Cassini Significant Events -- 10/06/05 - 10/12/05

October 14, 2005

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired Wednesday, October 12, from the Goldstone tracking complex. The Cassini spacecraft is in an excellent state of health and all subsystems are operating normally. Check out the Cassini web site at for the latest press releases and images.

Thursday, October 6 (DOY 279):
The Project gave approval for the cancellation of Orbit Trim Maneuver (OTM) #37. The decision was arrived at after it was determined that not performing OTM-37 had minimal navigational impact, no measurable science impact at Dione, and only a minimal impact at Telesto. A live Inertial Vector Propagator (IVP) update for one vector will be uplinked Sunday to modify pointing for Telesto. A Reaction Wheel Assembly bias will be performed during the prime OTM-37 pass on Saturday.

Cassini's second archive delivery milestone scheduled for October 1, and containing data from October of 2004 through December of 2004, is 99% complete.

Commanding today included uplink of the S15 background sequence, the Composite Infrared Spectrometer (CIRS) flight software checkout mini-sequence, and a Magnetospheric Imaging Instrument (MIMI) coincidence plate parameter update that will lower high voltage for safety during the ring plane crossing period.

Saturday, October 8 (DOY 281):
The S14 background sequence concluded today. S15 began execution at 6:49 AM Pacific Time. The sequence will run for 35 days, concluding on November 12. Events during this time include targeted flybys of Dione on October 12 and Titan on October 28, non-targeted flybys of Telesto, Pallene, Atlas, Enceladus, Methone, and Calypso, and OTMs 38 through 41. During this sequence the RADAR instrument will obtain synthetic aperture radar coverage of the Huygens probe-landing site as Cassini passes by Titan on October 28.

Sunday, October 9 (DOY 282):
The Main Engine cover was closed today for the ascending ring plane crossing as part of the E-ring dust hazard avoidance procedure. The cover will be opened Tuesday for OTM-38, and then closed again for a short period of time while Cassini descends through the ring plane. The cover will then be opened and remains open until mid-May.

The sequence leads uplinked files to the spacecraft today for the RADAR Dione trigger and Telesto Live IVP Update. Files will execute on Tuesday.

Monday, October 10 (DOY 283):

A picture of Saturn's storms taken by Cassini is Astronomy Picture of the Day today.

Tuesday, October 11 (DOY 284):
Today Cassini continued an amazing string of close icy satellite encounters with the targeted encounter at Dione. Closest approach occurred on Tuesday, October 11th, at 12:10 PM Pacific Time at an altitude of 500 km above the surface and at a speed of 9 kilometers per second. Dione has a diameter of 1120 km, making it the third-largest icy satellite after Iapetus and Rhea.

The encounter itself occurs very near Saturn periapsis. The cleanup maneuver for the flyby contains a large deterministic component that is important for targeting for future encounters and occurs less than a day after the encounter.

The flyby geometry of Dione is oriented such that her wispy terrain is easily observable by the remote sensing instruments on Cassini. The primary science investigations will be centered on the following questions: What is the compositional makeup of Dione, other than water ice? Did resurfacing occur early in Dione's history? What do the cracks and fractures tell us about the recent geologic history of Dione? How does Dione interact with Saturn's rings and magnetosphere?

Non-targeted flybys of Telesto, Pallene, Atlas, and Enceladus occurred today as Cassini was departing Dione.

Wednesday, October 12 (DOY 285):

An image of the cliffs and craters on Tethys is Astronomy Picture of the Day today.
OTM-38 was successfully completed today. Also known as the "D1+1 day" maneuver, this is a clean-up maneuver following Cassini's flyby of Dione. This OTM occurred near Saturn periapsis, and was bracketed by ascending and descending hazardous ring plane crossings. The main engine burn began at 12:15 am PST, with a duration of 92.7 seconds, giving a delta-V of approximately 14.8 m/s. All subsystems reported nominal performance after the maneuver.

A delivery coordination meeting was held today for version 11.1 of Kinematic Prediction Tool (KPT).