30 Mar 2001
(Source: Jet Propulsion Laboratory)
Cassini Weekly Significant Events for 03/22/00 - 03/28/01
The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, March 28. 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/").
The seventh in-flight Huygens Probe check-out (F7) successfully executed this week. Cassini was at a distance of 880 million km with a one-way-light-time delay of ~49 minutes. The checkout activities were supported by the Huygens Flight Control Team at the European Space Agency Space Operations Center (ESOC). A preliminary analysis of the received data indicates that the Probe and on-board instruments performed well during F7 and that the Huygens system is in good health. The Ultraviolet Imaging Spectrometer (UVIS), Cassini Plasma Spectrometer (CAPS), Magnetospheric Imaging Instrument (MIMI), Cosmic Dust Analyzer (CDA), Radio and Plasma Wave Science (RPWS), Magnetometer Subsystem (MAG), Imaging Science Subsystem (ISS), and the Visual and Infrared Mapping Spectrometer (VIMS) instruments were powered off for the Probe Checkout. All returned to their normal operating states within 24 hours of the completion of the checkout.
Instrument observations this week targeted Alpha Bootes, the Pleiades and Fomalhaut. VIMS sequence C25 activities included the stellar observations in support of better characterizing optical systems, refining the Narrow Angle Camera boresight to VIMS boresight alignment, and assessing optical contamination during the Jupiter flyby period. Data from Alpha Bootes during the "slit-dither" observation is currently being processed. Observations were also made of the Pleiades star cluster and the star Fomalhaut. All three activities were done under reaction wheel control in order to accurately position a star within the field of view. Instrument Operations (IO) and the Multi Mission Image Processing Laboratory (MIPL) have delivered 464 ISS and 470 VIMS products from the observation of Alpha Bootes.
Commanding this week included update of the Command Loss Timer to 11 days one second, part 1 of a CDA voltage adjustment to improve science return, setting of the RPWS write protect bit, writing of the CCSDS header in the housekeeping channel for CAPS, a high watermark clear, and uplink of the Reaction Wheel Assembly (RWA) bias overlay.
IO and MIPL have processed all of the ISS Jupiter downlinks. Although data gaps are still being pursued, the encounter produced 26,287 ISS images (19,061 NAC and 7,226 WAC).
The new Cassini Media Calibration System at Deep Space Station-25 was used in support of a live Cassini track for the first time. Training is in process.
The Radio Science Subsystem (RSS) Team scheduled three days of testing in preparation for the Gravitational Wave Experiment (GWE) System Test to be performed at the beginning of May. On Friday (3/23), a test was performed to characterize the best lock frequency of the Ka-band Translator (KaT). The free running oscillator signal was seen but lock on the KaT was not achieved. The original plan of acquiring data in the 3-link configuration on Wednesday was altered so that lock could be attempted again. The alternate plan utilized a series of discrete tones sent to the spacecraft and a set of 5 sweeps over various regions of the spectrum. KaT lock was still not achieved. Additional scenarios will be developed over the next week and testing will resume shortly.
A Telemetry, Command & Data Management (TC&DM) Deep Space Mission Services (DSMS) delivery review was held for version 26.1. This is a delta from the V26.0 delivery and is primarily focused on capabilities in support of the upcoming Cassini Radio Science GWE system tests. This includes processing the new RSR data types, a new multi-mission Telemetry Delivery and Storage (TDS) to store and retrieve radio science data, a new data interface for radio science monopulse data, and a new Tracking Data Delivery Subsystem for processing the Ka- band uplink exciter tracking data.
Several science working groups met this week. The Atmosphere Working Group continued work on development of an overall discipline strategy for the Tour. The Rings Working Group (RWG) focused on prioritization of all team observations. Substantial progress was made. The RWG is planning 2 telecons per week over the next couple of weeks to get their plans in order in support of the Cross-Discipline Workshop to be held April 17-21.
Mission Planning presented a review of the Mission Plan Guidelines & Constraints on solid state recorder usage at mission planning and science forums this week.
Mission Assurance released the Cassini Risk Management Plan. The plan documents the process Cassini will use to identify, assess, track and manage risks to mission success during the Mission. The initial Significant Risk List (SRL) is currently under development and will be released shortly. The SRL is the basis for initiating the Risk Management process for Cassini.
Outreach personnel presented a workshop, "From High Tech to Low Tech and Back Again" at the TechEd'01 conference on technology in education in Ontario, CA and participated in the NASA exhibit at the National Science Teachers Association meeting in St. Louis.
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