From: Jet Propulsion Laboratory
Posted: Friday, February 25, 2011
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 within a few days.
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