Cassini Significant Events 05/30/2012 – 06/05/2012

The most recent spacecraft tracking and telemetry data were collected on June 6 by the Deep Space Network's 70 meter Station 14 at Goldstone, California. Aside from the Cassini Plasma Spectrometer Subsystem (CAPS), which is off, and the Ultrastable Oscillator (see the Jan. 5, 2012 Significant Events), the Cassini spacecraft is in an excellent state of health with all its subsystems operating normally. 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/.

This week's highlight was a Radio Science occultation experiment. On Monday, telemetry was turned off and the spacecraft's radio emissions actively probed Saturn's rings and atmosphere as they passed through the rings and atmosphere en route to Earth while the spacecraft passed behind them as seen from Earth.

Negotiations to schedule Deep Space Network (DSN) antennas to support Cassini's next command sequence, S74, continue to pose a significant challenge.

Wednesday, May 30 (DOY 151)

Orbit Trim Maneuver (OTM) 324, which was covered in last week's report, finished executing early this morning.

The Magnetometer performed an eight-hour calibration while rotating the spacecraft about its X-axis.

Thursday, May 31 (DOY 152)

The 70-meter diameter Deep Space Station 63 participated in an Operations Readiness Test in preparation for Monday's Radio Science occultation experiment. As usual, the station also sent commands, acquired telemetry, and provided Doppler and range data for navigation. This was one of a total of ten DSN tracking activities for Cassini this week.

A feature titled, "Enceladus Plume is a New Kind of Plasma Laboratory" was posted today, describing the "dusty plasma" that issues from the small icy moon:
http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20120531/

Friday, June 1 (DOY 153)

The Cassini Plasma Spectrometer Subsystem (CAPS) perfomed a 4 hour calibration of its ion beam spectrometer and its ion mass spectrometer.

Commands were sent to update Cassini's Inertial Vector Propagator (IVP) to refine pointing information for an observation of Mimas on Tuesday.

Saturday, June 2 (DOY 154)

Yesterday and again today, the Imaging Science Subsystem (ISS), the Composite Infrared Spectrometer (CIRS), and the Visible and Infrared Mapping Spectrometer (VIMS) performed observations in the Titan monitoring campaign, and ISS and VIMS made observations in the Satellite Orbit Campaign.

During the American Cancer Society Relay for Life Walk-a-thon in Monrovia, California, Cassini Outreach offered views of Saturn and Titan to hundreds of participants. Saturn will continue to be a great viewing target in small telescopes though August.

Sunday, June 3 (DOY 155)

Telemetry showed that CAPS was powered off yesterday when the instrument began to draw excess current, which tripped off the solid state power switch (SSPS) that provides electrical power to the instrument. The Realtime Operations Team notified the CAPS instrument team, the Spacecraft Operations team, and the Sequence Implementation Process lead, and an anomaly meeting was arranged for the following morning. More information may be found in this news release:
http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20120606/.

The Ultraviolet Imaging Spectrograph (UVIS) carried out a 13 hour observation of Saturn's aurora.

OTM-325, the Titan 84 approach maneuver, executed today using the Reaction Control Subsystem thrusters. The burn provided a delta-V of about 37 millimeters per second.

Monday, June 4 (DOY 156)

An anomaly meeting was held to deliberate on yesterday's CAPS shutoff. It was decided to conduct further analysis and not turn the instrument back on until such time as the anomaly is better understood.

ISS had one of its first looks at the rings in nearly two years, now that Cassini's orbit is inclined somewhat out of the ring plane. Part one of the observations began an azimuthal survey of the region where propeller-shaped objects had been found. More information on these features can be found here: /resources/15045

VIMS observed the unlit side of the rings for composition data.

The Radio Science Subsystem team performed an ingress occultation experiment, probing Saturn's rings, ionosphere, and upper troposphere using Cassini's three radio-frequency bands: S, X, and Ka. Since the Ultrastable Oscillator is inoperative, the DSN provided the reference frequency via uplink; this use of coherent mode is a first for an occultation experiment. The spacecraft's downlink was received and recorded at 70- and 34 meter stations in Madrid, Spain, and Goldstone, California.

Tuesday, June 5 (DOY 157)

Cassini passed through periapsis just outside the orbit of Mimas going 69,739 kilometers per hour relative to Saturn.

UVIS led an egress solar occultation observation as the Sun rose, by virtue of spacecraft motion, through Saturn's upper atmosphere.

Thanks to the IVP update commanded on Friday, CIRS found Mimas well centered in its field of view and made observations of the small moon to better define its thermally anomalous "pacman" feature. The other ORS instruments observed in ride-along mode. The unusual surface feature is illustrated here: /resources/14919

VIMS made a ring composition lit-face study. Finally, ISS performed part two of the propeller survey.

Yesterday and again today, the Attitude and Articulation Control Subsystem team executed reaction-wheel bias maneuvers.

The S74 sequence Instrument Expanded Block commands were processed and approved for uplink starting on Thursday.

A web page detailing the upcoming Titan T84 encounter was posted here:
http://saturn.jpl.nasa.gov/mission/flybys/titan20120607/