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Cassini Mission Status

2004 January 20

Cassini Significant Events for 01/08/04 - 01/14/04

The most recent spacecraft telemetry was acquired from the Goldstone tracking station on Tuesday, January 13. The Cassini spacecraft is in an excellent state of health and is operating normally. Information on the present position and speed of the Cassini spacecraft may be found on the "Present Position" web page located at .

Cruise sequence C40 concluded this week with uplink of a trigger mini-sequence for the Composite Infrared Spectrometer (CIRS), start of execution of the Cassini Plasma Spectrometer (CAPS) Solar Wind mini-sequence, uplink of instrument expanded blocks (IEB) in support of C42, and uplink of the C42 background sequence.

C42 began execution on Friday, January 9. Initial activities included instrument wake-up and IEB loads, an Ion and Neutral Mass Spectrometer pressure test, uplink of Cosmic Dust Analyzer (CDA) flight software version 9.2, CAPS and Radio and Plasma Wave Science solar wind observations, CDA articulations, and a reaction wheel unload.

With the start of C42, the Cassini orbiter has begun its Approach Science phase. The previous "cruise" phase included instrument calibrations and infrequent science opportunities. Approach Science consists of a set of continuous science observations between now and Saturn Orbit Insertion in July 2004. The level of science activity is representative of the upcoming Tour phase, and the flight team will be using tour processes and operational modes as expected in tour operations.

One of the features of the Approach Science phase is a month-long campaign to monitor the solar wind impinging on Saturn's magnetosphere using CAPS, the Magnetometer Subsystem (MAG), and the Magnetospheric Imaging Instrument (MIMI) while monitoring Saturn's auroral radio emissions with RPWS. MIMI and RPWS will look for upstream waves and particles, or disturbances in the solar wind caused by its interaction with Saturn's magnetosphere. The Hubble Space Telescope will also be carrying out a campaign at this time to monitor Saturn's ultra violet emissions periodically. The goal of these observations is to understand how Saturn's magnetosphere responds to changes in the solar wind. For the remainder of the Approach Science phase, the Magnetospheric and Plasma Science (MAPS) instruments will continue to monitor the solar wind but from a less-advantageous orientation while continuing to monitor Saturn's radio emissions and search for upstream waves and particles. Throughout, CDA will look for Saturn dust streams similar to those emanating from Jupiter.

Remote sensing observations during the Approach Science phase include Saturn ring and atmospheric movies by the Imaging Science Subsystem (ISS) and the Visual and Infrared Mapping Spectrometer (VIMS), searches for new satellites and their orbit determinations by ISS, extended Ultraviolet Imaging Spectrograph (UVIS) system scans to search for hydrogen emissions, CIRS ring and Saturn atmospheric composition measurements, and optical navigation images to refine the ephemeredes of the known satellites. During the last month of this phase, monitoring by ISS of Titan's surface and clouds will begin, along with diffuse ring observations to search for unidentified ring hazards close to the planet.

This month we are executing the month-long MAPS campaign. Next month we start Optical Remote Sensing observations, and more MAPS.

As part of the C43 development process, uplink operations personnel (ULO) began the processing of IEB loads. No waiver disposition or Science Allocation Panel meeting was held during the C43 Preliminary Sequence Integration and Validation 1 phase process as no additional waivers were submitted, and the DSN allocation file did not require any changes to the SSR management strategy. ULO is working with the Spacecraft Operations Office to build and test command files for the Probe Relay demonstration to be executed in C43. Over 40 real time command files are required for this activity.

A waiver disposition meeting and a final wrap up meeting were held as part of the Science Operations Plan (SOP) implementation process for tour sequences S19/S20. The S19/S20 products are now archived, and will be reactivated for execution in March, April, and May of 2006.

Official port #1 occurred for SOP implementation of S21/S22. The merged Spacecraft Activity Sequence File (SASF) is now being run through Inertial Vector Propagator (IVP)/ Kinematic Prediction Tool (KPT) to validate the end-to-end pointing profile. The S23/S24 SOP Implementation process kicked off this week and will complete on March 11, 2004.

The next process to follow SOP Implementation in the development of a tour sequence is the Aftermarket process. This 5-week process addresses both mandatory and proposed discretionary changes that would require re-integration of segments contained in a sequence. The proposed changes would include requests by science and engineering that involve modifications to key shared resources including, but not limited to, spacecraft attitude, data volume, observing time, op modes, telemetry modes, and waypoints. After the cutoff for changes has been reached, an assessment meeting chaired by the Project Scientist is held to scope out the proposed changes. Later in the process a final decision meeting is held on what changes will be made to the sequence plan. The appropriate Target Working Team or Orbiter Science Team will then integrate approved changes. If it turns out that no discretionary changes are requested, the Aftermarket process for that sequence is cancelled and the sequence developed as part of the SOP Implementation process moves on to SOP Update.

All approved Aftermarket changes have been accommodated for tour sequence S01 and the process has completed. The S01 SOP Update Process will begin on January 30, 2004. All requested S02 Aftermarket changes were received this week. The S02 Aftermarket Assessment meeting will be held next week to review the scope of the requested changes.

The final port#3 occurred as part of the C44 Science Planning Team process. C44 is the last approach science sequence before the start of tour with S1. The merged SASF for C44 is now being run through IVP/KPT to validate the end-to-end pointing profile. This process will end this week and will be followed immediately with the C44 Science and Sequence Update Process beginning on January 20.

All teams and offices supported this week's Cassini Monthly Management Review.

The Project Scientist released a draft agenda for the Project Science Group meeting to be held at the California Institute of Technology in Pasadena, California the last week of January.

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 Outreach
Cassini Mission to Saturn and Titan
Jet Propulsion Laboratory
California Institute of Technology
National Aeronautics and Space Administration

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Copyright © 2004, Brian Webb. All rights reserved.