Cassini Significant Events 08/17/06 – 08/23/06

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

August 25, 2006

(Source: Cassini Project)

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
http://saturn.jpl.nasa.gov/operations/present-position.cfm .

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 http://saturn.jpl.nasa.gov 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.