Significant Events 05/30/2012 - 06/05/2012
Title: Significant Events 05/30/2012 -
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 CAPS, which is off, and the Ultrastable Oscillator (see the
>nts/significantevents20120105/">Jan. 5, 2012
Significant Events</a>), the Cassini spacecraft is in an
excellent state of health with all its subsystems operating
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
Wednesday, May 30
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
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:
Friday, June 01 (DOY
The Cassini Plasma Spectrometer Subsystem (CAPS) perfomed a 4 hour
calibration of its ion beam spectrometer and its ion mass
Commands were sent to update Cassini's Inertial Vector Propagator
(IVP) to refine pointing information for an observation of Mimas on
Saturday, June 02
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 03 (DOY
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:
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
Monday, June 04 (DOY
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:
VIMS observed the unlit side of the rings for composition
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,
Tuesday, June 05
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:
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
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