Status Report

NASA Cassini Significant Events for 07/13/06 – 07/19/06

By SpaceRef Editor
July 21, 2006
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NASA Cassini Significant Events for 07/13/06 – 07/19/06

The most recent spacecraft telemetry was acquired Wednesday, July 19, 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 .

Thursday, July 13 (194):

The fifth delivery of Cassini Orbiter science archive data occurred on July 5. Most instrument teams delivered prior to the due date with only a few exceptions. One team ran into some snags delivering some calibration files, but these will be delivered by the end of July. At this date, data for archive deliveries 1 through 4 have been 100% accepted by the Planetary Data System (PDS).

Friday, July 14 (DOY 195):

Science activities for today include an Ultraviolet Imaging Spectrograph (UVIS) calibration measurement. The calibrations will be achieved by characterizing the spectral emissions of a well-known star. This will be followed by an Imaging Science Subsystem (ISS) observation of a satellite transit event – Epimetheus across Janus – concluding with an ISS search for Saturn lightning.

Orbit Trim Maneuver (OTM)-67, the Titan 16 approach maneuver set for July 18, has been cancelled. The current estimate for this maneuver is about 1.4 mm/sec. This change would not be required to control the trajectory of the spacecraft, and is too small to be accomplished. In place of the OTM, an RWA bias will be performed on the 18th. Science Planning has verified that a Live Update will not be required as a result of the cancellation. The flight team wishes to thank Navigation for making this determination so early in the week. It means the rest of the team does not have to work the weekend!

Uplink Operations sent the S22 background sequence to the spacecraft today. At this time, all Instrument Expanded Block (IEB) files and sequence files have been registered on board and are ready to begin execution on Sunday, July 16.

A strategy has been finalized for providing a second playback for most of the Titan 16 closest approach data. Closest approach occurs on Friday, July 21, with an initial playback scheduled to occur on Saturday, July 22, DOY 203. The second playback track will occur on Sunday, DOY 204. An estimated 75% of the closest approach data will be downlinked a second time on that day. This provides some insurance against data loss on DOY 203. The strategy will also minimize the chance of data loss for the post Titan rings observations. If a data loss should occur on DOY 203, without the second track on 204 it would be necessary to stop recording rings data in order to playback the Titan data. The files for the DOY 204 playback are now being built by SCO with input from Science Planning, Mission Planning, project management, and the S22 sequence leads.

A delivery coordination meeting for the SCO tools Telemetry Input Gap Analyzer & Reporter version 2.0, and Assisted Load Format version 11.1 was held today. Both deliveries were approved and have been installed by the Cassini Mission Support and Services Office for operational use.

Sunday, July 16 (DOY 197):

The keys to the spacecraft were handed over to the S22 sequence leads today. S22 began execution at 2006-198T00:06:00 UTC and will run for 34 days from July 16 through August 19. During that time Cassini will have one targeted flyby of Titan, T16, and four non-targeted flybys, one each of Tethys, Telesto, Helene, and Titan. Three OTMs have been planned, numbers 67, 68, and 69. An annual event, Superior Conjunction, will occur during this sequence beginning on August 1 and concluding on August 13 with minimum separation angle achieved on August 7. During that time, a command moratorium will be in place from August 5 through August 9, and the primary science observation will be the Radio Science Solar Corona Characterization.

Monday, July 17 (DOY 198):

Late on July 17 the Visual and Infrared Mapping Spectrometer (VIMS) performed a 10.5-hour mapping of Saturn’s E Ring near 160 degrees phase. This observation mapped both E Ring ansae for vertical and radial structure. The Imaging Science Subsystem (ISS) observed Saturn’s Northern Hemisphere in a search for lightning.

Cassini Outreach and Science Planning (SP) gave presentations to educators from one of this year’s new NASA Explorer Schools, the Johnson Magnet School for Space Exploration and Technology in San Diego, CA. An outdoor evening Saturn Observation Campaign workshop, including “How to Plan a School Star Party,” and “Cassini Top 10 – Mission Overview and Top Science Highlights to Date” were among the presentations.

This San Diego school joins 24 other recently announced NASA Explorer Schools around the country, all aiming to inspire students in science, technology, engineering and mathematics. NASA has a total of 150 Explorer School teams, primarily from minority and under-represented communities, from all 50 states, the District of Columbia and Puerto Rico.

The Aftermarket Process for the S27 sequence began today. This 5-week process will address proposed sequence changes that require re-integration of the segments contained in the S27 sequence. On Wednesday, July 19, if all of the requested changes do not fit within scope, there will be an Assessment meeting with the Project Scientist to prioritize the proposed changes.

Tuesday, July 18 (DOY 199):

A delivery coordination meeting was held today for version 5.2 of the RADAR Synthetic Aperture Radar Processor and Radar Mapping Sequencing Software.

Outreach gave a 1-day workshop on Tour Science updates and “Reading, Writing, and Rings” to 20 educators attending a week-long workshop sponsored by the Bay Area Science Project. The workshop was held at Albany Middle School in Albany, California.

Wednesday, July 19 (DOY 200):

Uplink Operations sent commands to the spacecraft today for ACS to restore the telemetry schedule post-T16 on DOY 203, provide ACS High Z-Sigma error monitor masking for a Tethys flyby on DOY 204, upload a CAPS T16 actuator IEB update, set up the CDS T16 data replay on DOY 204, and update the RADAR IEB trigger for T16. Busy day!

New radar images from Cassini revealed geological features similar to Earth on Xanadu, an Australia-sized, bright region on Saturn’s moon Titan. These radar images, from a strip more than 4500 km long, show Xanadu is surrounded by darker terrain, reminiscent of a freestanding landmass. At the region’s western edge, dark sand dunes give way to land cut by river networks, hills and valleys. These narrow river networks flow onto darker areas, which may be lakes. A crater formed by the impact of an asteroid or by water volcanism is also visible. To access the full story link to:

The fact that OTM-69 is a fairly large deterministic maneuver at 5.4 m/s, and the delivery error at T16 is small, canceling OTM-68 has a small delta V penalty of about 8 mm/sec. Therefore, OTM-68 has been cancelled. The maneuver preparation meeting will be held tomorrow to provide an opportunity to answer any questions team members might have. All other OTM-68 support meetings have been cancelled.

Coming Up:

Friday and Saturday July 21,22

Cassini Outreach will distribute Cassini material and interpret the night sky through telescopes at Yosemite National Park’s Glacier Point Star Party on July 21 and 22. Most every summer weekend, astronomy clubs from California present a sunset talk followed by a star party at this, one of the darkest astronomy sites in the United states. These events are open to the public. All park visitors are welcome to join the park ranger for a sunset and constellation presentation, and then view the summer skies from the Glacier Point amphitheater after dark. Contact if you would like a schedule of 2006 star parties.

Wrap up:

Check out the Cassini web site at for the latest press releases and images.

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.

SpaceRef staff editor.