Cassini Significant Events 11/09/06 - 11/15/06

November 17, 2006

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired on Wednesday, Nov. 15, from the Goldstone 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" web page at .

Thursday, Nov. 9 (DOY 313):

Cassini passed by Enceladus today at an altitude of 91,500 km. Additional non-targeted flybys included Tethys and Calypso.

Orbit Trim Maneuver (OTM) #80 was performed today. This is the first of three maneuvers setting up for the Titan 21 encounter on Dec. 12. The main engine burn began at 7:45 AM PDT. Telemetry obtained after the maneuver showed a burn duration of 22.7 seconds, giving a delta-V of approximately 3.6 m/s, as designed. All subsystems reported nominal performance after the maneuver.

The Spacecraft Operations Office (SCO) held a tabletop walkthrough today. The team went through the Deep Under-voltage System Fault Protection response. The purpose was to provide training for the team in understanding how the spacecraft responds in a deep UV scenario, and the final spacecraft states after safing completes. This activity is part of SCO ongoing refresher training, and operational readiness tests to exercise and train new and "old" members of the spacecraft team.

The DSN/Goldstone Cassini track over station DSS-14 was cut short today in order to support an MGS request for additional 70m coverage. However, the DSN schedulers were able to obtain additional time for Cassini over DSS-15 from 09:45 to 18:45. Due to the differences in antenna capabilities, a real time command was uplinked to change the telemetry mode compatible with the change from DSS-14 to DSS-15. Additional time was also obtained for Cassini on DOY 315, this time for additional DSS-14 coverage from 09:30 to 13:05. A command will be sent on that day to implement the telemetry mode change from DSS-15 to DSS-14.

Last week it was reported that Cassini gave up DSN coverage over DOY 311 as a result of the MGS anomaly. The result was loss of science and engineering data from DOY 311 for about 4 hours and 35 minutes, plus an additional loss over DSS-65 on DOY 312 due to rain in Spain. The impact to science is a loss of a portion of a Composite Infrared Spectrometer ring observation, a loss of an Imaging Science Subsystem Ring observation, loss of some real time Magnetospheric and Plasma Science data, and loss of the Radio and Plasma Wave Science (RPWS) whistler observation. This particular RPWS observation included intentional transitions to and from reaction control subsystem control instead of being on reaction wheels. A whistler is caused by a lightning stroke. It emits a low frequency emission that allows RPWS to remotely sense plasma density. Normally, plasma density can only be sensed by RPWS in the vicinity of the instrument on board the spacecraft.

Friday, Nov. 10 (DOY 314):

The Caltech Pre-College Science Initiative completed its yearlong evaluation of the Cassini language arts unit "Reading, Writing & Rings" (RWR). The evaluation noted that teachers find the materials to be of high quality and that RWR improved attitudes toward science and reading. However, the current high stakes testing atmosphere in classrooms makes implementation difficult. The team that produced RWR will work to address teachers' needs and the realities of schooling to improve implementation and explore RWR uses outside formal educational settings such as after school settings, museums, and amateur astronomy groups.

Monday, Nov. 13 (DOY 317):

An image of a hurricane-like storm over Saturn's south pole is Astronomy Picture of the Day today.

The final approval meeting was held today for S26. The sequence will be uplinked on Nov. 21, and will begin execution on Friday, Nov. 24.

Tuesday, Nov. 14 (DOY 318):

The topic at the Mission Planning Forum this week was Titan minimum altitudes during extended mission. Existing models and tumble densities have been extrapolated for the extended mission to get a feel for what altitudes will be acceptable, versus the 1000 km baseline that was delivered to the tour designers for study purposes. This is likely to be an ongoing topic of discussion in future meetings.

The patch to Cosmic Dust Analyzer instrument flight software version 10.4 will run onboard the spacecraft today and tomorrow. Results will be reported over the next several weeks.

A delivery coordination meeting was held today for an upgrade to the Cassini Archive Tracking System (CATS). This version of CATS contains a number of changes and new capabilities. The driver for this delivery stems from the need to gather more information about what is being archived and how much. This delivery also includes some changes requested by the users.

Wednesday, Nov. 15 (DOY 319):

The S29 Science Operations Plan Update process kickoff meeting was held today. The process will run for approximately eight weeks and will conclude on January 12 of 2007.

An AACS friction test on the prime reaction wheels, numbers one, two, and four, was run onboard the spacecraft today. In this test, performed every three months, the wheels are spun up to 900 rpm in both directions and timed as they are allowed to run down to zero. The longer the rundown time, the better. For this exercise, AACS updated the custom telemetry schedule to obtain data at a 1 Hz frequency to support characterization in the frequency domain.