Cassini Significant Events for 11/22/06 - 11/29/06

Cassini Significant Events for 11/22/06 - 11/29/06

The most recent spacecraft telemetry was acquired Wednesday, November 29, from the Goldstone tracking stations. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the “Present Position” web page located at .

Wednesday, November 22 (DOY 326):

The December issue of National Geographic Magazine, which is on newsstands now, features the Cassini-Huygens mission in a 20-page article.

To preview visit:

Also in this issue is a pullout poster of the planets, available as an interactive feature at:

Thursday, November 23 (DOY 327):

JPL Holiday

Friday, November 24 (DOY 328):

JPL Holiday

The S25 sequence concluded and S26 began execution today at 2006-328T16:30:00. The sequence will run for 42 days and conclude on January 5, 2007. During that time there will be two targeted encounters of Titan and three non-targeted flybys - two of Titan and one of Telesto. Seven OTMs are scheduled, numbered 81 through 87.

Today RPWS wrapped up a 2.5-day campaign to monitor the solar wind. This study needed to be performed while Cassini was well upstream of Saturn’s bow shock in careful coordination with Earth based observations of Saturn’s aurora.

A Science Allocation Plan (SAP) mini-sequence for the Radio and Plasma Wave Science instrument was uplinked to the spacecraft today. The mini-sequence will run from DOY 330-335.

Saturday, November 25 (DOY 329):

A non-targeted flyby of Titan occurred today at an altitude of 925,150 km. During this flyby, RADAR obtained distant Titan observations in preparation for T21. The distant Titan radiometer scans provide data to help remove the effect of spillover sidelobes in the Synthetic Aperture RADAR (SAR) radiometry data. This greatly enhances the value of radiometry data obtained coincident with the SAR image.

Sunday, November 26 (DOY 330):

The Solid State Power Switch (SSPS) on the Reaction Wheel Assembly (RWA) #4, line #1, unexpectedly changed state from ON to tripped at 329T18:35:06 SCET today. There was no impact to spacecraft performance, as there are two power lines per RWA and a single line is capable of carrying the entire load. The tripped switch was brought back on-line by a command from the ground. This was done using a new on-the-shelf “Tripped RWA SSPS” procedure developed after the last such trip on November 3, 2005. The spacecraft is operating normally following this activity.

These SSPS trips have been seen before and are most likely caused by Galactic Cosmic Rays. So far there have been 20 such trips since launch, and they are predicted to occur at a rate of about two per year. This is the first time an SSPS tripped that had tripped in the past. The SSPS for RWA-4 line 1 previously tripped on Nov. 3, 2005. Interestingly, the last five trips, since May 1, 2006, have occurred about 7-8 weeks apart.

Monday, November 27 (DOY 331):

Orbit Trim Maneuver (OTM) #81, an apoapsis maneuver, was performed today. This was the first time in the mission where an OTM executed over the backup opportunity was significantly smaller than it would have been if executed during the prime opportunity. The difference was 0.2 m/sec vs. 0.75 m/sec. The reaction control subsystem burn began at 6:29 AM PST. Telemetry immediately after the maneuver showed a burn duration of 160.1 seconds, giving a delta-V of 0.22 m/s. All subsystems reported nominal performance after the maneuver.

A beautiful image of the spokes in the rings of Saturn is Astronomy Picture of the Day today.

Tuesday, November 28 (DOY 332):

Today the Imaging Science Subsystem and the Ultraviolet Imaging Spectrograph performed a synergistic radial scan following the shadow boundary on the main Rings. Performing this type of observation at this specific geometry will help identify inclined rings.

The S28 kick-off meeting was held today as part of the final sequence development process. The flight team has been considering for some time how to streamline the overall development process consisting of the Aftermarket Process, Science Operations Plan Update Process (SOPU), and the final piece, the Science and Sequence Update Process (SSUP). As a result, the SOPU final meeting and presentation to Program Management has been combined with the SSUP kick-off meeting. The combining of these two meetings has proved to be a significant time saver for members of Science Planning and Uplink Operations.

At the Mission Planning Forum today, DSN personnel presented the results of a study, performed at the request of Mission Planning, to determine possible DSN resource conflicts - due to competition with other missions and antenna down times - during extended mission. This was followed by a discussion on how best to plan around the conflicts.

The Cassini-Huygens Analysis and Results of the Mission (CHARM) teleconference for November was held today. The topic addressed a new perspective on the rings of Saturn as well as recent results on the faint rings.

A member of the Cassini Mission Support & Services Office (MSSO) gave a presentation on Cassini to 60 students from three third grade classes at Mayfield Junior School in Pasadena, CA today. The students and teachers received outreach material and created Saturn books using Cassini’s K-4 literacy program, Reading, Writing and Rings. Lesson 9, “Focus on Saturn’s Fascinating Features”, is a great activity for informal as well as formal education audiences. Here is a link to some of the program activities:

Wrap up:

Check out the Cassini web site at for the latest press releases and images.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Spsce Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter.