Cassini Update - December 17, 2004

http://saturn.jpl.nasa.gov/news/pres...41217-ws-a.cfm

Cassini Significant Event Report
For Week Ending 12/17/04

The most recent spacecraft
telemetry was acquired from the Goldstone tracking station on
Wednesday,
December 15. The Cassini spacecraft is in an excellent state of health
and is operating normally. As of yesterday (December 16), the Program
is 8 days from Probe release and 29 days from Probe relay. 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/operation...t-position.cfm .

The S06 background sequence completed on the spacecraft this week.
A number of key activities had to be performed on the ground in support

of the Titan-b (Tb) and Dione flybys. Within three days, the Dione live

update process kicked off, a Go/No Go meeting was held, and the
necessary
Dione and Mimas vector files were uplinked to the spacecraft along with

Radar trigger commands. All executed as expected on December 14. After
Dione, files were sent to the spacecraft to open the Main Engine cover
in preparation for Orbital Trim Maneuver 8 (OTM), the Probe Targeting
Maneuver (PTM). The PTM executes on December 16.

This week's main event was the Titan-B flyby with closest approach on
348T11:38 Spacecraft Event Time. At this time the orientation for CAPS
allowed it to observe Titan's
ionosphere and magnetospheric interaction on the inbound leg and until
25 minutes after closest approach. The Composite Infrared Spectrometer
(CIRS) performed a 2-hour limb integration using the mid-IR detectors
to search for new molecules in Titan's stratosphere. CIRS continued the

campaign of far-IR integrations begun at T0 to search for species at
longer
wavelengths, and obtain a thermal map of the stratosphere, lending
insight
into the dynamics of Titan's atmosphere.

After a two-day Titan movie
sequence where the Imaging Science Subsystem (ISS) looked for cloud
motions,
Tb provided opportunities for imaging at high-resolution with pixel
scales
as small as a few 10s of meters and phase angles as low as 16 degrees.
ISS observations included the locations of the specular points during
both Ta and Tb, and of the Huygens landing site that will provide
stereo
coverage once the data from T10 is obtained. Outbound ride-along
observations
with VIMS provided a view of Titan's north polar region illuminated by
Saturn-shine.

From the Magnetometer Subsystem (MAG) point of view, the
objective of Tb was to study the development of the near wake or
magnetotail
after Ta had provided observations of the roots of it. MAG science will

thus be an important part of the three flybys Ta, Tb, and T3, which all

occur at almost the same Saturnian local time. These flybys are also
important
because of the increased variability of the incident plasma flow in the

Saturnian magnetosphere close to Saturnian local noon.

The Visual and Infrared Mapping Spectrometer (VIMS) actively observed
the
surface of Titan at small solar phase angles, investigated the
formation
and evolution of clouds on Titan, and searched for lightning, hot
spots,
and characterization of airglow.

The Ultraviolet Imaging Spectrograph (UVIS) executed a series
of EUV/FUV scans across Titan to create spectral images, and performed
two important stellar occultation measurements to better understand
Titan's
upper atmosphere, which will be used to support spacecraft operations
later next year, as well as for science purposes.

Following the Titan-B
flyby, CIRS obtained its first dark side FP1 map of Dione on Rev B.
CIRS
looked for thermal anomalies and will use the data to investigate
Dione's
thermal inertia. This flyby was the third closest approach to Dione -
at approximately 80,000 kilometers - during the nominal tour. ISS
observations
were taken of the trailing hemisphere of this satellite where the
strange
"wispy streaks" are located.

The Spacecraft, Uplink, and Navigation
teams completed the last official Operational Readiness Test (ORT) on
December 9. This test ran from Probe Release through the playback of
the
Probe Imaging Optical Navigation images. The timing was very tight with

multiple interfaces and the ORT was useful in flushing out issues.

Conforming
Planet Physical and Cartographic Constraints files were released by
Instrument
Operations. One contains Sun, Earth, Moon, Jupiter, Saturn and Uranus
and major Saturnian satellites and is compatible with the new reference

trajectory. The other contains minor Saturnian satellites and outer
irregular
satellites and is compatible with the new Rocks Spacecraft and Planet
ephemeris data file.

In preparation for the start of execution on December
16, thirteen instrument files were uplinked to the spacecraft along
with
the S07 background sequence.

Preliminary Sequence Integration and Validation
2 Cycle 1 products were delivered as part of the Science and Sequence
Update Process for S08. S09 is still in the Sub-Sequence Generation
phase
of development. Teams are currently validating pointing designs with
respect
to the new reference trajectory.

The results of the ACS analysis of
the port #1 delivery for S10, S39, and S40 have been published. S10 is
currently in Science Operations Plan (SOP) Update and S39/S40 are in
SOP
Implementation.

The decision meeting for the Aftermarket process for
S12 was canceled this week since all of the requested changes fit
within
the allocated resources.

The VIMS team has begun investigation of the
feasibility of rerunning early cruise VIMS data with newer telemetry
processor.
This would improve the quality of the data going to archive next year.
Evaluation of known problems and a test run of data is underway.

All teams and offices supported this month's Cassini Monthly Management

Review.

Two delivery coordination meetings were held this week. The first was
a Mission Planning delivery of AP_DOWNLINK V6.0, and the second was for

an updated version of the Command Data Base 11a. This delivery will be
used with Mission Sequence Subsystem version D11 when it is delivered
in May of next year.

The Mission Support and Services Office reported
that they have had to rescind an offer of ACE support to the Deep
Impact
project. Now that the Deep Impact launch has moved to January 12, it is

very close to Probe Relay operations. Neither project wanted to
negatively
affect operations for the other, so the support was cancelled.

European Space Agency (ESA) scientists have teamed up with the Joint
Institute for Very Long Baseline Interferometry in Europe (JIVE) for
an experiment, which is expected to bring unique information from the
Huygens probe during its descent through Titan's atmosphere. They
intend
to use a technique called Very Long Baseline Interferometry (VLBI) to
pick-up the probe's faint radio signal here on Earth and use it for
reconstruction of the descent trajectory of the probe in the atmosphere

of Titan. For more information, go to the ESA web site at

http://www.esa.int/SPECIALS/Cassini-...OSXDE2E_0.html .

The most recent Cassini Mission Status Report can be found at

http://www.jpl.nasa.gov/news/news.cfm?release=2004-288 .

Image advisories, press releases and the latest Cassini information
can be found at http://saturn.jpl.nasa.gov .