News | July 16, 2014
Cassini Significant Events 07/09/2014 - 07/15/2014
Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 46.5 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on July 16 using the 70-meter diameter Deep Space Network (DSN) station at Canberra, Australia. The spacecraft continues to be in an excellent state of health with all of its subsystems operating normally except for the instrument issues described at http://saturn.jpl.nasa.gov/news/significantevents/anomalies. Information on the present position of the Cassini spacecraft may be found on "Eyes on the Solar System".
Continuing to fall inward from last week's apoapsis, Cassini more than doubled its speed this week, reaching 23,000 kilometers per hour relative to the planet by Tuesday. Meanwhile, the usual targets -- Saturn, its rings, its satellites, and its magnetosphere -- were subject to Cassini's scientific observations.
Wednesday, July 9 (DOY 190)
Though not often recounted in these reports, Cassini's science teams frequently put their instruments through calibration exercises to ensure that the scientific data return can be accurately validated. Today the Magnetometer went through a routine calibration by rotating the spacecraft slowly about its X-axis for 10.5 hours.
Thursday, July 10 (DOY 191)
The Composite Infrared Spectrometer (CIRS) targeted Titan for 13 hours to perform a special calibration in support of the Herschel Space Observatory, which has also studied Titan's complex atmosphere. CIRS used instrument modes that would be helpful to the Herschel team. Once the calibration was complete, CIRS began a 13.5-hour Titan observation of its own, as part of the campaign to study Titan's atmospheric composition. A similar observation lasting 37 hours started on Friday.
Friday, July 11 (DOY 192)
The DSN carried out two-way digital communications and radiometric tracking with Cassini on five occasions this week, using stations located in Australia.
Sunday, July 13 (DOY 194)
When CIRS relinquished control of spacecraft pointing, the Imaging Science Subsystem (ISS) took over to make an observation in the satellite orbit campaign, looking at objects near Saturn. The Visible and Infrared Mapping Spectrometer (VIMS) also took data. Then, since pointing was already close to Saturn, ISS and VIMS made a two-minute storm-watch observation on the planet. Next, the Ultraviolet Imaging Spectrograph (UVIS) turned to observe the leading hemisphere of Saturn's satellite Dione for just over nine hours, mapping its albedo in the ultraviolet. ISS and VIMS rode along taking data as well. As soon as that observation was finished, ISS and VIMS made another two-minute Saturn storm watch observation. Just before day's end, UVIS started a two-hour observation of Enceladus’ leading hemisphere, again measuring the ultraviolet albedo.
Monday, July 14 (DOY 195)
ISS watched Saturn's moon Tethys as it transited across the smaller, more distant moon Hyperion. These images will provide data for JPL experts who refine knowledge of the ephemeris of natural bodies. VIMS rode along. ISS and VIMS then observed the faint rings while they were sunlit at low-phase and low elevation for 4.5 hours, and then both instruments watched the D ring for four hours to create a close-in movie of the D ring. Plans are for Cassini to explore the region interior to this innermost of Saturn's rings in a few years. Finally, ISS and VIMS again took advantage of the pointing and slewed over to the planet for a quick storm watch.
Saturn's satellite Prometheus, which is 136 kilometers long and 60 to 80 kilometers wide, orbits inside of the F ring, where it completes one revolution about the giant planet every 14 hours 38 minutes. An image featured today shows it as a small dot amid the expansive ring system: /resources/16058
Tuesday, July 15 (DOY 196)
UVIS observed Saturn’s northern aurora for 13.5 hours. This observation was one in a campaign coordinated with the Hubble Space Telescope and the Keck Observatory in Hawaii, timed around Saturn opposition and solar maximum. When it was done, ISS executed another two-minute storm watch, this time without VIMS.