Cassini Significant Events 09/21/06 - 09/27/06

September 29, 2006

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired Wednesday, Sept. 27,
from the Goldstone 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" page at .

Thursday, Sept. 21 (DOY 264):

Legislative Affairs presented 20 JPL packets to California Assemblywoman
Carol Liu's office as they will meet and greet a contingent including
several people from the Vatican in Sacramento next week. The packet included
the Ring World2 DVD, Cassini's "Jewel of the Solar System" poster, and Solar
system lithographs.

Cassini also provided materials to Legislative Affairs for Congressman
Calvert's office and their annual Science and Technology Education
Partnership conference. Three thousand folders were sent to support this

The discovery of the new ring, some amazing images including some from the
Titan 17 flyby, and an image of Earth from Saturn taken by Cassini kept the
web team busy posting releases and images:

- Titan's "Kissing Lakes"/ Sept. 26

- Long-lived Vortices/ Sept. 26

- Duotone Moon/ Sept. 25

- Blustery Bands/ Sept. 22

- Pale Blue Orb (2)/ Sept. 19

- Ghostly Fingers of Enceladus/ Sept. 19

- The Janus/Epimetheus Ring/ Sept. 19

Outreach presented an overview of Cassini-Huygens Education and Public
Outreach (EPO) to scientists and outreach specialists from throughout Europe
at "Europlanet" in Berlin, Germany last week. While the major focus of the
conference was scientific, an entire session day was devoted to outreach and
the vital role scientists play in boosting the public's awareness and
support for space science. Over 50 people attended the session, which
included talks from the European journalism community, university
researchers, and EPO specialists from the European Space Agency.

Friday, Sept. 22 (DOY 265):

The Titan Orbiter Science Team hosted a Titan 19, 20, 21, and 22-flyby
preview today. The goal of the meeting was to review the science objectives,
measurements, and science acquisition planned for each of the flybys.

Saturday, Sept. 23 (DOY 266):

On Saturday, Sept. 23, Cassini flew by Titan at an altitude of 960km and
a latitude of 71 degrees. Throughout the flyby, Magnetospheric and Plasma
Science (MAPS) teams performed observations of Titan's interaction with
Saturn's magnetosphere, and the Visual and Infrared Mapping Spectrometer
obtained visible and infrared images at high, medium and global resolution.
The closest approach time was significant as the Ion and Neutral Mass
Spectrometer (INMS) was able to obtain data to help determine Titan's
atmospheric and ionospheric composition and thermal structure. RADAR also
completed several minutes of Synthetic Aperture Radar coverage of Titan's
surface near closest approach. For a full description of the flyby link to:

Near periapsis, two days later, the Composite Infrared Spectrometer executed
a radial scan of the main rings to obtain sub-millimeter wavelength
measurements at a variety of geometries, and the Magnetospheric Imaging
Instrument imaged certain dynamics of the inner magnetosphere. Additional
ring observations were carried out by all of the Optical Remote Sensing
instruments by observing a star as the rings occulted its light.

Sunday, Sept. 24 (DOY 267):

The DOY 268 Live Inertial Vector Propagator Update of the Janus vector was
uplinked to the spacecraft today at 267/16:51:40. Confirmation has been
received that it is on board and registered.

Monday, Sept. 25 (DOY 268):

A non-targeted flyby of Methone occurred today at an altitude of 63,731 km.
After canceling Orbit Trim Maneuver (OTM) #73 last week, the Navigation team
took a look at the impact of canceling OTM-074 as well. OTM-074 currently
has a magnitude of 0.33 m/s, and is the T18 cleanup maneuver set for
Sept. 26. Since OTM-75 is a fairly large deterministic maneuver, the
overall cost of canceling OTM-74 is about 0.2 m/s. It has been decided to
cancel OTM-74 and roll the delta V into OTM-075.

Navigation has delivered the "no maneuver" trajectory to Science Planning,
the project file repository, and the DSN. These files do not include OTM-75
and thus are only valid up to the time of OTM-75 execution on Oct. 1. A
Reaction Wheel Bias command has been approved and will be uplinked on
tomorrow morning's pass. Science Planning will now do a formal analysis to
determine if a live update to adjust instrument pointing is required as a
result of the OTM-74 cancellation.

The S27 preliminary port delivery occurred today in support of the Science
Operations Plan Update process. The analysis of the merge has been delivered
to the teams for review. The official port is scheduled for Friday,
Sept. 29.

Tuesday, Sept. 26 (DOY 269):

A Cassini-Huygens Analysis and Results of the Mission (CHARM) telecon was
held today. The topic was "Titan: The Solar System's Abiotic Petroleum
Factory" and was presented by the team leader for the Cassini Ion and
Neutral Mass Spectrometer investigation. A PDF of this and previous
presentations may be downloaded by linking to:

CHARM telecons are the last Tuesday of the month from 11:00 am to 1:00 pm
Pacific Time.

On Tuesday, Sept. 26, media relations and the RADAR team issued two
RADAR images from the Titan 18 flyby showing more lakes. Although this pass
was primarily dedicated to the ion and neutral mass spectrometer instrument
and the volume of radar data was small, scientists were amazed to see
Earth-like lakes appear in radar images. The images can be viewed at:


Wednesday, Sept. 27 (DOY 270):

The Titan Atmosphere Model Working Group (TAMWG) met today to discuss post
T18 results. INMS, AACS, and Navigation calculated densities at the T18
flyby that were slightly below pre-flyby model estimates. In this case, the
duty cycle was predicted at 49% and the actual was 42%. Duty cycling is a
measurement of how often the thrusters fire in order to keep the spacecraft
pointed in the correct direction in response to atmosphere-generated
torques. 100% duty cycles would mean that the thrusters are firing all the
time. The percentages reported after the T18 flyby indicate that the data is
consistent with other nearby data points and does not indicate that there is
significant risk of losing attitude for the upcoming T19 or T20 flybys. The
TAMWG agreed to refine the atmosphere model and update duty cycle and
density predictions for all future flybys by January 2007.

A Delivery Coordination Meeting was held today for the Imaging Science
Subsystem Pre-Commanding Tool (ISSPT) version 2.6.5. ISSPT was developed by
the Cassini ISS Team to adjust and optimize ISS camera settings, calculate
image brightness levels and compression based on pointing, and produce
Instrument Operations Interface (IOI) output files used in building camera
command sequences.

An image of the rings of Saturn with Earth in the far distance is Astronomy
Picture of the Day today.