27 Apr 2001
(Source: Jet Propulsion Laboratory)
Cassini Weekly Significant Events for 04/19/01 - 04/25/01
The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Tuesday, April 24. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the spacecraft's position and speed can be viewed on the "Present Position" web page at ("http://www.jpl.nasa.gov/cassini/english/where/").
Recent spacecraft activities include automatic repair of the Solid State Recorder (SSR) A, a Radio and Plasma Wave Science (RPWS) High Frequency Receiver (HFR) calibration, a Reaction Wheel Assembly (RWA) momentum unload, and uplink and successful checkout of a new 35.5kbps telemetry mode. Previously, the highest useable telemetry rate was 22kbps. By using the new 35.5kbps capability, Cassini can raise the downlink telemetry rate by more than 50%.
Additional instrument activities include power-on of the Composite Infrared Spectrometer (CIRS) followed by a boresight calibration, and upload of a mini-sequence for the Cosmic Dust Analyzer (CDA). CDA powered on, performed a checkout of its version 8.4 Flight Software, then switched on the high voltages to reach a basic measurement mode. All activities executed normally, and CDA is in a healthy and nominal state.
The Radio Science Subsystem (RSS) team obtained 4.25 hours of Ka-Band Translator (KaT) 2-way data as part of continued testing of the KaT module, one of four radios onboard the spacecraft. This is the longest period of continuous KaT operation since early 1999, and is significant in the on-going efforts to characterize the performance of the KaT in support of the Gravitational Wave Experiment (GWE) system test, scheduled to begin in early May.
The final Sequence Integration & Validation (SIV) approval meeting was held for the Cruise 26 sequence. Uplink will occur later this week.
A week long Cross-Discipline Workshop sponsored by Cassini Science Planning concluded this week. The goals of this workshop included the identification of heavily conflicted periods, the division of the tour into segments and the creation of Target Working Teams. Major progress was made by all teams in all areas and the workshop was felt to be a great success. Science Planning also hosted a Titan Orbiter Science Team (TOST) meeting this week.
The Navigation Team has completed a study on the feasibility of raising the minimum Titan flyby altitude to as high as 1050 km as a contingency in case the actual Titan atmosphere precludes flying at the current minimum of 950 km. The results of the study indicate that all Titan flybys and all icy satellite flybys remain in the tour. The geometries of the Titan flybys change only slightly. There is actually a small savings in deterministic propellant cost.
Mission Support & Services Office (MSSO) personnel presented the Cassini security and International Trade in Arms Regulation (ITAR) environment to members of the JPL Executive Council. The Council was favorably impressed and indicated that Cassini had taken a lead in handling NASA and Government mandated security and ITAR issues in the JPL community. MSSO also prepared flow diagrams outlining the process used to allow foreign nationals access to JPL. These diagrams will be used to interface with JPL International Affairs and other organizations associated with the process, assist in developing and streamlining current MSSO procedures, and may also help users in understanding the big picture of the ITAR process.
The Command and Data System (CDS) Flight Software team held a delivery review for version RV70_11.3. This upgrade contains a patch to the fault protection response for a tripped solid state power switch on the magnetometer replacement heater. All requirements for functionality, testing, and documentation were met and the patches were delivered to the Project Software Library. Uplink of the new software will occur in May during the C26 sequence.
A Delivery Coordination Meeting (DCM) was held for the Cassini implementation of Multimission Spacecraft Analysis Software (CSAS) 6.3. Although most of the subsystem remains unchanged, both the Inertial Vector Propagator (IVP) and Predicts Generation Tool (PGT) had batch modes added, while the Kinematic Prediction Tool (KPT) had batch mode added, constraint monitor detect mode turned on and RWA output logic improved.
Mission Assurance released the draft Significant Risk List (SRL) for flight team review. This list represents an initial cut at the high level Program risks that will be managed using the Risk Management Process. Once this list is reviewed and refined, it will be input into an electronic Risk Management Tool.
Instrument Operations (IO) hosted a member of the CDA Team from the Max Planck Institut fur Kernphysik, Heidelberg, Germany, for a week of operations training sessions following last week's cross discipline workshop. Representatives from Cassini's Uplink Office, IO, System Engineering, and MSSO contributed with a variety of training. In an effort to increase effectiveness, many of the sessions were made available to program members who had previously expressed an interest in additional training.
In cooperation with the Cassini Program, and drawing from material developed for the Cassini Web site, a planetarium program has been developed for school children and debuted at the Howell Memorial Planetarium in Greenville, South Carolina. Three different schools attended the program with 125 students and 15 teachers in attendance.
On Friday, 4/20/2001, Cassini was featured on the "Astronomy Picture of the Day" web site, http://antwrp.gsfc.nasa.gov/apod/ap010420.html.
Two new Cassini 20-slide sets were submitted to Finley-Holiday Film Corporation for production. Set #1, "A Trip to Saturn" highlights the launch, trajectory, tour, and planetary flybys. Set #2, "Saturn System" highlights the planet, satellites, rings, magnetosphere, and Titan. When available, both sets may be obtained through Finley.
Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, Calif., manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.
Cassini Mission to Saturn and Titan
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration