospheric characteristics (the ionization layers and scale heights)
    observed by RSS. Cassini's observations have demonstrated that the magnetospheric environment near Titan is much more variable and complex
    than scientists could ever have anticipated.



    Titan Flyby at a Glance

    Date
    May 6, 2016

    Altitude
    603 mi (971 km)

    Speed (relative to Titan)
    13,198 mph (5.9 km/sec)

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