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VK1DSN > SPACE 30.12.07 23:16l 123 Lines 6049 Bytes #999 (0) @ VKNET
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Subj: Cassini Events 12/11/07
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Sent: 071216/1617Z @:VK1DSN.ACT.AUS.OC #:33703 [Canberra,QF44lo] FBB7.00i
From: VK1DSN@VK1DSN.ACT.AUS.OC
To : SPACE@VKNET
Cassini Significant Events
for 12/05/07 - 12/11/07
The most recent spacecraft telemetry was acquired on Tuesday, December 11, from
the Madrid tracking complex. 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" web page located at http://saturn.jpl.nasa.gov/operations/
present-position.cfm.
Wednesday, December 5 (DOY 339):
The S39 Science Operations Plan Update (SOPU) official port occurred today.
Inputs from participating instrument teams, Spacecraft Operations, and
Navigation were merged, and the reports delivered to the teams and AACS for the
end-to-end pointing analysis.
On Dec. 3, there was a large spike in Single Bit Errors (SBE) and Double Bit
Errors (DBE) on both SSRs. Usually the SBEs run about 25-50 per hour. This
spike lasted about 8 hours and got up to about 1850 per hour. DBEs typically
run about 2-3 per hour. This spike got up to 6 per hour. SBEs and DBEs are
believed to be caused by high energy particle hits. SBEs are autonomously
corrected by on-board error detection and correction (EDAC) logic. DBEs in
flight software are corrected by autonomous copies of the code from redundant
copies in the SSRs. DBEs in data regions of memory are not corrected, but go
away with the next writing of data into that area of memory.
Thursday, December 6 (DOY 340):
With Cassini now on the outbound leg of the T38 Titan encounter, a Radio
Science (RSS) gravity science experiment, mirroring the one performed as
Cassini approached Titan on DOY 338, was executed during the downlink to Earth.
For the remainder of the day, Imaging Science (ISS) produced images of Saturn'
s smaller moons for orbital element determination and observed the ring system,
focusing on the diffuse rings and making a mosaic of the ring system as a whole.
The S40 Aftermarket process was completed today. However, Science Planning is
still working on reducing Cassini's requested 70m DSN coverage during the
Phoenix Entry/Descent/Landing (EDL) contention period. Due to a hiatus in
sequence processing over the winter holidays, these changes aren't due until
Jan. 9, 2008.
Friday, December 7 (DOY 341):
As Cassini now swings outward beyond Saturn's magnetosphere, the Magnetospheric
and Plasma Science (MAPS) instruments resumed their monitoring of solar wind
conditions. The Visual and Infrared Mapping Spectrometer (VIMS) observed bright
stars to calibrate its sensors, and ISS resumed its monitoring of Saturn's
small satellites and produced a ring mosaic.
Orbit Trim Maneuver (OTM) #137 was performed today. This is the cleanup
maneuver following the T38 encounter on Dec. 5. The main engine burn began at
11:15 PM PST. Telemetry immediately after the maneuver showed a burn
duration of 4.18 seconds, giving a delta-V of 0.68 m/s, as planned. All
subsystems reported nominal performance after the maneuver.
Imaging scientists are putting together the story of how the small moons
orbiting near the outer rings of Saturn came to be. The moons began as leftover
shards from larger bodies that broke apart and filled out their "figures" with
the debris that made the rings. For the full story link to:
http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=795
Uplink Operations began sending the Instrument Expanded Block files for S36
today. Seven files for ISS, VIMS, Composite Infrared Spectrometer (CIRS),
Optical Navigation, Ultraviolet Imaging Spectrograph (UVIS), and Cassini Plasma
Spectrometer (CAPS) were sent. The remaining files will be sent Sunday and the
background sequence will go up on Monday. S36 will begin execution on Friday,
Dec. 14.
Sunday, December 9 (DOY 343)
Today the SSPS for the SRU-B replacement heater was tripped from OFF to TRIPPED.
The SSPS autonomous trip response fault protection algorithm
turned it back to OFF several minutes later. There appears to be no
correlation between this trip and the SBE and DBE activity seen earlier in the
week.
Monday, December 10 (DOY 344)
RSS performed a Saturn Occultation Operational Readiness Test (ORT) today.
There will be another ORT performed in the wee hours of the morning on Dec.
16, followed by the occultation itself later that day.
Tuesday, December 11 (DOY 345)
CIRS performed observations for determining the upper troposphere and
tropopause temperature of Saturn today.
The DOY-353 Live Movable Block (LMB) kickoff meeting was held today. The
meeting addressed the LMB and an additional Live Inertial Vector Propagator
update with RSS as the driving instrument. The Science Planning analysis and
recommendation is due late tonight with the Go/NoGo meeting to be held tomorrow.
Wrap up:
Check out the Cassini web site at http://saturn.jpl.nasa.gov for the latest
press releases and images.
The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a
division of the California Institute of Technology in Pasadena, manages the
Cassini-Huygens mission for NASA's Science Mission Directorate, Washington, D.C.
JPL designed, developed and assembled the Cassini orbiter.
---
Visit the JPL Cassini home page for more information about the Cassini Project:
<http://saturn.jpl.nasa.gov/>
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