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Cassini continues its exploration of the Saturn system with the 12-day Rev 192, which begins on June 7 at its farthest distance from the planet. This is also called the orbit's apoapse. At this point, Cassini is 1.34 million kilometers (0.83 million miles) from Saturn's cloud tops. Rev 192 occurs a year into the first inclined phase of the Cassini Solstice Mission, a phase which lasts until March 2015. The inclined phase will allow for polar views of Saturn and Titan as well as better vistas of Saturn's rings than those Cassini had while in the earlier, equatorial phase of the Solstice Mission. Twenty ISS observations are planned for Rev 192 with many focused on Saturn's atmosphere and rings.
On June 9, a couple of days after apoapse, ISS will ride along with an Ultraviolet Imaging Spectrometer (UVIS) observation of Saturn's south polar aurora. In addition to making a movie of the planet's aurorae, the images will be used to independently measure the rotation period of Saturn's magnetic field. On June 10, ISS will acquire a distant observation of a crescent Titan. These images will be taken from a distance of 1.43 million kilometers (0.89 million miles) and will be used to study Titan's upper haze layers. On June 12 and 14, ISS will acquire three observations of the small, outer satellite, Albiorix. Previous imaging of the satellite showed that it takes a little over 13 hours to rotate once, much faster than it takes to go around Saturn once (2.15 Earth years). These three observations, combined with the earlier rotational light curves, will be used to determine the orientation of its rotation axis. Albiorix is 32 kilometers (20 miles) across and will be 22.9 million kilometers (14.2 million miles) away. Between the two Albiorix observations, on June 12, ISS will monitor the south polar plume of Enceladus from a distance of 713,890 kilometers (443,590 miles).
On June 13 at 05:58 UTC, Cassini will reach periapse for Rev 192 at an altitude of 557,700 kilometers (346,540 miles) from Saturn. A few hours after periapse, ISS will ride along with the Visual and Infrared Mapping Spectrometer (VIMS) to acquire a mosaic of Saturn's north polar region using the Wide-Angle Camera (WAC). Spring has progressed far enough that the entirety of the hexagonal jet stream that lies near 77 degrees North latitude will be in sunlight. ISS will be imaging the hexagon with a two-by-two mosaic rather than centering the field-of-view on the north pole. On June 14, ISS will acquire a nine-hour movie of Saturn's north polar vortex using both the narrow and wide-angle cameras. The movie will be used to study the dynamics of cloud features near Saturn's north pole. Afterward, ISS will look for clouds across Titan's sub-Saturn hemisphere from a distance of 1.95 million kilometers (1.21 million miles).
On June 15, ISS will acquire a pair of quick observations of Saturn using the WAC. These observations are part of a series of "Storm Watch" observation sequences designed to take advantage of short, two-minute segments when the spacecraft turns the optical remote sensing (ORS) instruments back to Saturn as a waypoint between other experiments' observations. These sequences include blue, clear, two methane band, and one full-frame, continuum band filter images. Three more observations are planned for June 16. Between the two storm watch observations on June 15, ISS will ride-along with the Composite Infrared Spectrometer (CIRS) to observe the opposition surge on Saturn's rings, including a few images using polarized filters. By observing the brightness and the size of the opposition surge, an estimate of grain size of the particles in the rings can be calculated. After the second storm watch observation, ISS will ride-along with the Ultraviolet Imaging Spectrometer (UVIS) to observe the icy moon Tethys from a distance of 811,890 kilometers (504,490 miles). Finally, ISS will acquire an astrometric observation of Saturn's small, inner moons. Astrometric observations are used to improve our understanding of the orbits of these small satellites, which can be influenced by Saturn's larger icy moons.
On June 16, after the astrometric observation, ISS will take another look at Titan, looking for clouds across the moon's sub-Saturn hemisphere from a distance of 2.33 million kilometers (1.45 million miles). Next, ISS will image the outer A ring, where it will be looking at propellers previously imaged by Cassini. Propellers are small voids in Saturn's rings created by the gravitational interaction between large ring particles and the surrounding ring. Finally, ISS will observe several faint rings from a vantage point near the ring plane, including the E ring and the Anthe ringlet.
On June 19, Cassini will reach apoapse, bringing Rev 192 to a close and starting the next orbit, Rev 193.
Image products created in Celestia. All dates in Coordinated Universal Time (UTC).