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Cassini Significant Events 11/11/09 – 11/17/09

The most recent spacecraft telemetry was acquired on Nov. 17 from the Deep Space Network tracking complex at Canberra, Australia. 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: http://saturn.jpl.nasa.gov/mission/presentposition/ .

Wednesday, Nov. 11 (DOY 315)

Based on analysis of the preliminary data, the Navigation Team proposed the cancellation of Orbit Trim Maneuver (OTM) #222, planned to execute on Nov. 12. This was approved by the project. NAV also noted that it might be possible to cancel OTM-223. Cancellation was contingent upon an update to Enceladus pointing and agreement by the various instrument teams. Science Planning performed an OTM cancellation assessment based on a preliminary spacecraft ephemeris without the maneuver in it. The results are very clear: an unplanned Live Inertial Vector Propagator (IVP) update for Enceladus would need to be performed should both OTMs be canceled. The instrument teams completed their evaluation of the proposed pointing update to Enceladus and Rhea vectors on DOY 324-325 during the Enceladus 8 flyby period. The unplanned live update is a go, and OTM-223 has also been cancelled.

In addition to the Live IVP update mentioned above, Uplink Operations held a kickoff meeting for the Radio Science (RSS) Enceladus 8 Live Update Block (LUB) on DOY 324. RSS has evaluated the most recent data and no updates will be required to the product developed alongside the background sequence development in October. These files will be uplinked to the spacecraft on Nov. 18.

Thursday, Nov. 12 (DOY 316):

A news note on the Cassini Web page highlighted an image of the massive bright clouds of tiny ice particles hovering above the darkened rings of Saturn. The picture was taken on Sept. 22, around the time of Saturn's equinox, when the icy particle clouds appeared particularly dramatic because of the unique lighting geometry of the equinox period. These levitating icy particle clouds, which are known as "spokes," have a radial extent of up to 10,000 kilometers. For the complete text of the feature link to:

Judges have selected the U.S. winners for the Cassini Scientist for a Day essay contest. Details on the contest, selected essays, and images can be found at:

Friday, Nov. 13 (DOY 317):

Science and engineering teams delivered files for the third and final input port for the S58 Science Operations Plan process. The files have been merged and released for review. The process concludes Nov. 30 with the final development process ­ the Science and Sequence Update Process ­ beginning the following week. S58 execution begins March 1, 2010.

The S54 sequence concluded and S55 began execution today at 2009-315T12:44 PST. The sequence will run for 39 days and conclude on Dec. 22. During that time there will be two targeted encounters, one of Enceladus and one of Titan, and six non-targeted flybys ­ one each of Helene, Pandora, Titan, Calypso, Rhea and Pallene. Six maneuvers are scheduled, numbered 223 through 228.

Science at the start of S55 included observations for an Optical Remote Sensing Titan cloud monitoring campaign. Imaging Science then observed the dark-side of Saturn in search of lightning, obtained images of the transits of Titan across Hyperion and Enceladus across Rhea for orbit determination purposes, conducted Saturn wide angle camera photopolarimetry observations, and imaged a couple of stars as part of a charge transfer calibration. Magnetospheric and Plasma Science (MAPS) instruments continued with the solar wind-aurora campaign, and began a magnetospheric boundaries campaign. The Ultraviolet Imaging Spectrograph performed observations as part of a large campaign to measure Saturn¹s magnetosphere at apoapsis, and took a distant look at Enceladus to map volatiles in the immediate neighborhood. These observations will test the connection of volatile changes to plume eruptions.

Tuesday, Nov. 17 (DOY 321)

An encounter strategy meeting was held today to cover the period between Nov. 21 and Dec. 12, Enceladus flyby E8 and Titan flyby T63, and maneuvers 224 - 226. Navigation has determined that maneuver #224 is a good candidate for early uplink. After examining the schedule, it appears that there are two DSN passes early Saturday morning after the main engine cover is reopened that would work.