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Cassini Significant Events for 12/09/04 - 12/15/04



Cassini Significant Events
for 12/09/04 - 12/15/04

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/operations/present-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-Huygens/SEMYOSXDE2E_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.

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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