Emily LakdawallaJun 20, 2007

Fine-tuning Cassini's orbit

I found several items of interest in the latest "Cassini Significant Events" report. These reports are issued weekly by the Jet Propulsion Laboratory and constitute a blow-by-blow description of Cassini's activities, as well as the plans for future activities, much like the status updates that JPL issues for the rovers.

Here's the first interesting item:

Sunday, June 10 (DOY 161)

Orbit Trim Maneuver (OTM) #115 was performed today. This is the approach maneuver setting up for the Titan 32 encounter on June 13. The reaction control subsystem burn began at 6:30pm PDT. Telemetry immediately after the maneuver showed the burn duration was 25.5 seconds, giving a delta-V of 0.036 m/s. This maneuver was targeted to lower the upcoming T32 flyby altitude by 10 km, from 975 to 965 km. Navigation analysis showed that lowering the T32 closest approach would save about 2.5 m/sec in downstream maneuver sizes, and would bring the trajectory back closer to the reference trajectory. All subsystems reported nominal performance after the maneuver.

Here's the next item, from the same day:

A new background sequence, S31, began execution on board the spacecraft today. The sequence will run for 33 days, concluding on July 14. During that time there will be two targeted encounters of Titan, twelve non-targeted flybys of Mimas, Atlas, Prometheus, Epimetheus, Methone, Tethys, Enceladus, and Rhea, and five maneuvers, numbers 116 through 120, are scheduled for execution.

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