Cassini is orbiting Saturn with a 35.8-day period in a plane inclined 40.7 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on May 14 using one of the 34-meter diameter Deep Space Network stations at Goldstone, California. Except for the science instrument issues described in previous reports (for more information search the Cassini website for "CAPS" and "USO"), the spacecraft continues to be in an excellent state of health with all of its subsystems operating normally. Information on the present position of the Cassini spacecraft may be found on "Eyes on the Solar System".
While Cassini spent the week speeding in towards Saturn for a May 16 periapsis passage, its activities were controlled by the onboard S83 command sequence. On the ground, Sequence Implementation Process teams made progress on the 10-week command sequences S84, S85, and S86. The Radio Science team continued to lead preparations for a realtime occultation experiment and a bi-static observation planned to execute during the May 17 Titan T-101 encounter. The Navigation team continued to work on Cassini's orbital path and upcoming opportunities for Orbit Trim Maneuvers, and planning proceeded for the 2016 start of the F-ring and Proximal Orbits mission phase.
Wednesday, May 7 (DOY 127)
The Magnetospheric Imaging Instrument (MIMI) completed a 37-hour solar wind observation. The Imaging Science Subsystem (ISS), the Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS) then performed a 1.5-hour observation in the Titan monitoring campaign at a distance of 1.8 million kilometers from the giant haze-enshrouded moon. Next, ISS spent one hour looking for small objects near Saturn as part of the satellite orbit campaign, with VIMS also taking data as a ride-along participant. When this was done, VIMS squeezed in a two-minute Saturn storm-watch observation. Finally, ISS led CIRS and VIMS in an 18-hour observation of a faint ring arc while it was illuminated at low phase.
The flight team used a Deep Space Network station in California to uplink a new version of software for the CIRS instrument. After a round-trip light-time of 2 hours 28 minutes, telemetry showed that each one of the 2,416 individual commands had been properly received and stored onboard.
Thursday, May 8 (DOY 128)
VIMS spent eight hours creating a mosaic of the sunlit side of the rings, while CIRS and ISS rode along.
Friday, May 9 (DOY 129)
The Ultraviolet Imaging Spectrograph (UVIS) began a 29-hour observation of Saturn’s northern aurora with CIRS, ISS, and VIMS taking data as well.
Saturday, May 10 (DOY 130)
Cassini's Navigation team used ISS for 1.5 hours to take some images of Saturn's satellite Mimas against the background of stars for optical navigation purposes. ISS then carried out a color scan of the sunlit side of the main rings; this took five hours to complete, while CIRS and VIMS also took data in ride-along mode.
Saturn rose at sunset tonight; it's at opposition in Earth's sky. Excellent viewing opportunities continue during the coming months for anyone with a small telescope. A first view of Saturn is always a memorable experience. This and more are featured in JPL's "What's Up" video for this month: https://www.jpl.nasa.gov/video/details.php?id=1297
Sunday, May 11 (DOY 131)
UVIS made a seven-hour observation of Saturn's moon Tethys with ISS and VIMS riding along. Next, VIMS did a quick Saturn storm-watch observation, and then UVIS captured a two-hour observation of the moon Enceladus with ISS riding.
Monday, May 12 (DOY 132)
UVIS observed Saturn’s thermosphere for thirteen hours to refine knowledge of the density of Saturn's upper atmosphere. This will be of particular use in planning the 2017 proximal orbit mission segment.
Radial "spoke" structures in Saturn's rings are by nature very short-lived. An image featured today captured spokes in the B ring before they dispersed, which happens because each ringlet has a different orbit period, causing an effect called Keplerian shear:
Tuesday, May 13 (DOY 133)
UVIS conducted an observation of Saturn's south polar auroral region with CIRS and VIMS riding along.