Cassini Significant Event Report

For Week Ending 10/22/04

October 15th marked the 7-year anniversary of the launch of the Cassini spacecraft and Huygens Probe in 1997. The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Tuesday, October 19. 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 .

This week saw the conclusion of the 35 day S04 background sequence. Final activities included the uplink of Instrument Expanded Block files (IEBs) for the Imaging Science Subsystem (ISS), Cassini Plasma Spectrometer (CAPS), Radio and Plasma Wave Science (RPWS), Ultraviolet Imaging Spectrograph (UVIS), Composite InfraRed Spectrometer (CIRS), RADAR, and Visual and Infrared Mapping Spectrometer (VIMS), uplink of the S05 background sequence, turn-on of the Radio Science Subsystem (RSS) Ka-Band transmitter to assist in Iapetus Gm determination, and the execution of the Iapetus live Inertial Vector Propagator (IVP) update.

Science activity included movies of Saturn's rings by ISS, solar wind measurements by the Magnetospheric and Plasma Science (MAPS) instruments, a RADAR engineering test of diagnostic modes used on the instrument, and the start of the Iapetus distant flyby campaign for high-priority Gm Doppler data collection.

S05 began execution on Monday, October 18. Initial real time commanding included loading the VIMS and optical navigation IEBs to the SSR, execution of the ISS support imaging mini-sequence, a Reaction Control Subsystem thruster update, uplink of a RADAR trigger for the Titan-a flyby, and the turning on of the Magnetospheric Imaging Instrument (MIMI) collimator.

Initial science activities included observations to determine the composition of Saturn's stratosphere and troposphere as a function of latitude by the CIRS, ISS, UVIS, and VIMS instruments. The MAPS instruments continued their survey of the interplanetary medium and Saturn's outer magnetosphere. Toward the end of the week, a series of Iapetus observations began that will continue through next week.

The program conducted the Cassini-Huygens Probe Mission Critical Event Readiness Review on Tuesday, October 19. This was an external review convened to assess the program's preparations for a successful probe mission. The program presented accomplishments to date, plans for future work and open items covering flight products, navigation, operations planning, team and infrastructure support, spacecraft readiness, and strategic planning. The board was comprised of independent reviewers from JPL and other NASA agencies. The board report is not yet available but closing comments from the board were positive. The major open issue is the continued refinement of the Titan atmosphere model and its effect on the entry and descent parameters for the Huygens probe.

Preliminary port #1 occurred this week for the S09 Science Operations Plan (SOP) Update process. The instrument team files were merged and a report delivered to the teams identifying any problems with the merged product.

An assessment meeting was held on Wednesday as part of the S11 Aftermarket process. All requested changes to the sequence were reviewed. It appears that implementation of all requests may be accommodated within available resources.

Fourteen Sequence Change Requests (SCR) pertaining to tour sequence S06 were dispositioned last week. One was disapproved, two are pending and 11 were approved for implementation.

A series of articles was published in the journal Geophysical Research Letters last month detailing what scientists know to date about the surface, atmosphere and magnetic field of Titan. This information sets the stage for an analysis of new data soon to arrive from Cassini and the Huygens probe. The second largest moon in the solar system and the only one with a thick, methane-rich, nitrogen atmosphere, Titan intrigues scientists because of its resemblance to a young Earth. The atmospheres of both Titan and the early Earth were dominated by nearly the same amount of nitrogen, and the chemistry discovered on Titan could provide clues to the origins of life on our planet.

The RADAR team held the first of two operations rehearsals in preparation for next week's Titan-a encounter. The second will follow in a few days.

Cassini's radar will be used for first time to image the cloud-shrouded Titan when the spacecraft flies by at 1200 km above the surface. This is almost 300 times closer than the flyby in July of this year.

Live satellite interviews will be broadcast over NASA TV on October 22, live NASA TV commentary will be provided on the evening of the 26th, the day of the encounter, and news briefings will be provided on the 27th and 28th. NASA TV is available on the Web and via satellite in the continental U.S. on AMC-6, Transponder 9C, C-Band, at 72 degrees west longitude. The frequency is 3880.0 MHz. Polarization is vertical, and audio is monaural at 6.80 MHz. In Alaska and Hawaii, NASA TV is available on AMC-7, Transponder 18C, C-Band, at 137 degrees west longitude. The frequency is 4060.0 MHz. Polarization is vertical, and audio is monaural at 6.80 MHz. A full schedule of live news briefings is available on the NASA TV site at .

Titan atmosphere observations from the T0 flyby were reviewed at the Titan Atmosphere Model workshop held at NASA/Goddard Spaceflight Center on September 8/9. Following that workshop, modification of the Titan atmosphere model began and is currently being finalized by the Titan Atmosphere Model Working Group The updated model will be used for the Huygens entry and descent performance validation activities, and for the Cassini Orbiter low altitude Titan flyby strategy validation. A post-Ta workshop will be held on November 15 in Pasadena. This second workshop will focus on the analysis of the Ta data and relevant ground-based observations of Titan to further validate the Titan engineering model atmosphere updates for delivery to the Cassini/Huygens Project by 23 November.

The Planetary Data System (PDS) conducted a peer review of the RADAR Mosaics & MAPS high-level data products specification. The review panel included members of the RADAR team, PDS, and external science reviewers.

System testing for Mission Sequence Subsystem D10.4 began this week. D10.4 will provide an update to the Pointing Design Tool to support the RSS Inertial Vector Definition pointing capability needed for the S08 and S10 sequences, and for future occultation observations.

A delivery coordination meeting was held for the Instrument Operations tool Remote Terminal Interface Unit V3.2.

The Mission Support & Services Office (MSSO) reported that last week the Flight Control Team supported 11 DSN passes, and uplinked 33 command files to the spacecraft.

Mission Assurance convened a second Risk Team Meeting during the week to complete re-assessment of the risks identified for Probe Release and Probe Relay. The four items identified following the June Risk Team Meeting were dispositioned and evaluated. In addition, one risk was retired and two were consolidated with similar items. Recent changes to the Significant Risk List (SRL) were presented at the Probe Mission Critical Event Readiness Review.

Cassini Outreach and members of the Saturn Observation Campaign presented a school camp-out star party and Cassini talk for LILA - Lycee Internacional de Los Angeles students from kindergarten through 5th grade this week. The forty students plus their parents and teachers spent the days and nights learning about science, geology, and astronomy at Joshua Tree National Park.

A great picture of Saturn's South Pole was Astronomy Picture of the Day on October 18, 2004.

An article has recently been published via the Los Alamos National Laboratory News and Public Affairs Office regarding data being obtained by the Cassini Plasma Spectrometer (CAPS) and its findings. During Cassini's first pass over Saturn's rings, CAPS identified a previously unknown low-energy plasma trapped on the magnetic field lines threading the Cassini Division. The instrument is poised to provide scientists with a new level of understanding about Saturn's space environment, as well as clues about some of the space physics processes that operate more universally in the solar system. The CAPS team involves scientists and engineers from 14 institutions and six countries around the world. The CAPS Principal Investigator is based at the Southwest Research Institute in San Antonio, Texas.

Extensive information on the Cassini-Huygens mission including an electronic copy of the press kit, press releases, fact sheets, status reports, briefing schedule and images, are available on the Internet at .