Cassini Significant Events 02/09/06 - 02/15/06

February 17, 2006

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired Wednesday, February 15,
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 .

Thursday, February 9 (DOY 040):

The Mission Support and Services Office led a discussion on the issues and
processes related to regenerated spacecraft clock/spacecraft event time
(SCLK/SCET) files at the Cassini Design Team meeting. Topics included the
history and current implementation of the SCEGEN software and identified the
current limitations of the system. Further discussion with personnel from
the Spacecraft Operations Office, Navigation, and Radar teams to identify an
updated SCLK/SCET strategy is planned.

Two schools on opposite sides of Canada held complementary Saturn viewing
and Night Sky Watching events on February 9. Students and families at
Airdrie McCall School in Alberta and their partner school in Almonte,
Ontario, participated. There were 20 viewers in the West and 30 viewers in
the East. These events serve to start conversations between the students
about what can be seen at either end of the country. A Saturn Observation
Campaign (SOC) member in Airdrie, Alberta, Canada, coordinated the event.

A member of Cassini Outreach was in Perris CA this afternoon and evening for
a Saturn telescope night at Columbia Elementary School - named after the
space shuttle and the astronauts who lost their lives. Four telescopes were
provided for the event and the kids and one teacher operated them. One
hundred fifty children and their parents attended and observed the moon,
Saturn and the Beehive cluster.

Friday, February 10 (DOY 041):

As in each of the previous weeks of this sequence, part of the time was
devoted to instrument calibration. This week the Magnetometer Subsystem
(MAG) calibrated its boom alignment to check for changes with respect to the
spacecraft axes. Accurate knowledge of sensor orientation is necessary for
magnetic field measurement accuracy.

This was a productive week for imaging of satellites with 76 observations of
16 bodies. Orbit determination images were taken of Atlas, Pallene, Calypso,
Epimetheus, Janus, Helene, Prometheus, Pandora, Telesto, Pan, Methone, and
Polydeuces. A transit of Mimas across Tethys was captured, and Dione and
Enceladus were the subjects of optical navigation images.

Two of the observations this week were quite lengthy. The Imaging Science
Subsystem (ISS) and the Visible and Infrared Mapping Spectrometer (VIMS)
spent twenty-eight hours searching for a direct observation of lightning in
Saturn's atmosphere. Investigating the sources and nature of lightning on
Saturn can tell scientists more about the atmosphere and wind velocities on
the planet.

The S20 Science Operations Plan (SOP) Update process completed today. The
product was handed off to the sequence leads for the kickoff of the final
development process.

Files were radiated to the spacecraft today to modify an instrument expanded
block file for the Cosmic Dust Analyzer (CDA), and to patch the flight
software for the Composite Infrared Spectrometer (CIRS). Both files have
been registered and are active on-board the spacecraft. The CDA file will
begin execution on Monday, February 13, and the CIRS file will execute on
Wednesday, February 15.

The Titan 11,12, 13, and 14 preview meeting hosted by the Titan Orbiter
Science Team (TOST) was held today. The main emphasis of the meeting
focused on first time events by the Radio Science Subsystem as well as goals
regarding the atmosphere of Titan.

A Cassini Pyro Valve 40/41 review was held today. This was in preparation
for the Monopropellant Tank Assembly (MTA) recharge activity planned for
April 10, 2006.

Saturday, February 11 (DOY 042):

The annual ACS Inertial Reference Unit (IRU) calibration was performed on
February 11 and 12. This was an ACS-centric calibration, where the
spacecraft turned through large angles. Other calibrations are done
throughout the year, but are piggybacked onto smaller turns. The
calibration executed nominally. The per-axis biases and misalignment errors
are better than the requirements. The next piggyback calibration will be on
July 28, 2006.

Today the Astronomical Observatory in San Juan Talpa, El Salvador, opened
its doors for people to enjoy observations of Saturn. The activity began at
6:30 pm with a Saturn lecture, detailing the latest discoveries of Cassini.
Later people utilized the telescope of the observatory to observe Saturn and
some of its moons. Additional telescopes from some members of ASTRO were
installed on the north terrace of the observatory.

Sunday, February 12 (DOY 043):

On Sunday the Ulysses Project contacted Cassini to ask to use part of our
DSS-14 support to accomplish their commanding. The S-band transmitter at
their own station, DSS-24 had been declared red. After obtaining
concurrence from the sequence leads, Spacecraft Operations Office, and the
Navigation team, Cassini negotiated to use the DSS-24 X-band transmitter to
ensure coherent Doppler coverage for a scheduled reaction wheel assembly
bias activity, and gave up 60 minutes of DSS-14 during 165kbps telemetry
playback. As it turned out, the actual time was from 2006/044-05:29:56 (ERT)
to 2006/044-06:31:23 (ERT). The total outage for Cassini was ~30 minutes.

Spacecraft Periodic Engineering Maintenance (PEM) B was successfully
performed today. This activity "exercised" mechanical parts of the Engine
Gimbal Actuators, and scrubbed the memory in the Backdoor Assisted Load
Format Injection Loader.

The Saturn Observation Campaign (SOC) is alive and well in the Netherlands.
A charter member of the SOC submitted this report of their activities:
"Every Sunday at 5 o'olock we have our Saturn Mission Film, still based on
the Ring World, in our planetarium dome of the Europlanetarium in Genk,
Belgium. After that we go up into the cupola to look with our telescope for
Saturn where I will tell 26th of Feb. about the Cassini-Huygens mission."

Monday, February 13 (DOY 044):

The CDS Command Loss Timer (CLT) Memory Corruption flight software patch was
approved at a change control board meeting today in preparation for uplink
May 8-11. This patch corrects a code error found last September in the
execution of the "set Command Loss Timer" command. The error was discovered
when the CLT was set back for Orbit Trim Maneuver 31. This resulted in data
lost for the Titan 7 encounter. A patch to restore normal operations was
issued on September 15 to correct the then current situation. The delivery
of the patch today fixes the code.

Tuesday, February 14 (DOY 045):

Reference Trajectory update status and plans were discussed today in a
follow-up meeting to the Mission Planning Forum last week. Scientists and
the flight team are narrowing down the options and will make a decision on
which trajectory to select next week.

The radio and plasma wave science (RPWS) instrument on board Cassini has
captured radio emissions believed to come from a large lightning storm that
occurred on January 23 and 24 at Saturn. The sounds are similar to the
crackles and pops one hears on an AM radio during a thunderstorm on Earth.
Those radio emissions were converted into an audio file, and are now
available as a Podcast. To access the files go to: or or .

Wednesday, February 15 (DOY 046):

A file was uplinked to the spacecraft for Radio Science today to power cycle
the Ka-band Translator On/Off and S-Band ON/OFF for testing purposes. The
file has been registered and will begin execution on DOY 050T22:46:59.

A VIMS movie showing a rotating Titan in infrared light is Astronomy Picture
of the Day today.

Wrap up:

Check out the Cassini web site at 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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