NASA Cassini Significant Events 06/11/08 - 06/17/08

Status Report From: Jet Propulsion Laboratory
Posted: Tuesday, June 24, 2008


The most recent spacecraft telemetry was acquired on Tuesday, June 17, from the Goldstone, California, 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" page at:

Wednesday, June 11 (DOY 163)

Science activities today included the Ultraviolet Imaging Spectrograph (UVIS) performing calibration activities and a stellar ring occultation, and the Visual and Infrared Mapping Spectrometer (VIMS) obtaining images for a ring plane crossing movie.

Spacecraft Operations sent commands to the spacecraft to update the Reaction Control Subsystem (RCS) B branch thrust magnitude. This activity is performed periodically to keep the on-board thrust values in the flight software consistent with the actual physical values as the pressure decays in the hydrazine tank.

Thursday, June 12 (DOY 164)

The Navigation team has scheduled three critical Optical Navigation (OPNAV) events for August to support the Enceladus 4 flyby on Aug. 11. In this case, 'critical' means to provide extra support for the data processing and be prepared to intervene manually in case there is a problem with the data processing. Standard procedure is to wait until the end of pass to try a replay of the data if anything is missed. To support this request, members of the Multi-mission Image Processing Laboratory are reviewing and practicing procedures to ensure on-time delivery of image data to Navigation.

Friday, June 13 (DOY 165):

A non-targeted flyby of Titan occurred today.

Uplink Operations was busy this week sending commands to the spacecraft. Yesterday part 2 of the S41 background sequence was radiated. Sequence leads have verified that the file has been properly received and registered onboard. Execution will begin on Wed., June 18.

Commands were sent for Radio and Plasma Wave Science (RPWS) to modify direction finding in survey mode by changing from antenna 2 to antenna 3. Files for the DOY 168 S41 RSS Saturn Occultation Ingress Live Movable Block and the S41 Live Inertial Vector Propagator Update for Saturn, Mimas, and Dione were sent on DOY 167. The updated files will begin execution early Sunday morning.

On Sunday, VIMS will record movies on Saturn atmospheric dynamics and observe two stellar-ring occultations. The suite of Magnetospheric and Plasma Science (MAPS) instruments will observe the auroral crossing, and the Composite Infrared Spectrometer (CIRS) will perform radial scans of the rings and perform a nadir occultation observation. This observation will look to obtain spectra in the vicinity of previous Radio Science occultation points to obtain a new helium determination.

Monday, June 16 (DOY 168):

Non-targeted flybys of Epimetheus, Prometheus, and Methone occurred today.

Science Planning hosted the kick-off meeting for the S46 Science Operations Plan process today. The process will last about 14 weeks with final products being handed over to the Sequence leads for the final development process in September. S46 begins execution on-board the spacecraft on Nov. 26.

The Cassini Radio Science (RSS) orbit 72 Saturn atmospheric occultation observation was completed in the early hours of the morning today. The purpose of the activity was to observe the ingress to Saturn's ionosphere and atmosphere to measure vertical profiles of electron density in the ionosphere, and density, pressure, and temperature in the neutral atmosphere. Antennas at the Goldstone, Canberra and Narrabri complexes supported the experiment. Goldstone's DSS-14, 25 and 26 and Narrabri's DSS-47 provided partial support, while Canberra's DSS-43 and DSS-34 covered the entire experiment. This was the first time ever that four antennas tracked Ka-band simultaneously: DSS-25, 26, 34 and 47. Previously, three was the most to support this type of activity. RSS has one more science observation in the Cassini prime mission, the orbit 73 atmospheric occultation on DOY 175 (June 23) over Canberra and Narrabri.

The kick-off meeting for the fourth S41 Live Update, this time for DOY 173, occurred today. Based on the analysis and concurrence from Science Planning, Imaging Science, CIRS, and VIMS, the team will update the Saturn and Tethys vectors. The live movable block for RSS on DOY 175 will also updated.

Tuesday, June 17 (DOY 169):

Two members of the Spacecraft Operations Office (SCO) will be staffing the NASA exhibit at the Smithsonian Folk Life Festival in Washington, DC, the last week of June and first week of July.

SCO hosted an S47 Engineering Activities Review today to discuss all the spacecraft activities that will be performed during that sequence.

To wrap up the week, CIRS led a joint Optical Remote Sensing observation of a Rhea solar eclipse exit and performed radial ring scans, and VIMS collected data for Saturn movies.

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