NASA Cassini Significant Events for 10/20/04 – 10/27/04
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.
http://www.jpl.nasa.gov/multimedia/cassini-essay/
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
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.
