|
Cassini Significant Events 11/10/10 - 11/16/10 The most recent spacecraft telemetry was acquired on Nov. 15
from the Deep Space Network tracking complex at Canberra, Australia. 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/mission/presentposition/.
Wednesday, Nov. 10 (DOY 314) Safing recovery efforts continued today with the uplink of
D9 modules and opmode transitions to perform sequence activities that were
halted with the safing event, but which were necessary for Orbit Trim Maneuver
#266 (OTM-266), OTM-267, and a Radio Science Subsystem (RSS) Ka-band
Operational Readiness Test (ORT). Files to power on the Cosmic Dust Analyzer
(CDA), the Cassini Plasma Spectrometer (CAPS), and the Magnetometer (MAG) were
also uplinked. The CAPS file is scheduled to execute just prior to the DSN pass
on Saturday, Nov. 13. A feature story called "Cassini Sees Saturn on a Cosmic
Dimmer Switch" is available on the Cassini web site. It describes how like
a cosmic light bulb on a dimmer switch, Saturn has emitted gradually less
energy each year from 2005 to 2009, according to observations by the Cassini
spacecraft. But unlike an ordinary bulb, Saturn's southern hemisphere
consistently emitted more energy than its northern hemisphere. On top of that,
energy levels changed with the seasons and differed from the last time a
spacecraft visited Saturn in the early 1980s. For more information on this
subject, link to: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20101110/ Thursday, Nov. 11 (DOY 315) The Titan-73 (T73) flyby at 7921 kilometers altitude
occurred today. No science data was taken since the spacecraft is still at the
Earth-pointed safing attitude with no background sequence executing. An article called "Saturn Then and Now: 30 Years Since
Voyager Visit" was posted on the Cassini web site today. Ed Stone, project
scientist for NASA's Voyager mission, remembers the first time he saw the kinks
in one of Saturn's narrowest rings. It was the day the Voyager 1 spacecraft
made its closest approach to the giant ringed planet 30 years ago. Scientists
were gathering in front of television monitors and in one another's offices
every day during this heady period to pore over the bewildering images and
other data streaming down to NASA's Jet Propulsion Laboratory in Pasadena,
Calif. For more information on this subject and images, link to: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20101111/ Friday, Nov. 12 (DOY 316) Today, real time command procedure SCO-1786 was performed to
load the A8.8.0 flight software into the backup AACS Flight Computer A (AFC-A)
from the Solid State Recorder (SSR) for a second time, as a result of last
week's safing incident. As a precaution, SSR auto repair was disabled during
the load from the SSR. The loading of A8.8.0 flight software to the AFCs is now
complete. DSS-14 had an emergency brake, a mechanical stop initially meant for
DSS-13 but which inadvertently affected DSS-14, resulting in the loss of
several Attitude and Articulation Control Subsystem (AACS) Memory Read Outs
(MROs). The SSR Instrument Expanded Block (IEB) loads for the
Imaging Science Subsystem (ISS), the Visual and Infrared Mapping Spectrometer
(VIMS), the Composite Infrared Spectrometer (CIRS), the Ultraviolet Imaging
Spectrograph (UVIS), and CAPS were uplinked successfully along with the CAPS
instrument direct IEB load today. Saturday, Nov. 13 (DOY 317) Additional instrument IEB loads for the S65 background
sequence were uplinked today. In addition, a file to power on the remaining
instruments - ISS, UVIS, CIRS, the Ion and Neutral Mass Spectrometer (INMS),
the Radio and Plasma Wave Science Subsystem (RPWS), and the Magnetospheric
Imaging Instrument Subsystem (MIMI) - was uplinked. All instruments are
scheduled to be up by end of day Monday, Nov. 15. The AACS MROs for procedure
SCO-1786 which were lost on DOY 316 were played back today. Sunday, Nov. 14 (DOY 318) A test of the backup reaction wheel assembly #3 (RWA-3) was
uplinked today. This test will execute Nov. 16-19. RWAs 3 and 4 will be spun in
opposite directions at two different rates to assess the health of RWA-3.
Increasing concerns with wheel 1 are prompting the consideration of bringing
wheel 3 back on line to support attitude control. Since wheel 4 is currently
configured to have its spin axis parallel with wheel 3's spin axis, running
them at equal speeds in opposite directions cancels out the momentum effects,
hence avoiding the use of hydrazine and perturbations to the trajectory. Monday, Nov. 15 (DOY 319) OTM-266, the T73 clean-up maneuver scheduled for today, was
cancelled. There was no impact to overall delta-V as the cost of cancellation
was only about 3 mm/sec. Cancellation also freed up the tracking pass for
safing recovery activities. Instrument Operations (IO) sent commands to power on the ISS
instrument and load flight software today. Tuesday, Nov. 16 (DOY 320) U.S. Cassini Scientist for a Day essays are being judged
this week. Award ceremonies for winners in Australia, New Zealand, and Peru
were held this week. A Cassini workshop proposal on Reading, Writing & Rings
was accepted for the National Science Teachers Association annual conference
that will be held in San Francisco in March 2011. ------------------------ To unsubscribe from Cassini Spacecraft Updates or to
subscribe with a different email address, visit here: <http://saturn.jpl.nasa.gov/news/mailinglistsignup/
> ------------------------ This email address is not monitored. For comments and
questions, please contact Cassini Outreach here: <http://saturn.jpl.nasa.gov/feedback/> ------------------------ Visit the JPL Cassini home page for more information about
the Cassini Project: <http://saturn.jpl.nasa.gov/> ------------------------ |
