NASA Cassini Significant Events 01/20/10 - 01/26/10

Status Report From: Jet Propulsion Laboratory
Posted: Friday, January 29, 2010

image The most recent spacecraft telemetry was acquired on Jan. 26 from the Deep Space Network tracking complex at Madrid, Spain. 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:

Wednesday, Jan. 20 (DOY 020)

Orbit Trim Maneuver (OTM) #234 was performed today. This was the apoapsis maneuver setting up for the Titan 66 encounter on Jan. 28. The main engine burn began at 9:59 PM PST. Telemetry immediately after the maneuver showed a burn duration of 35.53 seconds, giving a delta-V of 6.066 m/s. All subsystems reported nominal performance after the maneuver.

Thursday, Jan. 21 (DOY 021)

Over the last week, Uplink Operations coordinated the uplink of a Dione Live Inertial Vector Propagator update and a modification to a Radio Science (RSS) live movable block. Based on analysis and identification of only a small targeting error, Science Planning recommended a No-Go for the update. The Composite Infrared Spectrometer (CIRS), Imaging Science (ISS), Visual and Infrared Mapping Spectrometer (VIMS), and Ultraviolet Imaging Spectrograph (UVIS) agreed, so the update was cancelled. The "on the shelf" live movable block was determined to meet requirements and was uplinked today. It will execute on Jan. 26 during the RSS occultation experiments.

Friday, Jan. 22 (DOY 022)

The science at the end of S56 included an ISS observation of the atmosphere of Titan and satellite orbit determination observations. UVIS performed several magnetospheric scans, the Cassini Plasma Spectrometer (CAPS) took magnetospheric measurements, and CIRS performed measurements of Saturn's upper troposphere and tropopause temperatures with spatial resolution of about two degrees of latitude and longitude.

Saturday, Jan. 23 (DOY 023)

The S56 sequence concluded and S57 began execution today at 2010-023T15:00:00 SCET. The sequence will run for 37 days and conclude on March 1. During that time there will be one targeted encounter of Titan and eleven non-targeted flybys, one each of Telesto, Methone, Pan, Prometheus, Dione, Calypso, Epimetheus, Janus, Mimas, Tethys, and Titan. Four OTMs are scheduled, numbered 235 through 238.

At the top of S57 the Magnetometer performed an instrument calibration, ISS performed photometry of the rings from a low inclination, grazing geometry, and observed the plumes of Enceladus at high phase angles. VIMS pointed at Saturn's faint E and G rings for 11 hours to collect data at high signal-to-noise ratio. CIRS trained infrared sensors on Saturn's rings and was able to detect the polarization of infrared light emanating from the rings. Such observations are expected to yield information about the surfaces of ring particles. Finally, CAPS oriented the spacecraft to point itself and the other Magnetospheric and Plasma Science instruments to better study the dusk side of the magnetosphere of Saturn, and collected particles and fields data.

Monday, Jan. 25 (DOY 025):

Due to potential dust hazards, some precautionary measures are being taken on board the spacecraft this week. The Sun Sensor Assembly B was powered on, and the main engine cover closed. These will be set back to their normal states on Wednesday once the hazard has passed. The spacecraft will be oriented with its high-gain antenna pointed to the particle ram direction during the period of most concern.

The high flyby altitude at Titan 66 - 7,490 kilometers - coupled with the relatively small predicted target miss meant that cancelling OTM-235 would have no significant downstream delta-V costs. Science Planning and Radio Science analyzed the effect on their observations if OTM-235 was not performed. The deviations from the reference trajectory were found to be acceptable so the maneuver was cancelled.

A news note called "Groovy Hills Rising from Titan Surface" highlighted a new Radar image showing hills with a wrinkly radial pattern never before seen on the surface of Titan. The grooved mounds in the picture, which are located in a northern hemisphere region known as Belet, are about 80 kilometers wide and about 60 meters high. For the entire text link to:

Monday was a big day for sequence development milestones. A kick-off meeting was held for the S59 Science and Sequence Update Process, the final process in sequence development, and S61 held a Science Forum where all high value science and science activities in the sequence are outlined to the other instrument teams. The Spacecraft Office and Target Working Team (TWT)/ Orbiter Science Team (OST) integrated products for S62 covering orbits 135 through 137 were delivered. The integrated products are in their final form and no re-integration is planned. The next step in sequence development, Science Operations Plan (SOP) implementation, will kick off on Feb. 8. Between now and the kickoff, the instrument teams will be working on pointing designs for the sequence.

Tuesday, Jan. 26 (DOY 026)

A unique series of RSS occultation observations began today. As seen from Earth, Cassini passed first behind the plumes of Enceladus, then slipped behind the rings, the atmosphere of Saturn, and finally the planet itself.

While Cassini was behind Saturn, VIMS observed the tenuous D ring at high phase angles. When VIMS concluded its observation, Cassini turned its antenna back towards Earth to continue the atmospheric and rings occultation experiment. By taking advantage of opportunities such as this, RSS can study Saturn, its rings, and moons at relatively long wavelengths, and provide data that complements that obtained by the other instruments.

The Cassini-Huygens Analysis and Results of the Mission (CHARM) teleconference for January was held today. The topic: Cassini's Auroral Observing Program. Once posted, PDFs of the presentations can be found online at:

An encounter strategy meeting was held today to cover the period from Jan. 28 to Mar. 2, satellite encounters Titan 66 and Rhea 2, and maneuvers 236-238.

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