From: Jet Propulsion Laboratory
Posted: Saturday, January 12, 2013
Cassini is orbiting Saturn with a period of 13.3 days in a plane inclined 53 degrees from the equator. The most recent spacecraft tracking and telemetry data were collected on Jan. 9 by a 34 meter Deep Space Network station at Canberra, Australia. Except for some science instrument issues described in previous reports, the spacecraft continues to be in an excellent state of health with all of its subsystems operating 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/ .
Cassini scientists selected ten outstanding science highlights from 2012. They are presented here: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20130103/ .
Wednesday, Jan. 2 (DOY 002)
The Imaging Science Subsystem (ISS) created a 13.5 hour movie of the dark face of the rings at a high phase angle to search for periodicities in the spokes. On Earth, the Deep Space Network (DSN) participated in operations readiness tests today and will again on Thursday, preparing for the Radio Science occultation experiment on Jan. 5.
Thursday, Jan. 3 (DOY 003)
The Visible and Infrared Mapping Spectrometer (VIMS) and the Ultraviolet Imaging Spectrograph (UVIS) pointed at the southern polar region of Saturn, which is currently under the darkness of winter, to study the planet's aurorae. The Composite Infrared Spectrometer (CIRS) then undertook regional mapping of the southern polar vortex to measure temperatures in this feature.
Friday, Jan. 4 (DOY 004)
VIMS followed CIRS' vortex mapping by taking mosaics of the same region on Saturn that will be actively probed in tomorrow's Radio Science atmosphere egress occultation experiment. UVIS then observed the Sun being occulted by Saturn to probe the planet's atmosphere. With the Sun safely behind the planet, ISS was free to observe the atmosphere at very high phase angles, in which the forward-scattered light highlights small particles and hazes.
Today and on two other days this week, the Attitude and Articulation Control Subsystem (AACS) team executed Reaction Wheel Assembly bias maneuvers to adjust wheel speeds while thrusters stabilized the spacecraft. The Navigation team relied on telemetry played back later, rather than real-time Doppler data, to model the thrusters' effect on the trajectory.
Saturday, Jan. 5 (DOY 005)
With Cassini's high-gain antenna pointed towards Earth, the Radio Science Subsystem (RSS) team recorded the signals from the spacecraft as it emerged from behind Saturn's limb during an egress-only atmospheric occultation experiment. The Deep Space Network's 18 kilowatt transmitter penetrated Saturn's atmosphere, providing a reference frequency for Cassini to generate its downlink signals at S-band, X-band, and Ka-band radio frequencies.
ISS pointed its cameras to Titan to look for meteorological activity as part of the long-term Titan monitoring campaign. VIMS then observed the refraction and attenuation of starlight through Saturn's atmosphere as it observed two stars, gamma Eridani and L2 Puppis, being occulted by Saturn. Between the occultations, CIRS targeted a storm region at 37 degrees north latitude with its mid-infrared detectors. The day's activities were completed with CIRS training its far-infrared detector on the same latitude that RSS observed during the atmospheric occultation egress. One of the goals of this joint RSS/CIRS campaign is to determine the helium abundance in Saturn's atmosphere.
Cassini passed through periapsis going 41,694 kilometers per hour with respect to Saturn, at about 388,000 kilometers above the cloud tops.
Sunday, Jan. 6 (DOY 006)
VIMS imaged the northern polar region of Saturn to characterize the curious northern hexagon, with ISS riding along and returning some remarkable images (raw images may always be found at http://saturn.jpl.nasa.gov/photos/raw). UVIS, and subsequently VIMS, then focused again on the Saturnian aurorae, this time observing the northern auroral zones for a total of nine hours.
Monday, Jan. 7 (DOY 007)
During a brief observation, ISS imaged Saturn's limb in a geometry that complemented the images obtained three days earlier when Cassini was on the far side of Saturn. Finally, VIMS mapped out the northern mid-latitudes.
Commands were sent today that will execute on Wednesday to conduct a high-voltage test on the Magnetospheric Imaging Instrument, increasing the gain in its Ion and Neutral Camera. Another command was sent to update the AACS Attitude Control Error Integrator in real time. The commands were confirmed on board the spacecraft after a round-trip light time of two hours forty-eight minutes.
The Magnetometer Subsystem carried out a calibration by rolling the spacecraft about its Z axis while Cassini was communicating with the DSN.
An image of Enceladus, its face illuminated in Saturn-shine, was released today showing its south polar jets as they fall into the darkness of winter. "Sunset on the Jets" may be viewed here: http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4712
Tuesday Jan.8 (DOY 008)
The Cosmic Dust Analyzer (CDA) made a series of observations in the exogenous dust campaign, measuring particles coming from elsewhere in the solar system. These observations required the spacecraft to roll about its Z-axis while pointing its high-gain antenna to Earth. The first in a series of three such observations, it lasted 37 hours.
A feature released today shows how hydrocarbon ice, mixed with some "air", may be floating on a liquid hydrocarbon sea on the surface of Titan. It may be found here: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20130108/
Visit the JPL Cassini home page for more information about the Cassini Project: http://saturn.jpl.nasa.gov/
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