From: Jet Propulsion Laboratory
Posted: Friday, February 1, 2002
The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Wednesday, January 30. 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.
The C30 sequence continues to execute as planned. Science activities this week include acquisition of the second set of images in support of the Imaging Science Subsystem (ISS) decontamination mini-sequence, and uplink and execution of a modification to the VIMS Image/Occultation mini-sequence. Twenty decontamination images were obtained as part of last week's ISS observations. Although the images obtained provided the desired information, the star Spica was found to be off center of frame by about 30%. The ISS team will correct this for future decontamination activities.
Spacecraft activities included clearing of the AACS High Water Marks and a system command to reset the SSPS trip counter.
In support of a Deep Space Network (DSN) request to test a new version of their firmware, an Immediate/Delayed Action Program (IDAP) was executed, putting Cassini into 82K downlink mode over DSS-15, and returning to S&ER3 near the end of the pass. Mission Support and Services Office personnel reported that despite early indications that the test was successful, not all test objectives were met. After further analysis, DSN personnel have determined that additional test support will be requested.
The Sequence Change Request approval meeting for C31 was held this week. The Spacecraft Activity Sequence Files (SASF) were integrated and the preliminary Sequence Integration & Validation (SIV) files were released. It has been determined that sequence simulation will not be required for the C31 background sequence. As a result, the simulation requirements meeting and simulation procedure review meeting have been cancelled.
Science Planning (SP) chaired a Project briefing for C32 to approve the integrated product for implementation. The Program Manager approved the current contents of the plan. Other activities included a half-day SOST meeting to continue work on the SOST-assigned tour segments in orbits 11 and 12, and Target Working Team meetings to work towards the next integration milestone. This milestone includes orbits 10 through 15.
Members of the JPL Planetary Data System Imaging node met with members of the Imaging Science Subsystem team at the Southwest Research Institute (SWRI) in Boulder, CO to discuss archiving. The meeting was very successful in that Imaging node software was identified that may be transported to SWRI. This software will automate a considerable portion of the image archiving process. Groundwork has now been laid to establish a pipeline that can be tested, and archiving of the Jupiter flyby data should be completed before the scheduled deadline.
A Ground Data System 10 bps telemetry rate DTF-21 dataflow test was performed this week. The test is in support of a CDS flight software patch to be uplinked in early February. Preliminary test reports indicate nominal results; however, additional analysis is still pending.
MSSO chaired an ITAR, MSSO, and Program discussion. A few of the issues covered were access to JPL networks, remote access by foreign nationals, and ITAR log keeping requirements. This meeting will be held quarterly to assess the current situation.
Mission Assurance attended the JPL Project Risk Management Class and gave a presentation illustrating the Cassini approach to Risk Management during Mission Operations.
Mission Assurance has aggressively worked the closure of Incident Surprise Anomaly (ISA) reports with the Cassini Office Managers. To date, 48 ISAs have been resolved and closed during the month of January. Plans are to work ISAs on a regular, systematic basis, to ensure that issues are given adequate attention in a timely manner and are resolved promptly, where possible.
Mission Planning (MP) received a proposed flight rule from the Composite Infrared Spectrometer (CIRS) instrument team indicating allowable dust damage at Saturn for the CIRS instrument. MP coded the flight rule and began assessing its effects on science sequencing.
Topics at the Mission Planning Forum this week included discussion of the addition of a maneuver window to the baseline after the SOI - 15 day burn, and determination if a credible failure exists which would keep us from executing the T - 3 day trajectory correction maneuver.
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.
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