Cassini Significant Events 12/10/08 - 12/16/08
The most recent spacecraft telemetry was acquired on Dec. 16 from the
Deep Space Network tracking complex at Madrid, Spain. The Cassini
spacecraft is in an excellent state of health and all subsystems are
operating normally. Information on the present position and speed of the
Cassini spacecraft may be found on the "Present Position" page
at:
http://saturn.jpl.nasa.gov/operations/present-position.cfm.
Wednesday, Dec. 10 (DOY 345):
An encounter strategy meeting was held today to cover the period
between Dec. 21 and Feb. 7, Titan flybys T49 and T50, and maneuvers
179-181.
Today Imaging Science (ISS) performed a 6.5 hour azimuthal scan of a 1.47
Rs ringlet. Following the scan ISS undertook a 13-hour medium
resolution observation of the F ring to produce a movie with the
Composite Infrared Spectrometer (CIRS) and Visual and Infrared Mapping
Spectrometer (VIMS) riding along.
Thursday, Dec. 11 (DOY 346):
On Thursday, December 11, the Titan Orbiter Science Team (TOST) hosted a
meeting to integrate the "caboose" TOST segments. These
are one to two day periods added to some Extended Mission TOST segments ?
Titan 63-66 and Titan 68-70 - after the "main" downlink in
order to accommodate Titan monitoring. The plan is to gather inputs
from the instrument teams for all caboose segments at a single
meeting. Following that, the TOST lead responsible for that segment
will act as a block lead for the associated caboose(s), and will generate
a proposed timeline for review.
Friday, Dec. 12 (DOY 347):
Two meetings were held today related to ongoing operations of the
spacecraft. The first was an Operational Readiness Review for the
propulsion system fuel-side repressurization activity scheduled for
January 2009. The second was an AACS flight software (FSW) version
A8.7.7 Change Control Board. The updated FSW will be placed onboard
the spacecraft in June of 2009 and modifies the default values for the
secondary safing vector pair, thruster force magnitudes, and spacecraft
mass properties.
Part 2 of the S46 background sequence was uplinked to the spacecraft
today. The file will execute on DOY-358, Dec. 23. The
Saturn/Rhea DOY 351-354 Live Inertial Vector Propagator Update file was
also sent. Both files are registered and activated
on-board.
Saturday, Dec. 13 (DOY 348):
Orbit Trim Maneuver (OTM) #177 was performed today. This is the
apoapsis maneuver setting up for the Titan 49 encounter on Dec. 21.
The main engine burn began at 1:30 PM PST. Telemetry immediately after
the maneuver showed the burn duration was 9.725 seconds, giving a delta-V
of 1.61 m/s. All subsystems reported nominal performance after the
maneuver.
Today the Cassini Plasma Spectrometer (CAPS) led the pointing for the
Magnetospheric and Plasma Science (MAPS) instruments? survey of the
magnetosphere. ISS observed the F ring for long-term temporal monitoring.
The Ultraviolet Imaging Spectrograph (UVIS) mapped volatiles in the
immediate neighborhood of Enceladus to test the connection of volatile
changes to plume eruptions. The Saturn segment began with CIRS performing
a compositional study of Saturn to measure oxygen compounds H2O and CO2
in the stratosphere as a function of latitude.
Monday, Dec. 15 (DOY 350):
At the American Geophysical Union meeting in San Francisco today,
there were press briefings held on new Cassini results from Titan and
Enceladus. The press releases may be seen at
http://saturn.jpl.nasa.gov/news/newsreleases/20081215titanvolcanoes/
and at
http://saturn.jpl.nasa.gov/news/newsreleases/20081215enceladusactivity/
Port three files were delivered today as part of the Science Operations
Plan process for S49. This is the final port for this
process. All files and products will be handed off to Uplink
Operations on Jan. 9, 2009, for final sequence development.
Most of today?s science observations were devoted to regional mapping of
the Saturn atmospheric composition by CIRS. The region studied is
typically about 15 degrees on a side and in this instance is centered on
45 degrees north latitude.
Tuesday, Dec. 16 (DOY 351):
Nine months ago, to support the Cassini Equinox Mission, the Outreach
team began working on a redesign of the Saturn homepage. That new look
and feel was released today at
http://saturn.jpl.nasa.gov/index.cfm.
Science today was divided between stellar occultations and polar dynamics
studies. The day began with VIMS observing a ring occultation of the star
Gamma Crucis - one of the stars in the Southern Cross. The other
occultations were of the stars Alp Cru and Beta Centauri by Saturn
observed in the ultraviolet by UVIS. These occultations provide
temperature of the high atmosphere and vertical profiles of H, H2 and
hydrocarbons.
From the dynamics studies, VIMS acquired 3-D imagery of the polar
regions in order to study the structure and dynamics of the polar
vortices and their variability over time, including seasonal changes. In
addition, images of the north pole - where sunlight is just beginning to
illuminate features - will reveal the structure and microphysical nature
of upper tropospheric clouds that help form the bizarre hexagonal feature
there.
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