Cassini Significant Events for 03/09/06 - 03/15/06

Cassini Significant Events
for 03/09/06 - 03/15/06

The most recent spacecraft telemetry was acquired Wednesday, March 15,
from the Goldstone tracking stations. The Cassini spacecraft is in an
excellent state of health and is operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the
“Present Position” web page located at .

Thursday, March 9 (DOY 068)

Members of the Spacecraft Operations Office (SCO) sent commands to the
spacecraft today for an ACS roll halt and end-of-sequence reaction
wheel assembly (RWA) bias for S19.

An Encounter Strategy Meeting was held for Titan flybys 12 and 13. The
period covered is March 18 through April 30, and includes maneuvers 56
through 58.

JPL put out an announcement on the Cassini discovery of potential
liquid water on Enceladus. High-resolution Cassini images show icy jets and towering plumes ejecting large quantities of particles at high speed.
Scientists examined several models to explain the process. The jets
might be erupting from near-surface pockets of liquid water above 0 degrees Celsius, like cold versions of the Old Faithful geyser in Yellowstone. A series of eight papers on this topic appeared in the journal “Science” today, and the laboratory has received incredible coverage making this story one of the biggest science stories of the year so far. For more information go to the Cassini website at

Last week the S19 sequence leads received word that the ST-5 launch,
scheduled for earlier in March, had slipped to March 14 and that part
of a DSN pass allocated to Cassini for data playback was required to support launch activities. If you ever wondered what the leads do with their time once the sequence is up and flying, this is part of it. Negotiations ensued with the DSN. The leads work very hard to preserve as much science data as possible. A replacement antenna was found that could be used by Cassini two days later on March 16. Even though the pass would be shorter than the original, it would be over a 70-meter antenna and could accommodate a higher data rate, thus preserving the science data. A new DSN allocation file was generated to reflect all the changes, and the leads sent commands to adjust spacecraft data rates where necessary. So then what happens? On Monday March 13, Cassini is notified that the launch has slipped to the 15th.
The good news is there is no additional impact to the Cassini passes. The
bad news, there is not enough time to revert back to the original passes so things will stay the way they are. As of Wednesday, March 15, the
launch has slipped again. ST-5 is now scheduled for departure on March 20. We have not yet been notified if there will be a new impact to the Cassini DSN allocation and if part of our pass that day will be needed for the launch.
If it is, the S19 leads will just keep on dancin’ till we get the data down.

Friday, March 10 (DOY 069):

The official input port for the S21 Science Operations Update Process
occurred today. Science Planning has merged the input products and
delivered them to SCO where they are being run through the end-to-end
pointing validation process by ACS. The Project Briefing and Waiver
Disposition Meeting is scheduled for Wednesday, March 22. The final
SOP Update product will handed off to the sequence leads on Friday, March 24, for the final development process.

S19 began executing today at roughly 5:45 PM Pacific time. S19 runs
for 42 days, concluding on April 22. During this sequence, there will be one targeted encounter, Titan 12, three Orbit Trim Maneuvers (OTM) are
planned, numbers 055, 056, and 057, 57 DSN tracks are scheduled, 15 of which will be over 70-meter stations, and 93.9 Gb of data will be downlinked.

An image of Enceladus was Astronomy Picture of the Day today.

Saturday, March 11 (DOY 070):

Operations Readiness Tests (ORT) were conducted Friday and today by
Radio Science (RSS) in preparation for the Titan 12 occultation, and the
mission’s first RSS Bistatic Titan Radar observation next week. Additional ORTs will be held on Sunday evening and Tuesday.

Monday, March 13 (DOY 072):

A go/no go meeting was held today for a Live Inertial Vector Propagator
(IVP) update to occur just after Titan 12 closest approach. Two Rhea
vectors need updating, both on DOY 80. A live update will execute on
that day and a live movable block will execute for Radio Science on DOY 77.

The decision to cancel OTM-55 was made at a Preliminary Navigation
Review today. Navigation, SCO, Uplink Operations, and Science Planning were all represented and agreed with the cancellation of the maneuver.

Tuesday, March 14 (DOY 073):

Instrument Operations/Multi-Mission Image Processing Laboratory (MIPL)
began testing today of the MIPL D35.0.2 software delivery. Testing should
take 2 or 3 weeks and then a Delivery Coordination Meeting will be scheduled to make the transition to operations.

Wednesday, March 15 (DOY 074):

An RWA bias was uplinked to the spacecraft to replace the bias not
performed when OTM-055 - scheduled to execute today - was cancelled.

The Aftermarket Process for the S23 sequence began today. This 5-week
process will address proposed changes that require re-integration of
the segments contained in the S23 sequence. An assessment package was sent out for review by S23 participants. Among the changes being tracked are those resulting from the planned release of a new reference trajectory on March 23. While difficult to characterize the total impact, we are aware
there could potentially be significant re-work necessary.

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.