Cassini Significant Events 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.
