Cassini Significant Events for 08/17/06 - 08/23/06

Cassini Significant Events for 08/17/06 - 08/23/06

The most recent spacecraft telemetry was acquired Wednesday, August 23, 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, August 17 (DOY 229):

Today the instrument teams had the closest view of the Saturnian satellite Helene since the start of the mission. Cassini flew by for a non-targeted encounter at an altitude of 48759 kilometers, traveling at a speed of around 7.7 kilometers per second. For this event the Imaging Science Subsystem (ISS), Composite Infrared Spectrometer (CIRS), and Ultraviolet Imaging Spectrograph (UVIS) observed Helene to obtain color, polarization, shape, and geology measurements.

Also today the second Enceladus Plume Debris working group meeting was held. The primary goal of this group is to characterize the Enceladus plumes so that the orbit 61 flyby can be designed to provide excellent Enceladus science without presenting a hazard to the spacecraft. The work of this group is also important for creation and analysis of proposed extended mission tours. The group needs to develop an engineering model incorporating dust and gas that can be folded into Mission Planning and Navigation software for planning flyby scenarios.

Friday, August 18 (DOY 230):

A non-targeted flyby of Titan occurred today.

The preliminary port of the Science Operations Plan update process occurred today for inputs to the S26 sequence. The inputs have been merged, analyzed, and status delivered to the teams for review. The official port is scheduled for Thursday, August 24.

For the final week of S22, the Cassini Plasma Spectrometer (CAPS), Cosmic Dust Analyzer (CDA), Ion and Neutral Mass Spectrometer (INMS), Magnetometer Subsystem (MAG), Magnetospheric Imaging Instrument (MIMI), and Radio and Plasma Wave Science (RPWS) instrument continued to perform simultaneous magnetospheric surveys to observe the variability of magnetospheric boundaries at a variety of radial distances. Several of these instruments also participated in a campaign to study the interactions between icy satellites, rings, and the magnetosphere. MIMI also imaged the dynamics of the inner magnetosphere by sampling energetic ions with the Ion and Neutral Camera sensor.

The Spacecraft Operations Office hosted the S28 Engineering Activities Review. The objective of the meeting is for the Navigation and Spacecraft teams to identify any periods where the mission is particularly vulnerable to a missed Orbit Trim Maneuver during the sequence, and to consider additional contingency plans, if needed. The principal participants are the Navigation and Spacecraft teams, but other offices are also represented.

Saturday, August 19 (DOY 231):

The Traveling Wave Tube Amplifier (TWTA) B line B solid-state power switch (SSPS) changed state from OFF to tripped at 231T09:13:20 SCET, Saturday, August 19. This event had no effect on TWTA operation as line B is normally unpowered, and the trip was determined to have no affect on possible System Fault Protection (SFP) activity going forward. The most recent trip prior to this event was on June 21 for the SSPS on the Stellar Reference Unit (SRU) -B replacement heater. This latest trip is the 18th occurrence since launch, the fourth this year. These trips are expected to occur at a rate of about two per year and are attributed to Galactic Cosmic Rays. The SSPS was reset via real time commanding on Wednesday, August 23.

The keys to the spacecraft were handed over to the sequence leads for S23 today. The background sequence began execution at 2006-231T22:06:00.000. S23 will run for 32 days from August 19 through September 20. During the sequence there will be one targeted flyby of Titan (T17) at 1000 kilometers, four non-targeted flybys, one each of Methone, Calypso, Atlas, and Enceladus, orbit trim maneuvers number 70, 71, and 72, one ring plane crossing, two possible live updates, and a Saturn solar occultation on DOY 258.

At the top of the S23 sequence, three images were taken of Saturn’s satellites that will be used by the Optical Navigation team to accurately calibrate Cassini’s reference trajectory. The Ultraviolet Imaging Spectrograph (UVIS), Imaging Science Subsystem (ISS), and the Visible and Infrared Mapping Spectrometer (VIMS) jointly observed Mimas for 7 hours. UVIS is searching for a possible atmosphere on this icy satellite.

Monday, August 21 (DOY 233):

Recently Cassini Outreach launched an RSS feed. There is now an orange “RSS” button on the home page on the left. Next to it is a link to a help page that will help you get started. RSS in this case stands for “Really Simple Syndication.” It is a mechanism that delivers the latest content from a web site directly to you rather than you having to check the website every day for what’s new. RSS delivers a headline, a short summary and a link to the full text on the website, making it easy to keep up-to-date on your favorite websites. On the Cassini website, RSS is used to deliver the latest information about images, videos, and news coming from the Cassini spacecraft. Go to and look for the orange rectangular button on the left labeled RSS.

UVIS performed several slow scans across Saturn’s visible hemisphere. Following this 10.5-hour activity, ISS used the Narrow Angle Camera to photograph Titan at 140 degrees phase.

Tuesday, August 22 (DOY 234):

A Mission Planning Forum was held today to review and discuss the results of a study of all Titan Orbiter Science Team requested double playbacks, the potential effects on other segments, a process for the playbacks, and recommendations.

The RADAR team obtained 2.5 hours of science and calibration by collecting radiometer data of distant Titan. This activity was one of a set that provides coverage of Titan’s northern latitudinal variation. RADAR also performed a nine-hour calibration activity by scanning the Sun, Saturn, and other microwave sources while collecting radiometry data. In addition, the spacecraft performed a 6.5-hour roll about its X-axis during a periodic calibration for MAG.

Wednesday, August 23 (DOY 235):

The Command and Data Subsystem (CDS) turned off the Cosmic Dust Analyzer (CDA) instrument on Sunday 20, August 20, during an instrument flight software test. CDA was powered “on” today, and is now running on version 10.0 of CDA flight software.

A Delivery Coordination Meeting was held today for the version 3.3.1 patch for the Cassini Information Management System (CIMS). The patch contains a fix to the Science Planning Attitude Spread Sheet / Spacecraft Activity Sequence File comparison process, a performance enhancement for the “delivery” feature, and some usability updates. There are no updates to the CIMS Toolkit. The software was installed today and is now being used in operations.

The Magnetospheric and Plasma Science (MAPS) instruments performed a 6.25-hour low latitude observation of the structure and dynamics of Saturn’s magnetotail, and ISS began a series of periodic, one-hour observations of Saturn’s northern hemisphere in a search for lightning.

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 Spsce 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.