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Cassiniís journey at Saturn continues with Rev 63, its 64th orbit of the ringed planet. During the last few months of the Cassini primary mission, the trips around Saturn are coming fast and furious, and this orbit lasts a scant nine days. As such, Cassiniís slate of observations is more tightly focused, with sequences involving Titan and Saturnís atmosphere, small satellites, and rings on the schedule. Cassini begins Rev63, on March 28 at its farthest distance from Saturn, called apoapsis. At this point, Cassini is 1.48 million km (917,000 mi) from Saturn. On the first day of Rev63, the spacecraft will observe Titan from a distance of 1.28 million km (795,000 mi). Cassini will observe the haze layers above the moonís north polar region, as well as the surface north of Belet and Senkyo. This region includes the two, large north-polar seas. On March 28 and 30, Cassini performs observations of several of Saturnís small satellites. The observations are designed to study the orbits of these objects and how they might evolve over short periods due to perturbations from the other satellites in the system. Also, on March 28 and 29, Cassini will observe Saturnís northern hemisphere for 14 and 8.4 hours, respectively. These observations will allow atmospheric scientists to measure cloud motions and wind speeds on this part of the planet. Northern spring is approaching on Saturn, and the science team will compare their results to prior measurements to see if these atmospheric motions have changed as the ring shadows recede and the Sun rises higher in the sky. On April 1, Cassini reaches periapse, the closest point in its orbit of Saturn. At that point, Cassini will be 259,000 km (161,000 mi) from Saturnís cloud tops. Between March 31 and April 3, Cassini will perform a number of observations of Saturnís ring system, including a UVIS occultation and several scans looking for spokes in the B ring. On March 31 and April 1, CIRS will perform two mid-infrared scans of the rings: first a radial scan from the A ring to the D ring, and then an azimuthal scan of the outer A ring. Between those two CIRS scans, ISS will observe portions of the outer C ring with its narrow-angle camera, and UVIS will perform a stellar occultation of the rings by observing variations in the brightness of the star Alpha Arae as it passes behind the rings. ISS will ride along with UVIS, observing scattering effects and the dark side of the rings. ISS has two prime observations, where the imaging team controls spacecraft pointing, on April 1 and 2. The first is a high-resolution radial scan from the F ring to the D ring, at high phase angles. The second is a medium resolution observation of the outer part of the B ring. To round out the rings observations, VIMS and ISS will observe the B ring on April 2 and 3 in order to search for spokes.
Cassini finishes up Rev63 with several observations of Saturnís small satellites, all designed to study their orbits. These observations include images of the outer satellite Ymir.
Cassini begins the following orbit, Rev64, on April 6.