Cassini Significant Events 09/10/08 - 09/16/08

September 18, 2008

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired on Sept. 16 from the Deep Space Network tracking complex at Goldstone, California. The Cassini spacecraft is in an excellent state of health and all subsystems are operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the "Present Position" page at:

Wednesday, Sept. 10 (DOY 254):

Science activities today began with the Cassini Plasma Spectrometer (CAPS) leading a Magnetospheric and Plasma Science (MAPS) auroral investigation. After turning to Earth and downlinking this data, the spacecraft stayed Earth pointed as the rings of Saturn passed between Earth and the spacecraft. This provided an opportunity for a Radio Science (RSS) ring occultation experiment. Cassini used its radio transmitter to send multiple frequency radio signals through the rings. Scientists carefully monitor the signals as they are received on Earth. This allows them to deduce the structure and composition of the rings. The day ended with a joint Optical Remote Sensing (ORS) campaign of Saturn's south polar region.

A non-targeted flyby of Epimetheus occurred today.

Science Planning, Composite Infrared Spectrometer (CIRS), Imaging Science (ISS), Ultraviolet Imaging Spectrograph (UVIS), and Visual and Infrared Mapping Spectrometer (VIMS) teams weighed in today at the Go/No Go meeting for the first S44 Live IVP Update. It's a go for updates to Saturn, Cassini, and Enceladus vectors to execute on DOY 161. Uplink of the necessary files is planned for next Monday.

The Cassini Radio Science (RSS) S43 orbit 84 rings chord occultation was completed on Wednesday, Sept. 10. The experiment was covered by Madrid's DSS-63 station with X- and S-band support, and DSS-54 with X- and Ka-band support. This was the last in a family of four fast chord occultations that probed the rings when the opening angle was small, about 5 to 7 degrees. This was also the first time DSS-54 provided RSS occultation experiment support. DSS-55 at Madrid is usually scheduled to support the RSS Ka-band activities, but since that antenna is currently down for upgrades and maintenance, DSS-54 was scheduled instead.

A nice image of the Anthe ring arc around Saturn was Astronomy Picture of the Day today. The image may be seen at:

Thursday, Sept. 11 (DOY 255):

Sequence Team leads uplinked the S44 background sequence today. In addition, a CIRS noise test and flight software patches to instrument FSW version 5.0.4 were also uplinked. The patches will be used to determine the best way to remove certain types of noise from the CIRS science data. Following the results of the noise tests, a permanent patch to the CIRS FSW will be made. The permanent patch will decrease the odds of the CIRS scan mechanism becoming stuck by increasing a timing constraint the software uses in controlling the mechanism. The current CIRS commands will execute on DOY 259.

Saturday, Sept. 13 (DOY 257):

Science activities at the end of S43 included a continuation of an orbit determination study performed by ISS on some of the lesser-known Saturnian satellites. Next, UVIS, CIRS, and ISS observed Saturn's moon Rhea for six and a half hours to look for trace volatile elements. This was followed by ISS images of the G-Ring arc and an opportunistic "mutual event" image of Dione transiting across Enceladus. Finally, CAPS led another MAPS survey of the magnetic and plasma environment of Saturn.

The S43 sequence concluded and S44 began execution today at 2008-257T23:44 SCET. The sequence will run for 35 days and conclude on Oct. 18. During that time there will be a targeted encounter of Enceladus and fifteen non-targeted flybys -- two each of Titan, Tethys, and Pallene, and one each of Pandora, Mimas, Calypso, Daphnis, Atlas, Pan, Telesto, Janus, and Epimetheus. Five maneuvers are scheduled, numbered 164A, and 165 through 168,

Monday, Sept. 15 (DOY 259):

A presentation on "Missing Noble Gases from the Titan Atmosphere" was given today at JPL. The noble gases are a group of chemical elements with very similar properties; under standard conditions, they are all odorless, colorless, monatomic gases, with a very low chemical reactivity. The six noble gases that occur naturally are helium, neon, argon, krypton, xenon, and the radioactive radon. The melting and boiling points for each noble gas are close together, differing by less than 10 degrees Celsius; consequently, they are liquids only over a small temperature range.

Sequence leads sent commands to the spacecraft today for a Cosmic Dust Analyzer (CDA) ring plane crossing activity and a noise test, and for the S44 Live Inertial Vector Propagator (IVP) Update #1. All files have properly registered on-board the spacecraft.

Tuesday, Sept. 16 (DOY 260):

A non-targeted flyby of Titan occurred today.

The S46 Science Operations Plan product was handed off to the Sequence Team today and the final sequence development process for S46, the Science and Sequence Update Process, began. Items still to be closed are RADAR requests for testing of the T48 and T49 Titan flybys in the Integrated Test Laboratory, and establishing a schedule and resources for the three Live IVP updates scheduled in S46.

Today a talk was presented on "Saturn's moon Titan: View from Cassini's RADAR Mapper." Case studies using Synthetic Aperture Radar (SAR) and high-resolution radiometry data for geological mapping and characterization of Titan's surface were presented. Emphasis was on flows and drainage patterns, geology, crater structures, dunes, lakes, and evidence of structural control on drainage and flow features in the Hotei area. Suggestions were also presented on opportunities for data synergy between SAR/high-resolution radiometry/VIMS for geological mapping and SAR/altimetry/VIMS for surface and subsurface studies.