Status Report

NASA Cassini Significant Events for 03/24/05 – 03/30/05

By SpaceRef Editor
April 1, 2005
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NASA Cassini Significant Events for 03/24/05 – 03/30/05

The most recent spacecraft telemetry was acquired today from the Goldstone tracking station. 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 rations/present-position.cfm .

Activities this week:

Science activities this week continued with the acquisition of Ultraviolet Imaging Spectrograph mosaics of Saturn’s inner magnetosphere, Imaging Science Subsystem (ISS) observations of Iapetus limb topography and geodesy, and a magnetospheric boundary campaign performed by the Magnetospheric and Plasma Science instruments.

Thursday, March 24:

Ion and Neutral Mass Spectrometer flight software normalization was performed last week on the Solid State Recorder (SSR).  The SSR has room for two different versions of flight software for each instrument, as well as for the software for the engineering computers.  Normalization means that both versions are equivalent.  This is actually the first time in flight that all instrument and engineering flight software copies are equivalent.

Last week, a Conference on Quality in the Space and Defense Industries (CQSDI) featured a session on mission success at JPL, and how mission operations assurance contributes to project reliability.   The talk began with a short session illustrating success highlights from 2004 and followed with a 90-minute panel breakout presentation on Cassini.  The presentation illustrated the Cassini mission operations assurance process and described how the Cassini flight team prepared for the critical mission events last year of Saturn orbit insertion and the Huygens Probe release and relay. Results from the Huygens mission were also shared along with lessons learned.  Attendees were encouraged to learn from the Cassini-Huygens experiences with respect to integrating mission operations assurance to increase reliability.

Systems Engineering gave a presentation on the Radio Science Subsystem (RSS) Inertial Vector Definition (IVD) process at today’s Cassini Design Team meeting.

Instrument Operations delivered version 2 of the Spacecraft, Planet, Instruments, C-matrix, and Events Kernel Generation Program, along with required documentation.

At a Program Change Control Board meeting it was decided to defer the delivery of Mission Sequence Subsystem version D11 for about two weeks from the current date of May 25 to allow for another re-delivery of the Inertial Vector Propagator (IVP) tool to fix an error that impacts RSSIVD functionality.  The first operational use of D11 was identified as S14 Science and Sequence Update Process, which begins on June 20, so the delay has no impact on operations use of the software.

Friday, March 25:

An image related to Huygens’s discovery of Luna Saturni (Titan) was Astronomy Picture of the Day today.

The Tethys Tweak Assessment/Approval Meeting was held today.  This is a rather complex issue with multiple options.  Before a decision could be made, more information was deemed useful for deciding on the possible science trades affecting data collection for both Tethys and Saturn. As time was still available before a final decision must be made, Project Management agreed to wait until next Tuesday’s Mission Planning Forum to enable the team to continue studying options.

Sequence Development continues for S11.  The Preliminary Sequence Integration and Validation 1 cycle one initial merged sequence products were published to the project file repository and are now available for review.

Today Navigation delivered the final orbit determination solution for Orbit Trim Maneuver (OTM) #19.  After that, evaluation files were published, reviewed, and cancellation of the Easter weekend maneuver was approved. Just a few short weeks ago on March 5, OTM #16 was cancelled.  The Significant Events report for that week discusses why cancellation is carefully considered, and last week’s report goes into some detail on the process for cancellation.

Monday, March 28:

Official port 2 occurred today for the S12 Science Planning update process. The team sequence files were merged and delivered to ACS for end-to-end pointing validation.

Tuesday, March 29:

A Cassini image of the crescents of Titan and Dione was Astronomy Picture of the Day today.

Events today included an Enceladus non-targeted flyby, Saturn periapsis, main engine cover close, a ring plane crossing, and a Cosmic Dust Analyzer (CDA) rocking downlink activity.

Downlinked data was lost over Madrid’s station DSS-63 today when station transmitter problems occurred.  CDA reported a loss of considerable data for the rocking downlink activity on day of year 88.  They did succeed, however, in partially reconstructing the impact rate based on the impact counters transmitted via housekeeping data.

At the Mission Planning Forum, the decision was made to proceed with the trajectory adjustment that will reduce the non-targeted Tethys flyby altitude from about 32,000 km to 1500 km, and to reduce the targeted Hyperion altitude from 1000 km to 500 km. There were pros and cons for the science that could be obtained with and without the change, but the consensus was that there was an overall improvement with the change. The cost for making the change is around 7 to 8 m/sec.

The Multi-Mission Image Processing Laboratory converted operations to version D33 software. This date was picked to minimize the impact upon optical navigation deliveries and scheduled processing requests.  The switch-over involved bringing down the automated processes, making database updates, changing pointers to the new D33 software set and restarting the processes.  The transition was successful and went very smoothly.

Wednesday March 30:

A Planetary Data System (PDS) peer review was held for a sample ISS team archive volume.  No major liens were identified.  The ISS team’s goal was to produce a usable, well-documented data set.  They met that goal extremely well.  PDS is currently organizing a review for a recently received CDA peer review volume.

Today’s on-board activities included RSS Titan gravity science, a Radio and Plasma Wave Science high frequency receiver calibration, and a reaction wheel biasing activity.

A Software Requirements and Certification Review for CDA flight software (FSW) version 10.0.0 was held today.  The FSW was approved pending support documentation modifications.  The new software will be uplinked to the spacecraft and a checkout performed in May of this year.  The purpose of this delivery was to implement updated parameters and algorithms for on-board data processing and data evaluation based on results of the early inner-Saturnian measurements.  This will calibrate the instrument based on to-date results, allowing for enhanced science return.

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.