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Cassini Significant Events 01/11/07-01/17/07

Cassini Significant Events 01/11/07-01/17/07

January 19, 2007

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired on Wednesday, Jan. 17, from the Goldstone 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 http://saturn.jpl.nasa.gov/operations/present-position.cfm

Thursday, Jan. 11 (DOY 011):

The Science Operations Plan Update (SOPU) process for S30 kicked off yesterday. The process will run for about 5 weeks, concluding at the end of February. The preliminary product input port is scheduled for Jan. 29.

The latest Cassini video report is available at: http://www.jpl.nasa.gov/videos/cassini/cassini20070111/

Friday, Jan. 12 (DOY 012):

The SOPU process for S29 concluded today. Products were handed off to the sequence leads for the kick-off of the final sequence development process next Wednesday.

Cassini is currently on approach for a flyby of Titan. During this period, the RADAR instrument obtained both distant radiometer science data and distant scatterometry science data, the Composite Infrared Spectrometer (CIRS) mapped Titan in both mid-infrared and far-infrared, integrated on Titan's limb to obtain information on trace constituents in Titan's stratosphere, and obtained measurement of organics, the Imaging Science Subsystem (ISS) provided ride-along context images and performed night side imaging, and the Visible and Infrared Mapping Spectrometer (VIMS) simultaneously made high resolution regional maps.

The Magnetosphere And Plasma Science instruments (MAPS) began a Titan Orbiter Science Campaign. Ion and Neutral Mass Spectrometer (INMS) measurements will be used to determine atmospheric and ionospheric thermal structure.

Saturday, Jan. 13 (DOY 013):

Today Cassini passed by Titan at an altitude of 1000 km and a speed of 6.0 km/sec for the 24th targeted encounter of that satellite. This is the first of 17 Titan flybys planned for 2007. In addition there will also be a targeted encounter with Iapetus, bringing the total up to 18 targeted flybys, more than in any other year during the 4-year prime mission for Cassini.

Science for this flyby included RADAR high latitude radiometry maps of both the north and south poles to understand seasonal temperature, and obtaining synthetic aperture radar (SAR) images over the anti-Saturn hemisphere from mid-north to low south latitudes, which will be useful for studying dune orientation.

At the same time, INMS measured Titan's atmospheric and ionospheric composition and thermal structure. This was the first INMS data from the dayside, inner flank. The other MAPS instruments observed Titan's interaction with Saturn's magnetosphere with the Radio and Plasma Wave Science (RPWS) in particular concentrating on evidence of ion pickup, radio emissions, density profiles, and the general wave environment.

Outbound from Titan, UVIS observed as Titan occulted Eta UMa. From this data, the vertical distribution of hydrocarbons and an atmospheric temperature profile can be deduced. After additional RADAR SAR imaging, the Optical Remote Sensing (ORS) instruments with ISS prime spent several hours on a global map of Titan.

Sunday, Jan. 14 (DOY 014):

Today marks the second anniversary of the Huygens Probe entry, descent, and data relay from Titan on Jan. 14, 2005. The European Space Agency is carrying an article on their website reviewing the event, and discussing some of the ongoing results from data analysis.

Images supporting this release are available at

Monday, Jan. 15 (DOY 015):

Orbit Trim Maneuver (OTM) #89 was performed today. This is the cleanup maneuver from the Titan 23 encounter on Jan. 13. The reaction control subsystem burn began at 7:45 PM PST. Telemetry immediately after the maneuver showed the burn duration was 158.5 seconds, giving a delta-V of 0.21 m/s. All subsystems reported nominal performance after the maneuver.

Today the ORS instruments, VIMS, CIRS, ISS, and UVIS, made a mosaic of each ansa of the rings as part of ongoing efforts to view the rings at different latitudes and phase angles. UVIS and CIRS then studied the rings by observing an occultation of the bright star Delta Per, a hot, luminous, B5 giant. This occultation was a full radial cut through all the rings on the south face in the planet's shadow. A third ring observation for the day was a study by CIRS of the vertical motion of ring particles around the ring plane.

Tuesday, Jan. 16 (DOY 016):

The Extended Mission Guidelines and Constraints Working Group met today to continue review of the draft document.

The Titan Atmosphere Model Working Group (TAMWG) met today to discuss Titan atmosphere density results for flybys through Titan 21. The meeting was to review old flyby data to update the atmosphere model and not to present recent results from T22 or T23. Presentations included a 2D model of latitude/height for the Titan atmosphere from INMS data, with an interesting conclusion that night side passes show hotter temperatures by 20 to 30 degrees over the simple model, a summary of previous results from INMS, AACS, and HASI data, a worksheet with predicted density for all future flybys in the prime mission and compared to flyby tumble densities from AACS, a summary of AACS, INMS, and Navigation results, and finally a presentation of analyses that showed gravity gradient and boom deflections were effects that could be ignored.

The next TAMWG is scheduled for May 10. The purpose of this meeting will be to review the results of flybys from T22 through T29.

Wednesday, Jan. 17 (DOY 017):

The Spacecraft Operations Office (SCO) maneuver team began a series of internal training sessions today. Instructors are pulled from both the Navigation team and SCO to discuss such maneuver related topics as orbit determination, fault protection, Maneuver Automation Software version 6.1 capabilities, new maneuver block structures, and applicable spacecraft subsystems. These sessions will meet weekly until mid-April, 2007.

AACS flight software version A8.7.5 passed the final gate today when it was approved for uplink at a Software Review/Certification Requirements review.

The final sequence development process for S29 kicked off today. The Science and Sequence Update Process (SSUP) runs for approximately ten weeks and will conclude at the end of March. Already this week two meetings were held to discuss reaction wheel biasing strategy, and the stripped spacecraft activity sequence files were released to the instrument teams, SCO, and Navigation for review.

The sequence leads for S28 reported that Integrated Test Laboratory testing for the Titan 27 flyby is now concluded, and that negotiations for DSN coverage are complete through DOY 70. Coverage is still pending for the period from DOY 71-86. All is scheduled to be complete by Wednesday, Jan. 24.

After a two-part meeting - the first held on Dec.18 and the second held today - the project has elected to implement the following tweaks to the prime mission trajectory:

The Titan 32 flyby altitude will be raised by 25 km from 950km to 975km.
The Iapetus trajectory will be altered to improve science data acquisition for this the only close Iapetus flyby in both the prime and proposed extended missions.

The delta-v cost for these adjustments is 14 m/s, all of which is due to Iapetus + ripple effect minimization. Changes to the trajectory will only occur from just before Titan 32 to just after Titan 36.

Today the ORS instruments turned their attention to Rhea, 457,000 km distant from Cassini. VIMS, the prime instrument, did regional geodesy and global color. UVIS measured the ultraviolet albedo.