6 min read

Significant Event Report for Week Ending 10/29/2004

Cassini Significant Event Report

For Week Ending 10/29/04

The most recent spacecraft telemetry was acquired from the Madrid tracking station on Wednesday, October 27. 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 .

It has been a very exciting week for Cassini Program team members. The big news is of course the Titan-a flyby that occurred on Tuesday, October 26. A number of events led up to this extremely successful flyby.

On Wednesday, October 20, the sequence leads for S05 uplinked 13 files to the spacecraft. Most of them were Instrument Expanded Block files necessary for science support of the flyby that would occur six days later.

On Friday, October 22, Science Planning hosted a Titan-A Preview meeting. The meeting opened with an overview of the geometry of the flyby, and several screenings of an animation illustrating the approach, flyby, and departure while illustrating science observations and data collection as they occurred. The overview was followed by presentations by Composite Infrared Spectrometer (CIRS), Ultraviolet Imaging Spectrograph (UVIS), Ion and Neutral Mass Spectrometer (INMS), Imaging Science Subsystem (ISS), Visual and Infrared Mapping Spectrometer (VIMS), RADAR, Cassini Plasma Spectrometer (CAPS), Magnetospheric and Plasma Science (MAPS), Magnetometer Subsystem (MAG), and Radio and Plasma Wave Science (RPWS) instrument teams. Presentations covered the science to be performed for this encounter.

Orbital trim maneuver #4 (OTM-4), the Titan-A approach maneuver, was successfully completed on the spacecraft on Saturday, October 23. This maneuver was performed to ensure accurate trajectory control to Titan.

The burn began at 00:29:28 Pacific Time. A "quick look" immediately after the maneuver showed the burn duration was 7 min 47 seconds, giving a delta-V of 0.38 m/s. This was the longest duration reaction control system (RCS) maneuver performed to date. This was also the first OTM performed using the new ACS flight software version A8.7.1. The last RCS maneuver was TCM-19a on 9/10/03. All maneuvers since that date have been main engine burns.

The success of the Titan-a flyby depended heavily on support from the Deep Space Station complex in Madrid, Spain, since the majority of the data playbacks were to be performed over DSS-63. Cassini Mission Support & Services Office (MSSO) personnel reported that the weather forecast for Madrid included low clouds and light rain. Heavy rains could cause the loss of much or all of the science data. Fortunately, the weather was as predicted. Light rains only, and the station was able to function as planned.

The Cassini spacecraft sent back detailed pictures, spectra and radar data on Tuesday night October 26, during its first close flyby of Saturn's largest moon Titan. The spacecraft successfully skimmed the hazy, smoggy atmosphere of Titan, coming within 1,176 kilometers of Titan's surface. The flyby was the closest that any spacecraft has ever come to Titan. The pictures, spectra and radar data revealed a complex, puzzling surface. Analysis of the data is continuing.

Imaging the surface of Titan was the first time the RADAR instrument had been used to collect science data in the Tour. The science community and the public waited in anticipation for the first opportunity to view the images at the Thursday, October 28 press conference. The first swath of the planet covered approximately 1% of its surface. By the end of the prime mission, the Radar instrument will have taken images of approximately 25% of this satellite.

The only glitch during the T-a event involved the CIRS instrument. During playback the instrument team observed corrupted data. A decision was made to power the instrument off to reboot it. CIRS was powered back on within 24 hours and is currently in its nominal state. Although the problem is still under investigation, the most likely cause of the data corruption was a bad trigger command. Analysis of the CIRS data packets has begun to determine which were corrupted by the problem.

In the same week as the flyby, JPL hosted the thirty-fifth Project Science Group (PSG) meeting. Having the PSG meeting and Titan-a flyby coincide has provided an opportunity for scientists of different disciplines to hold discussions and examine their data as it arrives on the ground.

The excitement of the public over the Titan encounter was evident in the traffic to the Cassini Mission website. The site logged 13.4 million hits on Tuesday, October 26. This is more than double the average traffic for other days in October. Hits as of October 26 were 128 million with 278,202 unique visitors. Images and the Raw Image Gallery are the most popular areas. The "Cassini Present Position" also remains a public favorite.

The 9AM-10AM PST (12-1 EST) Oct. 27th press conference generated the heaviest traffic to the site. As of October 27, Wednesday at noon, the Titan-A Mission Description has been downloaded 74,588 times in the five days it has been on the site.

Information, images, articles, and news releases on the Cassini-Huygens mission are available at http://saturn.jpl.nasa.gov and http://www.nasa.gov/cassini .

In the same week that all these events were occurring, Cassini personnel were supporting a number of other activities. Sequence development is ongoing with a number of milestones met by Science Planning and Uplink Operations that will be reported on next week.

Members of the MSSO went out to the DSN complex in Goldstone, California this week to run a regularly scheduled test of the Cassini Emergency Command Center. The center is provided to the project for use in the event of an emergency where commanding is not possible at the JPL facility in Pasadena. Telemetry was delivered and processed from station DSS-15 during that day's support pass. Additionally, data rates and monitor data were confirmed. The test was successful.

Outreach and a RADAR team member participated in a joint NASA-National Park Service (NPS) workshop at NASA Ames October 18-22, 2004. The workshop was sponsored by the Sun-Earth Connection Forum.

On Saturday 23 October 2004, Spacecraft Operations and VIMS personnel gave two lectures at a Girl Scout Camp in Altadena, California. Eighty scouts attended the talks.

A photo essay produced from images taken by NASA's Cassini spacecraft, orbiting the ringed world since June 30, 2004 is now available on the website. This new multimedia presentation from NASA's Jet Propulsion Laboratory also includes an image gallery and science section highlighting the mission's early stages of exploration. This feature is available in Flash and HTML.

Extensive information on the Cassini-Huygens mission including an electronic copy of the press kit, press releases, fact sheets, status reports, briefing schedule and images is available on the Internet at http://saturn.jpl.nasa.gov