Cassini Update - October 27, 2006

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Cassini Significant Events 
for 10/19/06 - 10/25/06

The most recent spacecraft telemetry was acquired Wednesday, October 25,
from the Madrid tracking stations. 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, October 19 (DOY 292):

An Encounter Strategy Meeting was held today for the maneuvers to occur
between Titan 20 and Titan 21. This will be for OTMs 80 through 82, and for
the period from October 25 through December 12.

Friday, October 20 (DOY 293):

Today was the last day of the 40th Cassini Project Science Group meeting.
Science investigators and other participants came to JPL for this week-long
discussion of science results and future planning. One of the most
significant items on the agenda was the selection of final tour candidates
for Extended Mission. 

The S25 background sequence was uplinked today at 293T11:39:35. The sequence
programs have been registered and activated. Execution will begin this
Sunday.

Orbit Trim Maneuver (OTM) #79 was performed on Sunday, October 22. This is
the approach maneuver setting up for the Titan 20 encounter on Wednesday.
The reaction control subsystem burn began at 9:45AM PDT. Telemetry obtained
after the maneuver showed the burn duration was 44.25 seconds, giving a
delta-V of 0.063 m/s. All subsystems reported nominal performance after the
maneuver.

Sunday, October 22 (DOY 295):

The keys to the spacecraft were handed over to the leads of the S25 sequence
today. S25 began execution at 2006-295T18:26:00 Spacecraft Event Time. The
sequence will run for 33 days, concluding on November 24. During that time
there will be one Titan targeted encounter, non-targeted encounters with
Telesto, Enceladus, Calypso, and Dione, and OTM-80 is planned to execute. On
the science side, the S25 sequence kicked off with an Ultraviolet Imaging
Spectrograph observation of Dione while the Magnetospheric and Plasma
Science instruments carried out a study of Saturn's magnetotail. The
magnetotail is the long anti-sunward extension of the magnetosphere. 

Wednesday, October 25 (DOY 298):

The first meeting of the Extended Mission (XM) Integration Guidelines and
Constraints Working Group was held today. The charter of this group is to
develop the XM integration Guidelines and Constraints document to be used by
the Target Working Teams and Orbiter Science Teams to integrate the
activities in extended mission. Meetings are scheduled to occur
semi-monthly.

STEREO launched successfully today from Cape Canaveral Air Force Base. Like
Cassini this was a night launch with a launch time of 8:52 EST. The
successful launch removed possible DSN conflicts on DOY 310 & 314 during the
48-hour launch contingency period. 

The Titan 20 flyby occurred today with closest approach at an altitude of
1030 km and eight degrees latitude. For this flyby, the main objective of
the Visual and Infrared Mapping Spectrometer (VIMS) was to acquire high
spatial resolution images of Titan's surface in order to characterize the
different units that have been discovered by either VIMS or RADAR. These
observations are considered to be some of the most critical for VIMS in the
prime mission. 

The low altitude of the T20 flyby made it possible to study the wake, tail
formation, and Saturn facing flank region, where the magnetic field topology
may be particularly complex. The Magnetometer team took advantage of this
very close approach which makes this orbit particularly useful for studies
of an internal magnetic field. 

Radio and Plasma Wave Science (RPWS) measured the thermal plasma properties
of Titan's ionosphere, including the electron density and pressure, as well
as characterizing the interaction of Saturn's magnetosphere with Titan. 

The Magnetospheric Imaging Instrument (MIMI) utilized T20's good orientation
to characterize the plasma flow, and to sample field-aligned energetic ions
and electrons. Titan, or at least part of Titan, will remain within the Ion
and Neutral Camera field of view throughout the close encounter, so MIMI
should be able to image the energetic ion/exosphere interaction though a
large range of geometries. 

Finally, RADAR will put together a radiometry map of northern Xanadu and
terrain up to 70 deg N latitude. 

The accelerometer (ACC) part of the Attitude and Articulation Control
Subsystem (AACS) was powered on for the T-20 encounter in order to have an
additional independent method to estimate the atmospheric density of Titan.
The team was able to capitalize on the spacecraft orientation during this
flyby. The aerodynamic forces and the reaction force due to the firing of
the z-facing thrusters would be pushing the spacecraft in the same
direction. Due to the combined effects of these two forces, it is expected
that the AAC data will show counts between 50 and 100. Further status on
this activity will be reported next week.

The JPL Stories program, sponsored by the Library, Archives, and Records
Section, celebrates the Lab's unique environment and history, and provides
an informal way for JPLers to share their stories with each other. This
week, the Cassini Virtual Singers presented "The History of Cassini-Huygens
in Song and Verse." This group of singers, non-singers, and those who want
to join in are all members of the Cassini Flight Team. The program was a
lighthearted look at the project from ATLO to launch, flybys to SOI -- as
memorialized in songs written by none other than the Cassini Virtual
Singers!

The Cassini project has released a dramatic portrait of the Saturnian
satellite Janus against the backdrop of Saturn. To view the image and the
full text description link to: 

http://saturn.jpl.nasa.gov/multimedia/images/image-details.cfm?imageID=2337

The Cassini Project has recently begun to produce video logs featuring
various members of the flight team who describe highlights of their areas of
involvement on the project as well as a brief description of what happened
with the last Titan flyby and what's in store for the upcoming one. The plan
is to produce one such product between each pair of Titan encounters. Three
are now available and can be viewed at:

http://www.jpl.nasa.gov/videos/cassini/cassini20061025/. 

Select from one of the four download options to view the video.

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 Spsce 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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