NASA Cassini Significant Events 09/12/2012 – 09/18/2012
The most recent spacecraft tracking and telemetry data were collected on Sept. 19 by the Deep Space Network’s 34 meter Station 55 at Madrid, Spain. Except for the Cassini Plasma Spectrometer, which is off, and the failed Ultrastable Oscillator, the Cassini spacecraft is in an excellent state of health with all its subsystems functioning normally. Information on the present position of the Cassini spacecraft may be found on the “Present Position” page at: http://saturn.jpl.nasa.gov/mission/presentposition/.
Sequence Implementation Process teams worked on sequences that will go active in November and January. Effort is ramping up on development of S78, which will be uplinked in March. Cassini continued executing commands from the S75 sequence in flight.
Wednesday, Sept. 12 (DOY 256)
Today and again on Thursday, the Imaging Science Subsystem (ISS), Composite Infrared Spectrometer (CIRS), and the Visible and Infrared Mapping Spectrometer (VIMS) performed observations in the Titan monitoring campaign from a distance of about 1.5 million kilometers. The Cosmic Dust Analyzer (CDA) observed interstellar dust for 12 hours today and 13.5 hours on Thursday.
Thursday, Sept. 13 (DOY 257)
Cassini passed through apoapsis at just over twice the distance of Titan’s orbit from Saturn, having slowed to 6,641 kilometers per hour relative to Saturn. This marked the beginning of Orbit #172, which will have the same period and inclination as Cassini’s previous orbit, 21.3 days and 32.2 degrees.
A feature by a flight team member in the “Cassini Science League” discusses recently published findings that suggest that the weather on Titan might have exaggerated the moon’s oblateness. It may be found here: http://saturn.jpl.nasa.gov/news/cassiniscienceleague/science20120913/
Friday, Sept. 14 (DOY 258)
Taking full advantage of the apoapsis distance from Saturn and the spacecraft’s position outside the magnetosphere, CDA performed a 13-hour interstellar dust observation today and again on Sunday, then a shorter one on Tuesday.
The Attitude and Articulation Control Subsystem (AACS) team performed a Reaction Wheel Assembly (RWA) bias maneuver while off Earth-point. Thrusters stabilized the spacecraft so the RWA speeds could be adjusted. AACS then executed a Periodic Engineering Maintenance activity, which exercised the Engine Gimbal Actuators and the backup RWA.
Saturday, Sept. 15 (DOY 259)
The Magnetometer executed an 8-hour calibration while rotating the spacecraft about its X-axis and energizing the Science Calibration Subsystem coils to measure the physical alignment of individual MAG sensors.
Sunday, Sept. 16 (DOY 260)
The Deep Space Network (DSN) tracked Cassini on seven days this week using 34- and 70 meter diameter stations at the Goldstone Deep Space Communications Complex in the California desert.
Monday, Sept. 17 (DOY 261)
ISS performed another Satellite Orbit Campaign observation today and again on Tuesday. VIMS and CIRS spent 11 hours making a mosaic of the dark side of the rings.
The Spacecraft Operations (SCO) team uplinked real-time commands to modify one of Cassini’s telemetry modes, restoring nominal CDA data collection rates during Orbit Trim Maneuvers. SCO engineers watched telemetry showing the commands register and execute after a round-trip light time of 2 hours 56 minutes.
An image from the Titan monitoring campaign was featured today that shows a high-altitude vortex “Above Titan’s South.” The image may be seen here: http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4640
Ground-based image processing halted this morning because an incorrect time-tag was encountered in data headers. This was caused by a DSN telemetry system anomaly, which was corrected immediately and documented. Workarounds are expected to fully recover the affected ISS images and VIMS cubes later this week.
Tuesday, Sept.18 (DOY 262)
ISS began an 11-hour movie of the sunlit face of the rings at high phase, meaning mostly back-lit, in order to observe spoke-like features.
