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Cassini Significant Events 02/16/11 - 02/22/11 The most recent spacecraft telemetry was acquired on Feb. 22
from the Deep Space Network tracking complex at Madrid, Spain. The Cassini
spacecraft is in an excellent state of health and all subsystems are 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/.
Thursday, Feb. 17 (DOY 048) The Reaction Wheel Assembly (RWA)-4 to 3 and RWA-3 to 4
swaps were tested in the Integrated Test Laboratory (ITL) today. These tests
support the use of RWA-3, which is currently the backup wheel aligned with RWA-4.
This alignment makes RWA-3 and RWA-4 interchangeable without any articulation
of RWA-4. Friday, Feb. 18 (DOY 049) Cassini encountered Titan (T-74) today at an altitude of
3,651 kilometers and a speed of 5.8 km/sec. Closest approach occurred at 16:04:11SCET
at a latitude of 0.7 degrees N. This was a post-dusk, upstream, high altitude
flyby that will be useful to characterize the background magnetic field in
which Titan sits. The Cassini plasma spectrometer (CAPS) continued its
observations of Titan's plasma interaction as the moon moves from south to
north of Saturn's solar-wind-warped magnetodisk from one solstice to the next. T-74 was the sixth Titan flyby of the Cassini mission to
provide an opportunity for RSS to acquire gravity data. As with previous
gravity science flybys at Titan, the goals of this gravity experiment were to
measure the dynamic Love number of Titan and determine Titan's geoid. The
determination of the Love number is the only way to find out with confidence
whether Titan has an internal liquid ocean. The determination of the geoid is
crucial to understanding the internal structure of Titan through correlative
analysis of the gravity data and RADAR radius data. The observation was covered
by beam wave guide (BWG) antennas at all three complexes starting with Madrid's
DSS-55, followed by Goldstone's DSS-25, then Canberra's DSS-34, and ending with
DSS-55 agan. Special unramped uplink predicts were used to improve the data
quality. It was a successful observation with 23 hours of continuous coherent
data acquired, centered around Titan closest approach. Port 3 products were due today as part of the S68 Sequence
Implementation Process (SIP). The products will be merged and sent out to the
flight team for review. Saturday, Feb. 19 (DOY 050) Orbit Trim Maneuver #278, the T-74 cleanup maneuver
scheduled for Feb. 21, was cancelled today. Confidence in the preliminary orbit
solution accuracy and resulting maneuver analysis enabled an early decision
regarding OTM-278. The resultant pointing errors are negligible and no live
update will be necessary. Sunday, Feb. 20 (DOY 051) Non-targeted flybys of Enceladus, Pallene, and Tethys
occurred today. Monday, Feb. 21 (DOY 052) This week's science kicked off with the T-74 flyby on the
inbound portion of the trajectory. The Saturn periapsis period following the
T-74 flyby focused on magnetospheric observations. CAPS made measurements of
the Saturnian plasma environment, concentrating on the equatorial inner
magnetosphere. Two Cosmic Dust Analyzer (CDA) measurements were made during
ring plane crossings to measure dust densities and size distributions. The
Ultraviolet Imaging Spectrograph (UVIS) then performed slow scans across Saturn
to form spectral images and probe the upper atmospheric composition. Outbound
from Saturn, Imaging Science and UVIS observed the small outer irregular moon
Siarnaq, followed by an additional UVIS spectral map of Saturn. Tuesday, Feb. 22 (DOY 053) The most recent Cassini-Huygens Analysis and Results of the
Mission (CHARM) teleconference was held today. The topic: "Trajectory
Design in the Saturnian System". A PDF of the presentation package may be
obtained at:
http://saturn.jpl.nasa.gov/video/products/MultimediaProductsCharm/. An audio
recording of the presentation was made and will be linked to the same location
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