6 Apr 2001
(Source: Jet Propulsion Laboratory)
Cassini Weekly Significant Events for 03/29/01 - 04/04/01
The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Tuesday, April 3. 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 Command & Data Subsystem (CDS) automatic repair of both Solid State Recorders (SSRs), a Reaction Wheel Assembly (RWA) unload, and a High Water-Mark clear. Instrument activities included Spica observations and an Imaging Science Subsystem (ISS) dustband observation with Composite Infrared Spectrometer (CIRS) monitoring, successful normalization of instrument flight software, an ISS Instrument Expanded Block (IEB) load and dark frames activity, restart of the Cassini Plasma Spectrometer (CAPS) actuator sweep, a Radio and Plasma Wave Science (RPWS) HFR calibration, and start of the RPWS Periodic Instrument Maintenance. Commands were sent to increase the Cosmic Dust Analyzer (CDA) multiplier voltage to 3100 volts to better observe the effects on output science data. This was followed by a CDA CPU reset, release and instrument power off. Later in the week CDA was temporarily powered on and a diagnostics mini-sequence successfully run.
The Cassini RADAR was powered on for 23.5 hours of data collection, the most aggressive set of radiometric observations to date. Flight software (FSW) was loaded to the RADAR system from the SSR, data were then collected during raster scans of five microwave sources that are scattered widely over the celestial sphere, as well as Jupiter and the Sun. Jupiter and the sources were observed using two orthogonal polarizations, accomplished by rolling the spacecraft 90 degrees, with 2 raster scans per polarization. Total data volume was roughly 500 Mbits. Included as part of this test was execution of a simulated Titan flyby by using all RADAR instrument modes.
The Radio Science Subsystem (RSS) team performed another series of tests and a boresight calibration to further prepare for the Gravity Wave Experiment (GWE) test to be performed in May. This week's test objective was to characterize the Ka-band Translator behavior. The next opportunity for testing will be next week when an Operational Interface Test/Mission Verification Test (OIT/MVT) will be performed over a three day period.
A Simulation Coordination meeting and a Preliminary Sequence Change Request Approval meeting were held in support of the Cruise 26 development process. A Project briefing for the Cruise 27 sequence was held this week where an integrated plan was presented and approved. Detailed implementation of the plan will now begin.
Several science working groups met this week. The Atmosphere Working Group (AWG) continued development of an overall discipline strategy for the Tour, the Rings Working Group (RWG) worked to identify the key Tour segments and priorities in support of the Cross-Discipline Workshop coming later this month, and the Surfaces Working Group (SWG) began identification and prioritization of the non-targeted satellite opportunities throughout the Saturn Tour.
Two DCMs were held this week. One was for CIMS version 1.1, which provides streamlined access through the Cassini consolidated web server, enhanced security, additional output capability for teams' APGEN requests, and provides the science planning team with enhanced capability to manage the data for sequences under development. The other DCM was held for MSS Version D7.5 software. This version provides an update to SEG in support of the GWE and has now been installed on all appropriate workstations.
The Spacecraft Office has reviewed, approved and released for distribution Revision D of 699-CAS-3-271 The Cassini Functional Requirement Book - Spacecraft Intercommunications.
Navigation Ancillary Information Facility (NAIF) personnel have published an article on the recent NAIF-sponsored Spacecraft, Planet, Instruments, C-matrix, and Events kernels (SPICE) conference. Cassini Team members both attended and presented at this event. The article entitled "SPICE Workshop Brings Enthusiastic Users and Developers Together," is due out in the April 2001 edition of the Science Information Systems Newsletter (SISN), and will be available at:
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