Cassini Significant Events 08/29/2012 – 09/04/2012

The most recent spacecraft tracking and telemetry data were collected on Sept. 4by the Deep Space Network's 70 meter Station 63 at Madrid, Spain. 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/.

Sequence Implementation Process teams continued working on the ten-week command sequences S76 and S77, which will go active in November and January respectively. Ground-based testing proceeded for the A8.9.0 version of Attitude and Articulation Control Subsystem (AACS) flight software, which will be installed on the spacecraft in December. Meanwhile, Cassini continued executing S75 commands in flight.

Wednesday, Aug. 29 (DOY 242)

The Magnetospheric and Plasma Science (MAPS) in-situ instruments undertook a survey of conditions in Cassini's immediate environment.

A file of twenty commands was sent to update the spacecraft's Inertial Vector Propagator to refine pointing vectors to Saturn and Enceladus. Another thirteen commands were sent from a file to adjust the execution time of a Live Moveable Block (LMB) of commands on Cassini. These were all in support of the science activities coming up on DOY 246.

Thursday, Aug. 30 (DOY 243)

The Composite Infrared Spectrometer (CIRS), the Imaging Science Subsystem (ISS), the Visible and Infrared Mapping Spectrometer (VIMS), and the Ultraviolet Imaging Spectrograph (UVIS) completed the second of two coordinated campaigns to map out the winds and composition of the Saturnian atmosphere.

Friday, Aug. 31 (DOY 244)

VIMS and ISS completed an observation in the Titan monitoring campaign, then the Navigation Team took five ISS images of Enceladus against the background stars for optical navigation purposes. CIRS and the other Optical Remote Sensing instruments made an 8.6-hour observation of Saturn's south polar aurora for compositional mapping.

The 2012 Cassini Scientist for a Day essay contest, for students in grades 5-12, opened today. Details are available here: http://saturn.jpl.nasa.gov/scientistforaday/

Saturday, Sept. 1 (DOY 245)

CIRS mapped Saturn's atmosphere in the far-infrared, after which UVIS mapped it in the extreme- and far-ultraviolet parts of the spectrum.

The Radio Science team conducted a Saturn Gravity Science Enhancement observation using the X-band (8 GHz) and Ka-band (32 GHz) downlink radio signals. The Deep Space Network (DSN) provided the stable uplink frequency for reference.

Sunday, Sept. 2 (DOY 246)

The Radio Science team carried out a coherent-mode Saturn atmosphere ingress occultation experiment. With Cassini's Deep Space Transponder locked onto the DSN uplink for reference in the absence of an operable on-board ultra-stable oscillator, DSN stations on two continents - two 70 and two 34 meter diameter dishes - simultaneously tracked the spacecraft as it passed behind Saturn's limb. Under control of the LMB whose timing had been updated on Wednesday, the spacecraft turned to track the refracted location of Earth from behind Saturn's upper atmosphere. The S-band (2 GHz), X-band, and Ka-band downlink signals comprised the Radio Science data that were captured and recorded for later investigation. UVIS then observed a solar occultation by Saturn's atmosphere.

Monday, Sept. 3 (DOY 247)

ISS observed the Enceladus plume for two hours at a distance of 370,000 kilometers while it was back-lit by the Sun.

Cassini passed through periapsis going through the outer E ring at a speed of 49,990 kilometers per hour relative to Saturn.

UVIS observed the star Beta Canis Majoris as it emerged from occultation by Saturn, and then watched the star Zeta Puppis being occulted by the rings. VIMS then executed another high-resolution regional map of Saturn, focusing on northern mid-latitudes.

An image was featured today showing Saturn's two-tone moon Iapetus with a "Big Crater Down South." It may be seen here: /resources/15637.

Tuesday, Sept. 4 (DOY 248)

The MAPS instruments undertook another survey, then UVIS performed a 4-hour calibration using the star Spica. Finally, ISS, CIRS and VIMS carried out another observation in the Titan monitoring campaign from a distance of two million kilometers.

Rotating Cassini under control of its Reaction Wheel Assemblies (RWA) to point the instruments for all the science observations this week required executing three AACS RWA bias maneuvers for momentum management on various days this week.