Cassini Significant Events 07/29/15 – 08/04/15

Cassini is currently orbiting Saturn with a period of 21.8 days in a plane inclined 0.5 degree from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on Aug. 4 using one of the 34-meter diameter Deep Space Network stations in California. 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 .

Cassini's activities this week were orchestrated by timed commands from the on-board, 10-week-long S90 sequence, which took control on July 13. Meanwhile, the Sequence Implementation Process teams worked on creating the sequences S91, S92 and S93. The latter is planned to go active on the spacecraft this February. Plans proceeded as well for Cassini's F-ring and Proximal orbits and Grand Finale in 2016 and 2017.

Wednesday, July 29 (DOY 210)

Cassini's Imaging Science Subsystem (ISS) carried out a two-minute storm-watch observation on Saturn, with the Visible and Infrared Mapping Spectrometer (VIMS) participating. This observation was repeated on Friday, and then again on Saturday without VIMS. Following today's, ISS and the Ultraviolet Imaging Spectrograph (UVIS) turned the spacecraft and tracked Saturn's small active moon Enceladus for 13 hours to observe the variability of its icy south-polar plumes, while they were back-lit by the Sun.

The Cosmic Dust Analyzer (CDA) took advantage of Cassini's proximity to the orbit of Saturn's moon Hyperion. The instrument sampled dust that likely originated from that moon, which has a sponge-like appearance. Next it turned to capture dust orbiting in the vicinity of Saturn's largest moon, Titan. CDA's observations today lasted 19.5 hours, and were part of a ring-search campaign.

A news feature released today relates Cassini's discovery of unusual arcs on Saturn's moon Tethys, not readily apparent in visible light, but which show up as red when viewed using ISS's various color filters: http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20150729 .

Thursday, July 30 (DOY 211)

When CDA finished its ring-search surveys, Cassini turned to face its high-gain antenna toward Earth for a typical session with the Deep Space Network (DSN). After propagating 79.5 minutes at the speed of light, Cassini's continuous radio signal reached Earth. Right on time, the 70-meter diameter DSN antenna in Spain finished turning its six-million-pound dish towards Saturn, which was rising in the east. Cassini and the DSN then continued tracking each other across the distance for the rest of the day, accomplishing a total of 8.5 hours of flawless two-way digital communications and radiometric tracking.

Friday, July 31 (DOY 212)

VIMS began a 24-hour-long observation of Saturn's E ring, which encompasses Enceladus's orbit about Saturn, and also made observations of the faint G ring. Both were sunlit at 130 degrees phase angle. ISS and the Composite Infrared Spectrometer (CIRS) also observed. ISS's views of the E ring are often remarkable; they may be found by searching on the Raw Images web page: http://saturn.jpl.nasa.gov/photos/raw .

Saturday, Aug. 1 (DOY 213)

Cassini's navigation team used ISS for 90 minutes today to acquire images of Hyperion against the background stars. When this was done, UVIS took over pointing for 75 minutes to create a radial profile of Saturn’s atmosphere.

Sunday, Aug. 2 (DOY 214)

Cassini’s Magnetospheric Imaging Instrument (MIMI) began a 38-hour observation to study Saturn’s magnetosphere. Late in the day during 14 hours of MIMI's long observation, CIRS mapped Saturn’s atmosphere in the mid-infrared part of the spectrum, collecting data on temperatures in the troposphere and tropopause.

Monday, Aug. 3 (DOY 215)

CIRS took control of the spacecraft's attitude for nearly 21 hours for a "COMPSIT" observation wherein the instrument's field of view sits on one spot on Saturn. The objective is to collect high-quality infrared spectra to determine the atmosphere's composition. This coincided with a 20-hour MIMI observation of the planet's magnetosphere.

An eerie shot of two moons, with a giant looming behind them, was featured today:
/resources/16220 .

Tuesday, Aug. 4 (DOY 216)

During the past week, the DSN communicated with and tracked Cassini on four routine occasions, using deep space stations in Spain and California. A total of 10 individual commands were uplinked, and about 1,179 megabytes of telemetry data were downlinked and captured at rates as high as 142,201 bits per second.

This illustration shows Cassini's position on Aug. 4: https://space.jpl.nasa.gov/cgi-bin/wspace?tbody=-82&vbody=1001&month=8&day=4&year=2015&hour=23&minute=55&fovmul=1&rfov=40&bfov=30&brite=1&showsc=1&showac=1 .