From: Jet Propulsion Laboratory
Posted: Thursday, August 30, 2012
The most recent spacecraft tracking and telemetry data were collected on Aug. 29 by the Deep Space Network's 70 Station 14 in the California desert at Goldstone. Except for the Cassini Plasma Spectrometer, which is off, and the inoperative 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/ .
Optical Remote Sensing (ORS) observations of Saturn dominated this week's spacecraft activities while it was near apoapsis. The spacecraft rotated under reaction-wheel control, taking data and then pointing to Earth six times to communicate with Cassini engineers and scientists via the Deep Space Network (DSN). On four of those tracking periods, the DSN participated in Operational Readiness Tests to prepare for a Radio Science coherent-mode Saturn atmospheric ingress occultation experiment that will execute next Sunday.
Wednesday, Aug. 22 (DOY 235)
The Composite Infrared Spectrometer (CIRS) completed an 11-hour observation to map Saturn's atmosphere in the far-infrared part of the spectrum.
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.
Thursday, Aug. 23 (DOY 236)
The Imaging Science Subsystem (ISS) and CIRS traded off observing Saturn to study its winds and atmospheric composition, respectively.
Cassini passed through apoapsis today at 2.6 million kilometers from Saturn, having slowed to 6,640 kilometers per hour relative to the planet. This marked the start of orbit #171, which has a period of 21.3 days around Saturn and an inclination of 32.2 degrees.
Friday, Aug. 24 (DOY 237)
The spacecraft performed an 8-hour roll to calibrate the Magnetometer instrument sensors.
Saturday, Aug. 25 (DOY 238)
The S75 background sequence, which was uplinked last week, began its 10-week control of the spacecraft and instruments. Work by the Sequence Implementation Process team on this command sequence had begun in March 2012.
The Ultraviolet Imaging Spectrograph (UVIS) spent 16 hours mapping Saturn in the extreme- and far-ultraviolet (EUV and FUV), then CIRS began its infrared mapping activity to measure trace gases and isotopes in Saturn's atmosphere.
Sunday, Aug. 26 (DOY 239)
CIRS began another 11-hour compositional mapping activity.
Monday, Aug. 27 (DOY 240)
At the end of the CIRS observation, ISS observed Saturn's winds for two hours. AACS then performed another RWA bias (momentum-management) maneuver. This time the DSN was tracking the spacecraft, so the Cassini Navigation team was able to measure the slight delta-V imparted by the thrusters.
The image "Night Side Rings" was featured today. It shows a spectacular view of the night side of Saturn, whose northern hemisphere can be seen illuminated in ringlight, and shows the rings illuminated from the opposite side. The image can be viewed here: http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4623
Tuesday, August 28 (DOY 241)
After another ISS observation of Saturn's winds, the ORS science instruments made a 90-minute observation in the campaign to monitor Titan's atmosphere and clouds. UVIS then conducted another EUV-FUV map of Saturn.
Visit the JPL Cassini home page for more information about the Cassini Project: http://saturn.jpl.nasa.gov/
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