Cassini Significant Events 10/31/07 - 11/06/07

November 8, 2007

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired on Tuesday, Nov. 6, from the Madrid 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" page at

Wednesday, Oct. 31 (DOY 304):

The S39 Aftermarket process completed today. The Science Operations Plan Update process for this sequence will kick off on Wednesday, Nov. 7.

Submodule 39 on SSR-A was turned off Oct. 31, 2007. This submodule failed in December, 2006, and has been causing some minimal level of data corruption since then. The ability to isolate faulty memory submodules in the SSR is a new capability available in the CDS V10 flight software that was installed on the spacecraft in October.

The S35 background sequence began execution today. The sequence will run for 44 days, concluding on Dec. 14. During that time there will be two targeted flybys of Titan, T37 and T38, eight non-targeted encounters, one each of Rhea, Pandora, Pan, Calypso, Telesto, and Mimas, two of Epimetheus, and orbit trim maneuvers numbered 132-138.

The S35 sequence began execution while the spacecraft was upstream of Saturn's bow shock. To take advantage of this, the Magnetospheric and Plasma Science (MAPS) instruments began a 63-hour campaign to monitor solar wind conditions in the vicinity of Saturn. At the same time the Cosmic Dust Analyzer (CDA) measured the properties of dust outside the Saturnian magnetosphere. Later in the day Imaging Science performed a one-hour observation of the F ring as part of long term temporal monitoring of this ring.

Last week Cassini Outreach participated in the Mt. Wilson Girl Scout Council's Family Science Festival held at Monrovia High School on Sunday, Oct. 28. Around 1,100 people from Brownies to Seniors to parents to troop members rotated through several dozen demonstrations, activities, and talks about science. 

Thursday, Nov. 1 (DOY 305):

Orbit Trim Maneuver (OTM) #132 was performed today. This is the apoapsis maneuver setting up for the Titan 37 encounter on Nov. 18. The main engine burn began at 10:00 AM PDT. Telemetry immediately after the maneuver showed the burn duration was 6.01 seconds, giving a delta-V of 0.967 m/s, as planned. All subsystems reported nominal performance after the maneuver.

Friday, Nov. 2 (DOY 306):

Cassini spacecraft personnel participated in a meeting today with Div. 35 engineers to discuss main engine (ME) cover cycles. The current in-flight limit for this consumable is 37 cycles. To date, 35 of the 37 have been used. Completing the prime mission with the current cover use policy will require approximately 40 cycles and the proposed Extended Mission will add about 22 more cycles. Cover performance has been nominal, the risk of continued cover use is believed to be low compared to the risk of dust hazards without the cover, and a cover anomaly contingency plan is in place. It was decided to waive the limit, continue using the cover on an as-needed basis, and carefully monitor its performance.    

The Titan Orbiter Science Team held an integration meeting today to complete the high-level integration for all of the Titan flybys in the proposed Extended Mission (XM). The Satellite Orbiter Science Team will be holding a similar integration meeting on Nov. 16 to integrate the Enceladus flybys in the XM.

As part of the normal development process for S36, it was determined that Radio Science and RADAR would like to perform a test in the Integrated Test Laboratory (ITL) for the Titan 39 flyby on Dec. 20. The test began today and will conclude on Nov. 7.

Sunday, Nov. 4 (DOY 308)

On DOY 308, Radio Science (RSS) performed a unique radio-science-in-reverse demonstration. During normal Radio Science experiments that are based on a one-way radio signal, the downlink signal from the spacecraft is monitored as the spacecraft passes behind some target of interest - Saturn's rings, the atmosphere of Titan, or the atmosphere of Saturn itself - as viewed from Earth. In this experiment, an S-band signal at 2040 MHz was transmitted from DSS-24 and received on-board the Cassini spacecraft by the European Space Agency's Probe Support Avionics (PSA). These are the same receivers that were used to communicate with the Huygens Probe as it descended towards and landed on the surface of Titan. The data, retrieved through telemetry packets, showed the PSA to be working well with potential for actual radio science investigations.

The Huygens PSA on Cassini consists of two receivers operating at different S-band frequencies and at opposite polarizations. Only one of the two channels utilized a Rubidium-based Receiver Ultra-Stable Oscillator (RUSO) as a frequency reference. The RUSO-based channel received the uplink signal from DSS-24 at Goldstone, CA, which was transmitted at 20 kW uplink power at ~ 2040 MHz. There was no tuning of the uplink; a fixed, carefully selected frequency was transmitted. The sequence of events was designed such that the command to power-on the RUSO and PSA was coincident with the arrival of the uplink signal. This allowed the observation of the warm-up process. The entire activity lasted for one hour.

This reverse occultation demonstration could pave the way toward future occultation observations with signal-to-noise ratios hundreds of times greater than traditional occultation observations, allowing Cassini scientists to probe deeper into the atmosphere of Saturn and Titan, through the denser regions of Saturn's B ring, and during solar conjunctions.

Monday, Nov. 5 (DOY 309)

A kick-off meeting was held today for a Rhea-Saturn live update for DOY 320-321. After analysis and review by representatives from the Composite Infrared Spectrometer, Radar, Ultraviolet Imaging Spectrograph (UVIS), and Science Planning teams, it was determined that pointing was still within tolerance and the update would not be needed.

Tuesday, Nov. 6 (DOY 310)

The S38 Science Operations Plan update official port occurred today. This process will complete on Wednesday, Nov. 21.

As part of the "SCIENCE 101- A Science Lecture Series For The Non-Scientist", a member of the Cassini UVIS instrument team gave a presentation today in Von Karman Auditorium at JPL on exploring the icy moons of Jupiter and Saturn.

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