Status Report

NASA Cassini Significant Events for 07/11/07 – 07/17/07

By SpaceRef Editor
July 23, 2007
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NASA 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

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: 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 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.

SpaceRef staff editor.