Cassini Significant Eventsfor 05/18/06 - 05/24/06
The most recent spacecraft telemetry was acquired Wednesday, May 24, from the Goldstone tracking stations. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the"Present Position" web page located at http://saturn.jpl.nasa.gov/operations/present-position.cfm .
Friday, May 19 (DOY 139):
Per commands in the background sequence, the Main Engine (ME) cover as closed today as a preventive measure for dust avoidance near Dione’s orbit. It will be reopened on Monday. The last time the cover was moved was about seven months ago. It was closed on October 9, 2005, for a ring plane crossing, and then reopened on October 12. It will not be moved again till late June of 2006.
Saturday, May 20 (DOY 140):
The big news today is the Titan 14 (T14) flyby. Cassini passed by thesatellite at an altitude of 1879 kilometers. During this flyby, the Radio Science Subsystem (RSS) took advantage of an ingress/egress occultation of Earth by Titan to provide a high-spatial-resolution electron number density profile of Titan’s ionosphere, temperature, pressure, and absorption profiles of the neutral atmosphere, as well as information about the small-scale structure of the atmosphere such as gravity waves, turbulence, etc.
The Madrid DSN complex covered both the ingress and egress bservations. The 70-m DSS-63 covered S- and X-bands. The 34-m DSS-55 covered Ka-band and provided backup X-band. RCP and LCP polarizations were recorded at the Earth receiving stations.
A “quick-look” analysis of the signal intensity profiles computed fromthe 1 KHz bandwidth recorded data indicate high quality S-, X-, and Ka-band ionospheric and atmospheric occultation data were acquired on both the ingress and egress sides. Signal frequency data was also collected and appears to be of equally good quality.
After a “quick-look” analysis of the recorded 16 KHz bandwidth T14 dataanalyzed last night, the RSS Team is happy to report the successfuldetection of the first ever bistatic echo received from the surface ofTitan. It is a whisper, as if Titan is trying to hold back on one moreof its secrets, but is no doubt real, and is beautiful! The detection is,of course, the first step towards the goal of finding out what the echotells us about the surface region probed.
The similarities between the occultation observations at T12 and T14indicate very little pointing errors, although a quantitativeassessment is yet to be completed. The limb-track maneuver appears to have executed as planned. T12 and T14 are the only two RSS Titan occultations during 2006.Titan 27 and 31 will follow in March and May of 2007. The excellentdata from T12 and T14 will keep the RSS team busy until T27!
The Composite Infrared Spectrometer (CIRS) performed high spectralresolution studies of Titan’s limb in the far-infrared regime to searchfor new species and to map the vertical distribution of CO, CH4, HCN andH20. CIRS also continued existing campaigns of global temperaturecomposition mapping, extending spatial and temporal coverage.
The Ultraviolet Imaging Spectrograph (UVIS) probed haze opticalproperties, atmospheric nitrogen emissions and hydrocarbon absorption, and absorption by methane of the Lyman-alpha interplanetary background, which will ultimatelyhelp us understand the distribution of methane in the thermosphere ofTitan. The Cosmic Dust Analyzer (CDA) performed two eccentricity scans. These observations allow separation of orbital elements to the greatestdegree possible by having the spacecraft rolling with a rotation axis which is parallel to the ring plane so that dust particle inclinations can bedetermined.
Sunday, May 21 (DOY 141):
On Sunday and Monday, UVIS performed some Saturn occultationobservations using the stars Beta Orionis, Epsilon Orionis, and Zeta Orionis. These observations will yield the temperature of Saturn’s high atmosphere and vertical profiles of H, H2, and hydrocarbons. The Visual and Infrared Mapping Spectrometer (VIMS) performed a couple of Saturn thermal cylindrical mappings as well.
At the end of the day today, there were some exhausted but very happyCassini folks here at the lab. This weekend, JPL held its annual OpenHouse. Approximately 30,000 people visited the lab during the 2-dayevent. Cassini had a large exhibit on the JPL mall. The exhibit featuredimages from the Saturn tour, a display of Synthetic Aperture RADAR images, two plasma screen monitors showing Cassini video clips, a full-scale model of the Huygens Probe, and a half-scale model of the Cassini orbiter - including half scale people! The DVD “Ring World” was showing in a nearby conference room. Cassini image data and “sounds” were also featured in the DSN and ‘Sounds of the Solar System’ booths. A Girl Scout troupe used the “Moon Walk, Saturn Style” on their scavenger hunt to answer questions, work on badges and walk Saturn’s moons from Pan to Phoebe. Feedback from the public was extremely positive. Nearly 40 members of the flight team spent all or part of their weekend visiting with guests at our locations.
Monday, May 22 (DOY 142):
A non-targeted flyby of the Saturnian satellite Polydeuces occurredtoday at an altitude of 64057 kilometers.
The ME cover opened today per plan after the T14 flyby, and afterCassini had cleared any possible dust hazards.
Tuesday, May 23 (DOY 143):
A delivery coordination meeting was held today for Inertial VectorPropagator (IVP) version 12.0, and Kinematic Prediction Tool (KPT)version 12.0. The software was approved and installation plans and instructions were reviewed.
The Spacecraft Team uplinked an RWA bias today in place of Orbit TrimManeuver #62.
Wednesday, May 24 (DOY 144):
The sequence leads for S21 requested a loading test for the transitionfrom S20 part 2 to the S21 background sequence. That test completedsuccessfully today in the Integrated Test Laboratory. There should be no problems with the start of execution of S21.
It has been determined that the magnitude of Orbit Trim Maneuver (OTM)#62 would only be 0.8 mm/sec, and as a result, OTM 62 has been cancelled.
A delivery coordination meeting was held today for the tool ElectronicCommand Request Form version 1.5. The software was approved andinstallation plans and instructions were reviewed.
Wrap up:
Check out the Cassini web site at http://saturn.jpl.nasa.gov for thelatest press releases and images.
The Cassini-Huygens mission is a cooperative project of NASA, theEuropean Space Agency and the Italian Space Agency. The Jet PropulsionLaboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter.