Cassini Update - January 19, 2007

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

The most recent spacecraft telemetry was acquired Wednesday, January 17,
from the Goldstone tracking complexes. The Cassini spacecraft is in an
excellent state of health and is operating normally. Information on the
present position and speed of the Cassini spacecraft may be found on the
"Present Position" web page located at
http://saturn.jpl.nasa.gov/operations/present-position.cfm .

Thursday, January 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, January 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, January 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, January 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:

http://www.esa.int/esaCP/SEM7QJRMTWE_index_0.html

Images supporting this release are available at

http://www.esa.int/esaCP/SEM7QJRMTWE_index_1.html

Monday, January 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, January 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, January 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.

Wrap up:

Check out the Cassini web site at http://saturn.jpl.nasa.gov for the latest
press releases and images.

The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a
division of the California Institute of Technology in Pasadena, manages the
Cassini-Huygens mission for NASA's Science Mission Directorate, Washington,
D.C.  JPL designed, developed and assembled the Cassini orbiter.
 
 




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