News | March 20, 2013
Cassini Significant Events 03/13/2013 - 03/19/2013
Cassini is orbiting Saturn with a twelve-day period in a plane inclined 57 degrees from the planet's equatorial plane. The most recent spacecraft tracking and telemetry data were collected on March 20 by a 34-meter Deep Space Network station at Goldstone, California. 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 frequently turns, under control of its electrically driven Reaction Wheel Assemblies (RWA), to point its optical remote-sensing instruments as detailed below. Meanwhile as if behind the scenes, Cassini's suite of in-situ direct-sensing instruments are almost always taking data on fields and particles in the spacecraft's immediate environment regardless of its orientation.
Wednesday, March 13 (DOY 072)
The Imaging Science Subsystem (ISS) performed an observation in the Satellite Orbit Campaign, looking at small satellites near Saturn. ISS, the Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS) then performed another observation in the Titan monitoring campaign from 2.5 million kilometers away. VIMS squeezed in two 2-minute Saturn storm-watch observations, the first of six such observations this week. Another Satellite Orbit observation executed on Monday.
Thursday, March 14 (DOY 073)
ISS observed the orbit of Aegeaon, the source moon of the faint G ring, at low phase-angle illumination for eleven hours. ISS, CIRS and VIMS then performed another observation in the Titan monitoring campaign; the distance to Titan had increased somewhat.
Observations Cassini made of Jupiter in late 2000 while en route to Saturn are featured today in an analysis of “hot spots” caused by atmospheric waves.
Friday, March 15 (DOY 074)
CIRS created a 13.5-hour mid-infrared map of Saturn to determine upper troposphere and tropopause temperatures. The Attitude and Articulation Control Subsystem team then exercised the backup RWA (RWA-3) while the hydrazine-powered Reaction Control Subsystem (RCS) thrusters steadied the spacecraft.
Saturday, March 16 (DOY 075)
Cassini passed through apoapsis, having coasted 1.5 million kilometers "up" from the planet while slowing to 12,413 kilometers per hour relative to Saturn. This marked the beginning of Cassini's orbit #184.
The Cosmic Dust Analyzer (CDA) performed a fifteen-hour observation in the campaign to characterize dust that orbits Saturn in a retrograde direction. The Magnetometer (MAG) then executed a calibration using its Science Calibration Subsystem, which includes a magnet coil on the spacecraft.
Orbit Trim Maneuver (OTM) 345, the apoapsis maneuver targeting to the Titan T90 encounter on April 5, was performed late today using the RCS thrusters. The 177.5-second burn provided Cassini a velocity change of 185 millimeters per second.
Sunday, March 17 (DOY 076)
The CDA reprised its retrograde dust observations from Saturday.
Every day this week, the spacecraft turned its high-gain antenna to Earth and downlinked telemetry data to the Deep Space Network (DSN) for six to nine hours, while receiving commands and navigation signals for radiometric tracking.
Monday, March 18 (DOY 077)
CIRS observed the rings while the orbiting particles were in Saturn's shadow, in order to study ring thermal inertia. ISS created a five-hour movie of the rings to search for periodicities in the spokes (http://go.usa.gov/4WGP). ISS then began a six-hour, low-resolution movie of the narrow, complex F ring.
An image featured today captures Mimas in the distance beyond Saturn. This small icy moon's gravitation is responsible for largely clearing out the Cassini Division between the A ring and the B ring, as well as causing some other ring features. It may be viewed here:
Tuesday, March 19 (DOY 078)
ISS reacquired and tracked the orbits of individual known propellers (http://go.usa.gov/YyGR) for an hour. ISS, CIRS and VIMS then took a Titan Meteorological Campaign observation at high phase-angle illumination from 1.9 million kilometers away to monitor long-term cloud activity. UVIS with VIMS, ISS and CIRS as riders observed Saturn's south pole for just over eleven hours, about one planetary rotation, to acquire high spatial resolution data of the aurora and help identify any changes over a planetary rotation time-scale.
This week, the flight team sent instrument-expanded block commands to the spacecraft for use during execution of the next command sequence, S78, which will begin March 26. Later, thanks to the DSN, all 15,850 individual commands were verified as having been properly received across the 1.53 billion kilometers of interplanetary space.