Cassini is orbiting Saturn with a period of 13.3 days in a plane
inclined 53 degrees from the equatorial. The most recent spacecraft
tracking and telemetry data were collected on Jan. 30 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.
Sequence Implementation Process teams continued working on the
ten-week command sequences S78 and S79, which will go active on
Cassini in March and June respectively, and planning continued for the
2016 start of Cassini's F-ring and Proximal Orbits phase. Meanwhile,
commands from the on-board S77 sequence controlled the spacecraft's
activities in flight. Information on the present position and speed of
the Cassini spacecraft may be found on the "Present Position"
page at: http://saturn.jpl.nasa.gov/mission/presentposition/.
Wednesday, Jan. 23 (DOY 023)
The Cosmic Dust Analyzer completed a 36 hour observation of dust
orbiting Saturn in the retrograde direction.
Thursday, Jan. 24 (DOY 024)
A calibration of Cassini's Y-thrusters took place today. This annual exercise allows the Navigation and Attitude Control teams to validate the force-balance of the coupled Y-thruster pairs. Preliminary navigation results were as expected. This is an important measurement because Reaction Wheel Assembly (RWA) bias maneuvers using the Y-thrusters are performed frequently, and are not tracked by the Deep Space Network (DSN). Three such RWA bias maneuvers were done this week, including one today right before the calibration.
The Visible and Infrared Mapping Spectrometer (VIMS) began making
a 12 hour mosaic of the dark side of the rings. On most occasions such
as this, optical remote-sensing observations led by one instrument
include "ride-along" data-taking by other optical
instruments since their boresights are co-aligned.
After 14 years of exceptional management of the Cassini-Huygens
Program, Bob Mitchell retired today; Dr. Earl Maize has returned
to become the new Program Manager. Maize managed the Cassini
Spacecraft Operations Office through assembly and test, launch and
early cruise, and later served as the Deputy Program Manager up
through the Huygens touchdown on Titan.
Friday, Jan. 25 (DOY 025)
The Imaging Science Subsystem (ISS) performed an observation in the satellite orbit campaign, then the Navigation team used ISS to take five images of Saturn's satellite Rhea against background stars for optical navigation purposes. The Composite Infrared Spectrometer (CIRS) began a 22 hour observation to measure oxygen compounds (H2O, CO2) in Saturn's stratosphere.
Cassini passed through apoapsis, having coasted just over 1.7
million kilometers "up" from the planet and slowing to
10,892 kilometers per hour relative to Saturn. This marked the
beginning of Cassini's orbit #180.
Saturday, Jan. 26 (DOY 026)
VIMS began a 13.5 hour observation of the star R Lyrae as it was
being occulted by the rings.
Sunday, Jan. 27 (DOY 027)
Sunday, Jan. 27 (DOY 027)
ISS began a 13 hour low-resolution movie of the F ring. DSN
stations in Canberra, Australia and Goldstone, California participated
in two operations readiness tests today, and two more on Monday,
preparing for the radio science ring and Saturn atmosphere occultation
experiment coming up on Thursday.
Monday, Jan. 28 (DOY 028)
Today and again on Tuesday, ISS created movies of the dark face of the rings lit from behind at high phase, in order to search for periodicities in the spokes. CIRS then began an eight hour observation of the main rings in order to obtain compositional information.
An image Cassini took of Titan from 1.8 million kilometers away,
showing surface features and the high polar vortex, was featured
today:
http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4722
.
Tuesday Jan. 29 (DOY 029)
The Magnetometer executed a calibration by rolling the spacecraft about its Z axis during a DSN communications session.
The flight team processed Orbit Trim Maneuver (OTM) #339 and approved its command file for uplink tonight; it will execute on Jan. 30.
OTM #339 will be a main engine burn of about 1.66 m/s targeting the Titan flyby T89 occurring on February 16 (PST).
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