Cassini Update - September 26, 2008
- From: baalke@xxxxxxxxxxxxx
- Date: Mon, 29 Sep 2008 11:02:56 -0700 (PDT)
Cassini Significant Events
for 09/17/08 - 09/23/08
The most recent spacecraft telemetry was acquired on Sept. 23 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, Sept. 17 (DOY 261):
The Fall 2008 edition of the Cassini Scientist for a Day essay
contest was launched on Sept. 16. The contest is open to all grade
5-12 students in the United States. Participating students will be
competing in one of three groups, grades 5-6, grades 7-8, and grades
9-12. Targets for this contest are Tethys, Titan, and
Mimas. Students will write a 500-word essay defending their
selection of one of these three targets. The essay contest has a
deadline of Oct. 30, 2008, and Cassini will obtain the images on Nov.
26, 2008. Winners will be invited to participate in a teleconference
with Cassini scientists. For more information, videos, and complete
contest rules, teachers and students can visit the contest website
at: http://saturn.jpl.nasa.gov/education/scientist/6th_edition/
A flyer summarizing the contest can be found at:
http://saturn.jpl.nasa.gov/education/scientist/6th_edition/resources.cfm
Any questions regarding the contest should be e-mailed to:
scientistforaday@xxxxxxxxxxxx
Non-targeted flybys of Pandora, Mimas, Calypso, and Daphnis occurred
today.
The final integrated S49 sequence segments for orbits 106 - 110 are
due from the Target Working Teams and Orbiter Science Teams
today. These integrated products will be in sequence level form and
ready for the start of Science Operations Plan implementation.
Science teams will begin work on their pointing designs on Sept.
19. The final Cassini DSN station requests will also be delivered to
the DSN schedulers on the 19th. The official kick-off meeting for
S49 is scheduled for Oct. 1.
Wednesday was a busy day on the spacecraft as Ultraviolet Imaging
Spectrograph (UVIS) and Visual and Infrared Mapping Spectrometer
(VIMS) observed stars passing behind the rings, the Composite
Infrared Spectrometer (CIRS) observed Enceladus in eclipse behind
Saturn to look for sources of endogenic energy in the south polar
region, the Magnetospheric and Plasma Science (MAPS) instruments
collected at increased rates to observe auroral magnetosphere and
Saturn Kilometric Radiation source regions, and the Imaging Science
Subsystem (ISS) Narrow Angle Camera (NAC) performed non-contiguous
azimuthal scans of the rings targeted on a particular ringlet, the A
ring group, and observed Enceladus at an intermediate phase angle to
monitor plume activity.
Thursday, Sept. 18 (DOY 262):
The Main Engine (ME) cover was opened today. It has been closed for
the last 25 days, having been closed (deployed) on Aug. 24. This
completes the 44th cycle of the cover. During that time there were
only a few potential dust hazards, but since the time frame included
Superior Conjunction - a time of possible limited communication with
the spacecraft - and the Project has a policy of limiting the number
of cover cycles, it made good sense to just keep it closed until the
next main engine burn. The next cover deployment is on Sept.
21. For that cycle the cover will remain closed for four days and
will reopen on Sept. 25.
Friday, Sept. 19 (DOY 263):
Reading, Writing and Rings (RWR) has been published in the September
2008 issue of the National Science Teachers Association (NSTA)
journal "Science and Children," and awarded a SciLinks from the
National Science Teachers Association. This means key textbook
subjects will be linked to RWR as an NSTA approved web
page. SciLinks has registered more than 156,000 teachers and nearly
640,000 students. In addition, representatives from the publication
Education Week shadowed our partners, the Bay Area Writing project,
as they began beta testing the outreach follow-on language arts
product "Through the Eyes of a Scientist." Education Week.org
circulation has about 725,000 registered users.
Science today began with nine hours of VIMS observing as a star
occulted the outer C Ring. After a 9-hour downlink, CIRS continued
its campaign to thermally map and monitor the rings. Finally today
completed with an ISS lit-side low phase ring movie to search for
spoke periodicities.
Saturday, Sept. 20 (DOY 264):
Commands were sent to the spacecraft today for Orbit Trim Maneuver
#164a, a real-time reaction wheel bias to execute over the 164a
backup pass, Live Update #2 to execute on DOY-268, and a CDA ring
plane crossing activity for DOY-269.
Orbit Trim Maneuver (OTM) #164a was performed today. This is the
cleanup maneuver from the Enceladus 4 encounter on Aug. 11. The main
engine burn began at 1:15 PM PDT. Telemetry immediately after the
maneuver showed the burn duration was 5.3 seconds, giving a delta-V
of 0.88 m/s. All subsystems reported nominal performance after the
maneuver.
On Sunday the spacecraft will again be primarily taking data with the
NAC. The camera will begin with orbit determination observations of
several small satellites, including Pan, Epimethius, Prometheus, and
Janus. Next an image will be taken as part of a Titan cloud
monitoring campaign. Then the camera turns to Rhea for a low phase
angle observation with UVIS riding along. Coming into the home
stretch, three optical navigation images are taken, and to end the
day, images of Mimas with UVIS again riding along are planned.
Monday, Sept. 22 (DOY 266):
Teams made the first delivery today as part of the Science Operations
Plan process for S48.
Tuesday, Sept. 23 (DOY 267):
An AACS Periodic Engineering Maintenance was completed on the
spacecraft today. In addition, a friction test of the backup
reaction wheel (RWA) was performed. For this test, performed every
six months, the RWA is spun up to 600 rpm in both the clockwise and
counterclockwise directions and timed as it is allowed to run down to
zero.
The third potential Live Update for S44 would cover DOY 275-277 and
modify vectors for Saturn and Tethys. Science Planning has already
performed some analysis and finds the errors are minimal, and is
recommending a *NO-GO* for the live update. CIRS, ISS, and UVIS have
observations of designated targets during this period and will be
responding over the next day or so with their inputs to the decision.
.
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