13 Apr 2001
(Source: Jet Propulsion Laboratory)
Cassini Weekly Significant Events for 04/05/01 - 04/11/01
The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, April 11. The Cassini spacecraft is in an excellent state of health and is operating normally. The speed of the spacecraft can be viewed on the "Present Position" web page (http://www.jpl.nasa.gov/cassini/english/where/).
Recent spacecraft activities included a Reaction Wheel Assembly (RWA) unload and a High Water Mark clear. The Imaging Science Subsystem (ISS) observations continued this week. Additional Instrument activities included a Magnetospheric Imaging Instrument (MIMI) Ion and Neutral Camera (INCA) Positive Collimator high voltage test, Flight Software (FSW) checkout for the Composite Infrared Spectrometer (CIRS), conclusion of the Radio and Plasma Wave Science (RPWS) Periodic Instrument Maintenance, and an RPWS HFR calibration. The Cosmic Dust Analyzer (CDA) performed a checkout of their existing Version 7.2 FSW then powered off. Later in the week Version 8 FSW was uplinked with checkout to be scheduled for a later date.
The Radio Science Subsystem (RSS) Operations Interface Test/Mission Verification Test (OIT/MVT) was performed this week in preparation for the Gravitational Wave Experiment (GWE). A comprehensive series of tests spanning three days was executed. The main objectives were three-fold:
- Consistently lock the KaT to the Ka-band uplink.
- Stay locked to the Ka-band uplink.
- Characterize the phase stability of the locked KaT.
The first day of testing saw the KaT locking on several occasions. In a unique event, with the regular X-band uplink also operating, Cassini became the first spacecraft ever to handle dual uplinks from a single DSN station. RSS personnel also observed the longest stable uplink to the KaT since the original checkout over a year ago. The nominal plan for day two of the test included sending real-time commands to cycle the power to the KaT for each uplink attempt. The "normal" wait time between power OFF/power ON cycles has been 30 minutes. One opportunity was used to cut that time to 5 minutes. The result was that the KaT reset itself and came up in the expected frequency region. On the final day of testing, eleven different Ka-band uplinks were transmitted, with the KaT power cycled between each uplink. The KaT was seen to lock ten out of eleven times. With the test now concluded, the compiled data will be analyzed by the RSS team and the Italian Space Agency (ASI). Further testing is scheduled for next week.
RADAR's results from the January measurements of Jupiter's synchrotron radiation were recently presented at two conferences in Europe, the European Geophysical Society meeting and the International Workshop on Planetary Radio Emissions V. These data were the first ever obtained of the Jupiter synchrotron emission in the 2 cm wavelength range. This wavelength is unattainable from Earth-based telescopes. Cassini's radiometer data, which were able to tie down the previously unexplored upper limit, are being combined with new data acquired simultaneously in the 20 cm and 90-cm wavelength ranges by ground-based partners in this experiment (the DSN, the Very Large Array, and the Goldstone-Apple Valley Radio Telescopes). These combined data sets are being used to create new maps of the Jovian energetic particle distribution within Jupiter's radiation belts.
Instrument Operations and the Multi Mission Image Processing Laboratory processed and delivered 702 Imaging Science Subsystem (ISS) Wide-Angle Camera (WAC) asteroid dustband images this week.
The Spacecraft Operations Office (SCO), Cassini Program Manager and Project Scientist supported the fourth Huygens Recovery Task Force (HRTF) meeting held at the Alcatel facility in Cannes, France. This was the first joint meeting with the Huygens Science Working Team participating. The purpose of the meeting was to review the HRTF work done so far and to select the recovery scenarios that will be subjected to a detailed study in the next months. The HRTF has established a very good understanding of the receiver performance as a function of the three main parameters: Signal-to-noise ratio, received frequency, and data bit transition probability. Additional technical work that must be done has been identified to allow a complete evaluation of the respective values of the recovery scenarios.
A team of FSW and spacecraft experts from SCO reviewed the Saturn Orbit Insertion (SOI) system mode test plan. This is a series of Integrated Test Lab (ITL) system mode tests that will examine the interaction of flight software fault protection with the critical SOI sequence. The plan calls for weekly tests through next fall. The team suggested a re-ordering of the test cases and made a few refinements to the tests.
A peer review of the Solid State Recorder (SSR) Management Tool requirements was held, which looked into possible scenarios for data return.
Science instrument teams submitted their files for the first input port for the development of the C27 sequence.
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