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Cassini Update - September 4, 2009

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Old September 5th 09, 01:26 AM posted to sci.space.news
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Default Cassini Update - September 4, 2009

Cassini Significant Events
for 08/26/09 - 09/01/09

The most recent spacecraft telemetry was acquired
on Sept. 1 from the Deep Space Network tracking
complex at Goldstone, California. 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:

Wednesday, Aug. 26 (DOY 238):

A two-day Titan Science Workshop held at the
California Institute of Technology began today.
Topics on the agenda included presentations and
discussions of Titan's gravity, hypsometry, spin
rate, temporal changes, surface composition,
surface temperature, sea-shoreline elevations,
lake distribution, composition and shape, and
future plans for observations in the proposed
Cassini Extended Extended mission.

This week Cassini science observations included
Visual and Infrared Mapping Spectrometer (VIMS)
high phase and low phase mosaics of the rings and
an occultation of alpOri by the F - D rings. The
Ultraviolet Imaging Spectrograph (UVIS) performed
an additional low incidence angle occultation.
Imaging Science (ISS) imaged Janus in the ring
shadow, observed a Telesto close flyby at ~24,700
km and 86 deg phase at closest approach,
performed a Titan cloud monitoring activity,
looked for shadows of vertical features in the
rings, performed a 9.5h radial scan of the main
rings, and created a lit face, high phase movie
in search of ring spokes. The Composite Infrared
Spectrometer (CIRS) also created a low-phase
thermal map of the rings and performed a 6h
equinox baseline observation. Finally both the
Cassini Plasma Spectrometer (CAPS) and
Magnetospheric and Plasma Science (MAPS) suite of
instruments each performed a 2-hour survey.

Thursday, Aug. 27 (DOY 239):

Non-targeted flybys of Pallene and Telesto occurred today.

In the Significant Events Report for Tuesday,
Aug. 18, it was reported that an anomaly occurred
in the Spacecraft Office (SCO) Integrated Test
Lab (ITL) between a CDS hardware interface and
the support equipment. Today SCO reported that
the ITL is back up and functioning in dual string
mode with the CDS flight spare and engineering
model computers. The problem was isolated to a
support equipment interface board. The
functionally equivalent board was removed from
CDS Test Bed 1 and moved to ITL Test Bed 3. SCO
is now working on having the problem board refurbished.

Friday, Aug. 28 (DOY 240):

At 6:30 PM, Pacific Daylight Time, JPL employees
were notified that due to brush fires in the
area, the primary Oak Grove site would be closed
to all but essential personnel over the weekend
as a precautionary measure. In this case for
Cassini, essential personnel included individuals
needed for the successful execution of Orbit Trim
Maneuver (OTM)-215 on Saturday morning.

Saturday, Aug. 29 (DOY 241):

Due to ongoing issues with the LCROSS spacecraft,
it was requested that Cassini give up the
beginning of two DSN tracks on DOY 241 and 243.
For DOY 241, DSN schedulers were able to obtain a
short DSS-55 track to maintain the full OTM-215
uplink window. On DOY-243, the decision was made
- with the concurrence of project management - to
accept the science data loss. This will result in
approximately 45 MB of data that will not be seen
on the ground due to the loss of DSS-65 track time.

Orbit Trim Maneuver (OTM) #215 was performed
today. This is the cleanup maneuver from the
Titan 61 encounter on Aug. 24. The main engine
burn began at 7:45 AM PDT. Telemetry immediately
after the maneuver showed the burn duration was
2.97 seconds, giving a delta-V of 0.50 m/s. All
subsystems reported nominal performance after the maneuver.

Monday, Aug. 31 (DOY 243):

JPL Update: Sunday, August 30, 2009, 4:45 pm
Fire conditions around JPL have continued to
improve throughout the day, and the Station Fire
no longer threatens the facility. However, there
has been heavy smoke in the area. To ensure
acceptable air quality for the safety of
employees, the Laboratory was closed on Monday
except for mission-critical personnel. A decision
regarding reporting to work on Tuesday will be made by Monday

Tuesday, Sept. 1 (DOY 244):

JPL resumed normal operations at 0600 hours Tuesday, September 1.

Science Planning handed over S55 sequence
development to Uplink Operations today at the
Science and Sequence Update Process (SSUP)
kickoff meeting. SSUP takes approximately 10
weeks and is the final sequence development
process just prior to uplink and execution of the
background sequence and all related products. The
first two weeks of DSN allocation beginning on
Nov. 13 have been negotiated. S55 DSN allocations
should be finalized by Sept. 9.

An image titled "Shadows of Saturn at Equinox" is
Astronomy Picture of the Day today. To view the image and caption link

An AACS Periodic Engineering Maintenance (PEM)
occurred today. Performed every 90 days, this
activity exercises the main engine gimbal
actuators, the backup Reaction Wheel Assembly
wheel, and scrubs some portions of memory. In the
RWA exercise, the wheel is commanded to +100 rpm,
-100 rpm, 0 rpm, then turned off.

The Science Forum for S57 was held today. Topics
included an overview of science planned for this
sequence followed by highlights/unique/highest
priority observations provided by the Target
Working Teams and Orbiter Science Team leads,
with comments from the Investigation Scientists
and other instrument team representatives.

Visit the JPL Cassini home page for more
information about the Cassini Project:

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