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Cassini continues its exploration of the Saturn system with the 12-day Rev182, which begins on February 20 at its farthest distance from the planet. This is also called the orbit's apoapse. At this point, Cassini is 1.47 million kilometers (0.91 million miles) from Saturn's cloud tops. Rev 182 occurs nine months 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. Eight ISS observations are planned for Rev 182.
On February 22, ISS begins its observations for Rev 182 two days after apoapse with a distant observation of Titan. ISS will be riding along with the Composite Infrared Spectrometer (CIRS) during this 11-hour observation. The camera system will be monitoring clouds that may exist across the moon's southern trailing and sub-Saturn hemispheres. On February 23, 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 February 26 at 04:27 UTC, Cassini will reach periapse for Rev 182 at an altitude of 424,780 kilometers (263,950 miles) from Saturn. On February 25, ISS will monitor the south polar plume of Enceladus from a distance of 660,000 kilometers (410,000 miles). Late on February 26 and early on the 27th, ISS will ride along with 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 like it did in November. On February 27, ISS will track cloud features as they rotate on Saturn. Images will be taken at a variety of latitudes at low, medium, and high emission angles to see how these features different in appearance at different viewing angles. This is useful to understand the structure of Saturn's high-altitude haze layers.
On the outbound leg of Rev182, ISS will focus on Saturn's distant, outer satellites. On February 28 and March 1, ISS will acquire three observations of these small moons, two focused on Hati and another that will take a look at Erriapus. These three observations will be used to measure the rotation period of the two moons. Given their small size and great distance from Saturn, they do not rotate synchronously like Saturn's closer and larger icy moons. Hati is six kilometers (3.7 miles) across and will be 16.5 million kilometers (10.2 million miles) away. Erriapus is 10 kilometers (6.2 miles) across and will be 26.6 million kilometers (16.5 million miles) away.
On March 4, Cassini will reach apoapse on this orbit, bringing it to a close and starting Rev183. The next orbit includes a targeted encounter with Rhea.
Image products created in Celestia. All dates in Coordinated Universal Time (UTC).