NASA Cassini Significant Events for 08/11/05 – 08/17/05
The most recent spacecraft telemetry was acquired Wednesday, August 17, from the Goldstone tracking stations. 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 http://saturn.jpl.nasa.gov/operations/present-position.cfm .
Activities this week:
Thursday, August 11 (DOY 223):
Cassini’s orbit passed through apoapsis today and began the 13th orbit of tour. While in the apoapsis region, the Imaging Science Subsystem (ISS) made a movie of Saturn’s southern hemisphere, and the Visible and Infrared Mapping Spectrometer (VIMS) studied the rings in a mosaic.
As part of sequence development for S15, the sequence leads released the preliminary cycle 1 integrated sequence products for review and for ACS Inertial Vector Propagator (IVP) & Kinematic Prediction Tool analysis.
Friday, August 12 (DOY 224):
A CDS flight software (FSW) patch uplink readiness review was held for the SSR auto repair correction. This patch will be uplinked in mid-September.
The last time members of the Spacecraft Operations Office (SCO) looked at a time frame for the first fuel-side bipropellant repressurization planned in the tour, it appeared that it did not need to be performed until around December 2005. This repressurization is a procedure required to keep the main engine operating normally. Several changes have occurred since the last assessment: trajectory changes have increased the biprop delta-V used during the last year, as has the decision to lower the delta-V threshold for RCS thruster vs. main engine use. It is now evident that the activity should occur before OTM-33. Currently it is planned for mid-September, right before the CDS FSW patch upload.
Mission Planning has been working on a maneuver cancellation process and presented the latest version to the Live IVP Update Working Group. This group has the basic science representation from Radio Science, RADAR, and the Optical Remote Sensing instruments that deal with trajectories, orbit determination deliveries, uncertainties, etc.
Sunday, August 14 (DOY 226):
This was the chance to hear Michael Oare’s composition “Cassini’s Rings” performed live in its west coast premier. A member of the Cassini flight team arranged with the composer, and with the conductor of the La Cañada Community Band, to present this piece on Sunday, August 14th, at Memorial Park in La Cañada, California. The Grafton Middle School in Yorktown, VA, originally premiered the piece at a spring concert in June of this year.
SCO reported that a calibration was performed on Inertial Reference Unit-A over Sunday and Monday. Performance of the unit continues to be excellent.
Monday, August 15 (DOY 227):
VIMS performed an Automated Sequence Processor (ASP) command to update the command load in the instrument. This update corrects one trigger, which the science team incorrectly planned and noticed too late to correct in the S13 uplink process. The update was successfully performed.
Members of the ACS and Integrated Test Laboratory teams supported and presented at the AIAA Guidance, Navigation, and Control conference in San Francisco, California the week of August 15.
A calibration of the Radio Science Subsystem (RSS) HGA boresight was performed today.
Instrument Operations and the Multi-Mission Image Processing Laboratory participated in extensive testing of an engineering version of FEI-5. This File Exchange Interface system is used by the MER and MRO flight projects. Their use of this system has significantly impacted Cassini and Spitzer throughput of instrument science products. Due to the architecture of a multi-mission facility, missions share resources even if they are running independent applications. For instance, the applications can be running on the same CPU, accessing the same database server and/or getting authentication from the same password server. Resources such as these may be temporarily held by one project doing its independent work. The other projects may be locked out or access restricted until the resources again become available. Testing this week involved baseline tests, problem reproducibility and problem resolution tests. The engineering version caused no adverse effects and significantly reduced the impact on Cassini.
Tuesday, August 16 (DOY 228):
A meeting was held today to determine if Orbit Trim Maneuver (OTM)-28, scheduled for Thursday of this week should be cancelled. The small magnitude of the maneuver, 50 mm/sec, taken together with a resulting cost downstream of less than 1 m/sec, indicated that the maneuver was not required. This along with the necessity of the team working overnight to perform the maneuver convinced management to cancel it.
All signatories have approved the Cassini Plasma Spectrometer Archive Software Interface Specification (SIS) document. Only one archive SIS remains to be completed.
Near the end of this week, Cassini came within 608,000 km of Hyperion. ISS studied the satellite’s geology while Ultraviolet Imaging Spectrograph measured its ultraviolet albedo. The Composite and Infrared Spectrometer (CIRS) made high spectral resolution infrared measurements for composition analysis. These results laid the groundwork for a 1010 km targeted flyby in S15.
Wednesday, August 17 (DOY 229)
The full merged preliminary cycle 2 products for S14 were released today. This includes files for the background sequence and the live moveable block. The associated Space Flight Operations Schedule will be released tomorrow.
The final science event this week was a CIRS longitudinal scan of the rings to study seasonal effects due to elevation of the sun and screening of the rings.
Wrap up:
Check out the Cassini web site at http://saturn.jpl.nasa.gov for the latest press releases and images.
Additional:
Outreach has released the Cassini Science Highlights for August. A reduced version of this information has been included below.
Cassini Reveals Saturn’s Eerie-Sounding Radio Emissions
http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=589
Cassini’s Latest Findings About Enceladus
http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=590
Evidence of Ice Volcanism on Enceladus
http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=592
Nested Craters on Mimas Tell of a Heavily Tortured Past
http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=593
The Cassini-Huygens mission 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, manages the Cassini-Huygens mission for NASA’s Science Mission Directorate, Washington, D.C. JPL designed, developed and assembled the Cassini orbiter.
