Cassini Significant Events for 06/29/06 - 07/05/06

Cassini Significant Events for 06/29/06 - 07/05/06

The most recent spacecraft telemetry was acquired on Wednesday, July 5, from the Goldstone tracking complex. 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” web page at .

Thursday, June 29 (180):

Thursday, June 29, found Cassini three days away from the Titan 15 (T15) encounter. The Cosmic Dust Analyzer (CDA), one of the six Magnetospheric and Plasma Science (MAPS) instruments, began the day by scanning for E ring particles. After this, the Imaging Science Subsystem (ISS) continued its observations of Hyperion. The day concluded with more CDA scans of the E Ring, and a Visual and Infrared Mapping Spectrometer (VIMS) Saturn “Feature Track” observation.

Commands were included in the S21 background sequence to close the Main Engine (ME) cover today in order to avoid possible dust hazards prior to the Titan-15 encounter. The ME cover has now been cycled 30 times since launch. The cover will be opened this Saturday prior to the next Orbit Trim Maneuver (OTM) scheduled for Wednesday, July 5.

Uplink Operations sent commands to the spacecraft today for a Radar Instrument Expanded Block trigger for T15, and to patch Solid State Power Switch (SSPS) error monitor 127 back to zero. This patch is the final clean up for the trip that occurred last Wednesday, June 21, to the replacement heater for Stellar Reference Unit B.

Friday, June 30 (DOY 181):

Now two days away from the Titan 15 flyby, Radar is taking the opportunity to perform a distant Titan radiometry study, where the instrument is placed in a passive or “listen-only” mode, gathering energy from Titan. This observation also serves as a calibration opportunity or a precursor to the actual Titan science to come. After Radar completed its observation, VIMS observed a star emerging from behind Saturn. This type of occultation affords an opportunity to study Saturn’s atmosphere as light from the star passes through the various atmospheric layers near the limb of Saturn. Today ended with an ISS observation of newly discovered moons of Saturn, and a Composite Infrared Spectrometer (CIRS) observation of Enceladus and Saturn. For approximately 12 minutes, from 18:27 to 18:39 Spacecraft Event Time, Cassini was in the zone of possible Dione dust hazards, hence the closing of the ME cover yesterday.

A cloud of atomic oxygen Cassini encountered as it first approached Saturn in December of 2003 turned out to be a hint for a future significant discovery. The source of the oxygen would turn out to be the tiny moon Enceladus. For a description of how this all came about and for more information on Enceladus visit: or

Additional new updates to the Cassini website include an updated science section, information on the next Titan flyby, and status at the mission halfway mark. Here are some links to check out:

Cassini to Look In, Out and Over Titan New Updated Science Section: Saturn Rings Titan Moons Magnetosphere

Saturday, July 01 (DOY 182):

Today is the second anniversary of the Cassini Saturn Orbit Insertion.

Sunday, July 02 (DOY 183):

Today Cassini passed by Titan at an altitude of 1906 kilometers for the 16th targeted flyby of Titan since the start of tour. As the spacecraft approached, VIMS obtained data for a global map, CIRS measured trace constituents of CO, HCN, and CH4 in the Titan atmosphere, and ISS used the narrow angle camera to make a global map of Titan. Comparative data sets between VIMS and ISS will prove very useful for scientific analysis.

Five hours before closest approach, Radar was placed in a passive mode called Radiometry, receiving energy emanating from the surface of Titan. This will provide information regarding the moon’s surface properties. At 1 hour 15 minutes before closest approach, Radar was switched to active mode to perform Scatterometry measurements. Instead of creating Radar images, this mode of operation allows scientists to study the composition of Titan’s surface. These Radar Scatterometry measurements lasted 15 minutes, and then were followed by MAPS instrument observations for 90 minutes allowing in-situ measurements of Titan’s atmosphere and its interaction with Saturn’s magnetosphere.

For the outbound leg, CIRS performed vertical aerosol sounding of Titan’s stratosphere. This was followed by the Ultraviolet Imaging Spectrograph (UVIS) scans across Titan’s visible hemisphere and ISS night side search for and monitoring of lightning and aurora. The flyby concluded with CIRS measurements of trace constituents and thermal structure in Titan’s stratosphere.

Tuesday, July 04 (DOY 185):

In celebration of the holiday, nearly two hundred thousand parade watchers saw a Titan and Saturn “float” in the Plymouth, MA, Fourth of July parade. The float featured Saturn, Titan, Saturn Observation Campaign telescopes, Blake Planetarium information and much more.

The final sequence products for S22 have been published to the Cassini file repository. The spacecraft operations office has successfully tested all S22 SSR instrument expanded block loads (IEB). The final sequence approval meeting will be held on July 7, and the IEBs are scheduled for uplink beginning on July 11.

Today ISS took a series of images of a geometric event, the transit of one Saturnian moon across another. Two back-to-back crossings occurred, first Tethys across Janus, then Rhea across Enceladus. After a VIMS observation of the G ring, the day was concluded by placing the spacecraft in an 8-hour roll to perform a Magnetometer sensor calibration.

Wednesday, July 05 (DOY 186):

The Cassini Spacecraft and Saturn’s moons presentation was shown to 18 children at Donore Avenue Youth Centre in Dublin, Ireland, during their summer project activity week. After the Cassini presentation, the Irish Saturn Observation Campaign member showed “The Dream is Alive” Space Shuttle DVD to celebrate the Shuttle Launch on the Fourth of July.

OTM #65 was performed today. This is the cleanup maneuver from the T15 targeted flyby. The reaction control subsystem burn began at 4:00 PM PDT. Telemetry immediately after the maneuver showed the burn duration was 97 seconds, giving a delta-V of 0.14 m/s. All subsystems reported nominal performance after the maneuver.

NASA Cassini spacecraft images of Saturn’s diaphanous G and E rings are yielding new clues about their structure and formation. Images accompanying this release are available at

A Project Briefing for S24 was held today as part of the Science Operations Plan Update process.

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 Space 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.