Status Report

NASA Cassini Significant Events for 06/23/05 – 06/28/05

By SpaceRef Editor
July 1, 2005
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NASA Cassini Significant Events for 06/23/05 – 06/28/05

The most recent spacecraft telemetry was acquired Wednesday 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 .

Activities this week:

The entire suite of Magnetospheric and Plasma Science (MAPS) instruments conducted surveys to measure the properties of interactions between Titan and its torus. Measurements included the composition, density, spatial, and temporal variation in the torus region when Titan is not close by and perturbing it.

The Magnetospheric Imaging Instrument (MIMI) imaged the dynamics of the inner magnetosphere, and the Composite Infrared Spectrometer (CIRS) mapped Titan to obtain measurements of nitriles, hydrocarbons, and carbon dioxide as a function of latitude and emission angle.

At this time the Radio and Plasma Wave Science (RPWS) instrument is on a campaign to obtain the highest resolution observations of Saturn Electrostatic Discharges (SED) within a distance of 6 Saturn radii. Results will help to verify the source as lightning, or provide evidence that the SEDs could be of some other origin such as Saturn’s rings.

The fourth of eight Radio Science Subsystem (RSS) occultation observations occurred this week. Skip ahead to June 26 for specific details of that and other science events for that day.

Thursday, June 23 (DOY 174):

The live movable block mini-sequence was uplinked today over the Goldstone tracking complex. Confirmation has been received from the spacecraft that the program has registered properly on board. The mini-sequence will begin execution on Sunday, June 26.

A member of the Spacecraft Operations Office (SCO) gave a Cassini talk to 30 members of the Altadena Rotary Club in Altadena, California.

Friday, June 24 (DOY 175):

Delivery Coordination Meetings were held today for Navigation Software T2, and Maneuver Automation Software (MAS) version 5. This version of Navigation Software includes the move to Red Hat 8.0 & Enterprise 4 Linux, MAS/MOPS changes, multi-mission changes and new utilities. The MAS release provides needed capabilities to support current and future OTMs.

The S12 Preliminary Sequence Integration and Validation 1 sequence change request approval meeting was held today.

A command to enable RPWS Sounder Operations was uplinked to the spacecraft. Sounder operations were confirmed to have begun around 17:50 Spacecraft Event Time (SCET), about a one-way light time after the command was sent.

RSS personnel participated in an Occultation Operational Readiness Test (ORT) today. This is the last test prior to the occultation observations that will occur on Sunday.

Sunday, June 26 (DOY 177):

Today there were non-targeted flybys of Tethys, Pan, and Telesto.

The RSS Saturn/Rings Ingress and Egress occultation completed successfully this evening. The occultation occurred over three antennas at the Goldstone DSN complex and was the fourth of eight occultation observation periods planned between May and September.

This was one of the best diametric occultations primarily because of the high elevation angles at the tracking station leading to better Signal-to-Noise-Ratio (SNR) and less perturbations of the signal phase by Earth’s atmosphere. In addition, the occultation was entirely covered by what’s considered to be the best Ka-band receiving antenna, DSS-25, for both ingress and egress. Based on real-time monitoring of signal levels, the limb track maneuver seemed to have executed well. This will be verified once the team receives the ACS reconstructed C-Kernel.

Additional observations included RPWS measurements at the Ring Plane Crossing to determine the equatorial dust flux and scale height as a function of radial distance, while also obtaining high-resolution measurements of plasma waves at the magnetic equator. The Imaging Science Subsystem (ISS) obtained an ansa movie of the outer B ring edge and performed an azimuthal scan of the Cassini Division and Encke Gap, and the Ultraviolet Imaging Spectrograph (UVIS) obtained a high-resolution radial profile of the B ring optical depth by making measurements of the star 26 Tau as it passed behind the B Ring. Finally, all the Optical Remote Sensing instruments performed joint studies of the rings at zero phase angle.

Monday, June 27 (DOY 178):

The main engine cover was successfully opened in preparation for Orbital Trim Maneuver (OTM) 25. The cover has been closed since April 30. SCO also performed an Attitude Control System reaction wheel bias.

Commands were sent to the spacecraft by Uplink Operations to set up and perform the Visual and Infrared Mapping Spectrometer (VIMS) S12 instrument expanded block SSR load #2, to clean up after this operation, and to disable RPWS Sounder Operations.

RSS performed a Saturn Gravity Science experiment today.

Tuesday, June 28 (DOY 179):

A Planetary Data System archive peer review was held for the Ion and Neutral Mass Spectrometer (INMS) and RADAR instruments. The review went well with only minor liens identified. Archive software interface specification documents for the Cosmic Dust Analyzer (CDA), INMS and RADAR are in the signature cycle.

A press release is now available regarding the lake-like feature recently observed on Saturn’s moon Titan. Cassini captured a series of images, released today, showing a marking, darker than anything else around it. It is remarkably lake-like, with smooth, shore-like boundaries unlike any seen previously on Titan. The site has been identified as the best candidate seen so far for a liquid hydrocarbon lake on Titan. For more information link to .

Instrument Operations successfully completed analyzing the results of the ISS flight software (FSW) checkout performed on June 14. A sequence to permanently switch to FSW version 1.4 has been built, reviewed and approved. Negotiations are underway to upload it in early July in time to be used for the Enceladus encounter.

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.