Cassini Significant Events 10/19/06 - 10/25/06

October 27, 2006

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired on Wednesday, Oct. 25, from the Madrid 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, Oct. 19 (DOY 292):

An Encounter Strategy Meeting was held today for the maneuvers to occur between Titan 20 and Titan 21. This will be for OTMs 80 through 82, and for the period from Oct. 25 through Dec. 12.

Friday, Oct. 20 (DOY 293):

Today was the last day of the 40th Cassini Project Science Group meeting. Science investigators and other participants came to JPL for this week-long discussion of science results and future planning. One of the most significant items on the agenda was the selection of final tour candidates for Extended Mission.

The S25 background sequence was uplinked today at 293T11:39:35. The sequence programs have been registered and activated. Execution will begin this Sunday.

Orbit Trim Maneuver (OTM) #79 was performed on Sunday, Oct. 22. This is the approach maneuver setting up for the Titan 20 encounter on Wednesday. The reaction control subsystem burn began at 9:45AM PDT. Telemetry obtained after the maneuver showed the burn duration was 44.25 seconds, giving a delta-V of 0.063 m/s. All subsystems reported nominal performance after the maneuver.

Sunday, Oct. 22 (DOY 295):

The keys to the spacecraft were handed over to the leads of the S25 sequence today. S25 began execution at 2006-295T18:26:00 Spacecraft Event Time. The sequence will run for 33 days, concluding on Nov. 24. During that time there will be one Titan targeted encounter, non-targeted encounters with Telesto, Enceladus, Calypso, and Dione, and OTM-80 is planned to execute. On the science side, the S25 sequence kicked off with an Ultraviolet Imaging Spectrograph observation of Dione while the Magnetospheric and Plasma Science instruments carried out a study of Saturn's magnetotail. The magnetotail is the long anti-sunward extension of the magnetosphere.

Wednesday, Oct. 25 (DOY 298):

The first meeting of the Extended Mission (XM) Integration Guidelines and Constraints Working Group was held today. The charter of this group is to develop the XM integration Guidelines and Constraints document to be used by the Target Working Teams and Orbiter Science Teams to integrate the activities in extended mission. Meetings are scheduled to occur semi-monthly.

STEREO launched successfully today from Cape Canaveral Air Force Base. Like Cassini this was a night launch with a launch time of 8:52 EST. The successful launch removed possible DSN conflicts on DOY 310 & 314 during the 48-hour launch contingency period.

The Titan 20 flyby occurred today with closest approach at an altitude of 1030 km and eight degrees latitude. For this flyby, the main objective of the Visual and Infrared Mapping Spectrometer (VIMS) was to acquire high spatial resolution images of Titan's surface in order to characterize the different units that have been discovered by either VIMS or RADAR. These observations are considered to be some of the most critical for VIMS in the prime mission.

The low altitude of the T20 flyby made it possible to study the wake, tail formation, and Saturn facing flank region, where the magnetic field topology may be particularly complex. The Magnetometer team took advantage of this very close approach which makes this orbit particularly useful for studies of an internal magnetic field.

Radio and Plasma Wave Science (RPWS) measured the thermal plasma properties of Titan's ionosphere, including the electron density and pressure, as well as characterizing the interaction of Saturn's magnetosphere with Titan.

The Magnetospheric Imaging Instrument (MIMI) utilized T20's good orientation to characterize the plasma flow, and to sample field-aligned energetic ions and electrons. Titan, or at least part of Titan, will remain within the Ion and Neutral Camera field of view throughout the close encounter, so MIMI should be able to image the energetic ion/exosphere interaction though a large range of geometries.

Finally, RADAR will put together a radiometry map of northern Xanadu and terrain up to 70 deg N latitude.

The accelerometer (ACC) part of the Attitude and Articulation Control Subsystem (AACS) was powered on for the T-20 encounter in order to have an additional independent method to estimate the atmospheric density of Titan. The team was able to capitalize on the spacecraft orientation during this flyby. The aerodynamic forces and the reaction force due to the firing of the z-facing thrusters would be pushing the spacecraft in the same direction. Due to the combined effects of these two forces, it is expected that the AAC data will show counts between 50 and 100. Further status on this activity will be reported next week.

The JPL Stories program, sponsored by the Library, Archives, and Records Section, celebrates the Lab's unique environment and history, and provides an informal way for JPLers to share their stories with each other. This week, the Cassini Virtual Singers presented "The History of Cassini-Huygens in Song and Verse." This group of singers, non-singers, and those who want to join in are all members of the Cassini Flight Team. The program was a lighthearted look at the project from ATLO to launch, flybys to SOI -- as memorialized in songs written by none other than the Cassini Virtual Singers!

The Cassini project has released a dramatic portrait of the Saturnian moon Janus against the backdrop of Saturn. To view the image and the full text description link to:

The Cassini Project has recently begun to produce video logs featuring various members of the flight team who describe highlights of their areas of involvement on the project as well as a brief description of what happened with the last Titan flyby and what's in store for the upcoming one. The plan is to produce one such product between each pair of Titan encounters. Three are now available and can be viewed at Select from one of the four download options to view the video.