Cassini Update - July 20, 2007

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Cassini Significant Events 
for 07/11/07 - 07/17/07

The most recent spacecraft telemetry was acquired on Tuesday, July 17, from
the Goldstone 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, July 11 (DOY 192):

Leading up to the July 19 [July 18 PDT] Titan 34 flyby, the entire suite of
Magnetospheric and Plasma Science (MAPS) instruments conducted observations
of the magnetospheric boundaries.  In particular, the Magnetospheric Imaging
Instrument (MIMI) measured the energetic particle pitch angle distributions
near the boundaries, and characterized the upstream ion events.

The RADAR instrument obtained distant Titan radiometer science and
calibration data.  This is one of a set of near zero Titan sub-spacecraft
latitudes, fixed phase angle, and varying sub-spacecraft longitudes.  The
RADAR team likes to survey Titan at varying longitudes to reveal broad
surface emission variations.

On DOY 198, the Imagining Science Subsystem (ISS) performed a Rhea limb
topography and geodesy observation. 

Thursday, July 12 (DOY 193):

All Cassini teams and offices supported the Cassini Monthly Management
Review. 

An encounter strategy meeting was held today to cover the period between
July 19 and August 31, Titan flybys T34 and T35, and maneuvers 122-124.

Friday, July 13 (DOY 194):

As part of normal monitoring and maintenance, the spacecraft Command and
Data Subsystem team performed a Solid State Recorder (SSR) memory readout of
single and double bit error counters for all 128 sub-modules in each SSR.

The S31 sequence concluded and S32 began execution today at
2007-195T01:06:00.  Since that is SCET, or spacecraft event time, the
sequence actually began clocking out late on Friday in local time.The
sequence will run for 29 days and conclude on August 11, 2007.During that
time there will be one targeted encounter with Titan and two non-targeted
flybys - one each of Helene and Tethys.  Three maneuvers are scheduled,
numbered 121 through 123.

Sunday, July 15 (DOY 196):

Orbit Trim Maneuver (OTM) #121 was performed today.  This is the approach
maneuver setting up for the Titan 34 encounter on July 19.The reaction
control subsystem burn began at 4:29pm PST. Telemetry immediately after the
maneuver showed the burn duration was 7.0 seconds, giving a delta-V of 0.013
m/s. All subsystems reported nominal performance after the maneuver.
Hydrazine usage was about 20.9 g.  For this OTM, NAV biased the Titan
closest approach time by 0.39 seconds.  This made the maneuver large enough
to perform, and avoided a downstream cancellation delta-V cost of about 1
m/sec.OTM-118, completed on June 26, 2006, is still the shortest and
smallest OTM, at 6.875 seconds and 0.009 m/sec.

Monday, July 16 (DOY 197):

Today the sequence leads for S32 uplinked files for a RADAR mini-sequence
and for the DOY 199-200 Radio Science Live Update Block.

Tuesday, July 17 (DOY 198):

The final sequence development process for S34 kicked off today. The
sequence is unusual in that it will be composed of four parts.  The first
part is similar to a normal background sequence but will run for only two
weeks.  This is followed by uplink and checkout activities for CDS version
10 flight software that will last for about a week and a half.  During this
time period there will be no science observations.  After the conclusion of
the CDS activities, a mini-sequence devoted to Hyperion observations will
run for about four days.  The last piece of S34 is again like a normal
background sequence with full science activities. This will run for a little
over a week, concluding on or about November 1.  The Hyperion mini-sequence
base products and stripped subsequences and the sequence products for the
pieces of the S34 background sequence have been released for team review.

It has recently been reported that Saturn's distinctive moon Iapetus is
cryogenically frozen in the equivalent of its teenage years.Unlike any other
moon in the solar system, Iapetus is the same shape today as it was when it
was just a few hundred million years old, a well-preserved relic from the
time when the solar system was young. 
These results appear in the on-line version of the journal Icarus. 
For more information link to:

http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=761

The main engine cover was closed today as part of normal dust hazard
procedures.  The cover will remain closed for about four days and will
re-open on July 20 prior to OTM-122. This will be the 34th open/close cycle
since launch.  The next closure is scheduled for August 29, 2007.

The Cassini Imaging Team reports the discovery of S/2007 S 4, a satellite
orbiting in the region between Methone and Pallene. The satellite was first
discovered in a series of fifteen pairs of Cassini wide-angle camera images
with exposure times of 10 and 15 seconds, taken through the clear filter on
May 30, 2007, spanning 6 hr. Following a preliminary orbit fit, an
exhaustive search of other Cassini images generated a number of additional
detections. A more detailed description of this activity will appear soon on
the Cassini web site.
 

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.
    
   




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