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Cassini Significant Events 09/24/2014 - 09/30/2014 Cassini is orbiting Saturn with a 31.9-day period in a plane inclined 40.3 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were obtained on Sept. 30 using one of the 34-meter diameter Deep
Space Network (DSN) 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. Information on the present position of the Cassini spacecraft may be found on "Eyes
on the Solar System." This was the last full week for the S85 command sequence to direct Cassini's activities. The next sequence, S86, was approved Monday for uplink, and it will take control of the spacecraft early next week. Meanwhile, Cassini's sequence implementation
teams worked on developing the 10-week spacecraft command sequences S87 and S88. Wednesday, Sept. 24 (DOY 267) As Saturn's planet-like moon Titan continued to recede following last Sunday's close flyby, the Imaging Science Subsystem (ISS) controlled spacecraft pointing to keep all of Cassini's telescopes tracking it, studying its clouds and surface
features for almost the entire day. Along with ISS, the Visible and Infrared Mapping Spectrometer (VIMS), the Composite Infrared Spectrometer (CIRS), and the Ultraviolet Imaging Spectrograph (UVIS) all acquired data while trained on Titan. During today's DSN support, the flight team uplinked commands that will support instrument operations once the S86 sequence begins executing next week. In all, 3,155 individual Instrument-Expanded Block (IEB) commands were transmitted.
After a round-trip light time of 2 hours 56 minutes, telemetry showed that they had been properly received. Thursday, Sept. 25 (DOY 268) The flight team prepared commands to turn the spacecraft and fire its small rocket thrusters for 63 seconds, and uplinked them today using a 34-meter diameter DSN station in Australia. This comprised Orbit Trim Maneuver 392, the post-Titan
T-105 trajectory cleanup maneuver. It imparted the desired change in velocity of 66 millimeters per second to the 2,253-kilogram spacecraft. Even though the T-105 flyby was extremely accurate with a less than 200-meter error, these small cleanups are used to properly distribute the desired trajectory changes between the points near the encounter and the (usually) larger maneuvers
near apoapsis. Friday, Sept. 26 (DOY 269) ISS tracked Saturn's F ring for 15 hours today to create a low-resolution movie; this period allowed coverage of one complete revolution of the ring's particles about Saturn. CIRS and VIMS rode along, taking data. During the DSN pass that
followed, the remaining 2,060 individual IEB commands were uplinked and then later confirmed on board. Saturday, Sept. 27 (DOY 270) The Cosmic Dust Analyzer (CDA) directed spacecraft pointing for sixteen hours today to observe exogenous dust — particles that originate outside the Saturn system. Sunday, Sept. 28 (DOY 271) ISS spent 15 hours observing Saturn's irregular moon Ijiraq. This cold, very dark-surfaced object, about 10 kilometers in diameter, orbits Saturn in a highly inclined, highly elliptical orbit that reaches more than eleven million kilometers
from the planet. It was named after the shadowy creature of Inuit legend. Monday, Sept. 29 (DOY 272) CDA began a 36.5-hour-long observation of exogenous dust. Cassini has shown that Titan's surface and its dense atmosphere are always changing. A news feature released today describes an as-yet unexplained phenomenon in the great lake on Titan known as Ligeia Mare. An image featured today shows off Saturn's beautiful cloud patterns, which are shaped by high-speed winds:
http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=5097 Tuesday, Sept. 30 (DOY 273) This week, the DSN communicated with and tracked Cassini on five occasions, using stations in Australia and California. A total of 5,502 individual commands were uplinked, and about 1,570 megabytes of telemetry data were downlinked at rates
as high as 142,201 bits per second. For a glossary of technical terms relating to these events, click the "full story" link on this page:
http://saturn.jpl.nasa.gov/news/significantevents.
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