Cassini Significant Events -- for 09/15/05 - 09/21/05

September 23, 2005

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired Wednesday, September 21,
from the Madrid 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, September 15 (DOY 258):

Yesterday Cassini passed apoapsis and the start of orbit #15. During this
near-apoapsis period, the Magnetospheric and Plasma Science (MAPS)
instruments will conduct a campaign to locate dawn-side magnetospheric
boundaries and to observe plasma waves on the magnetospheric boundary at
various radial distances, as well as continuing to survey the magnetosphere.

As was reported last week, science data was lost as the result of an
improperly set flag preventing the spacecraft from writing to or reading
from the A side of the solid state recorder (SSR). Commands were sent to
the spacecraft today to re-enable SSR-A data recording. Telemetry confirmed
that the files were received by the spacecraft. Now we wait for a normal
data collection period and confirmation that all is well when that data is
played back over tomorrow's pass.

Friday, September 16 (DOY 259):

A press release with Radar images displaying an apparent shoreline on Titan
has been issued. Hints are evident that this area was once wet, or currently
has liquid present. For the full press release and access to the images go

The Spacecraft Operations Office (SCO) sent commands to the spacecraft to
load Composite InfraRed Spectrometer (CIRS) flight software Version 4.0 into
the non-default partitions of both SSRs. Checkout of this software is
planned for mid October.

SCO reported that they were able to verify that SSR-A was the prime SSR
during last night's observation. This means that we are able to
successfully command a swap to SSR-A to record data, and we have regained
the use of both SSRs.

The flight team is gearing up for Orbit Trim Maneuver (OTM) #33. The
preparation meeting was held last Wednesday, and a go ahead was given at an
approval meeting today. The OTM files have been merged with the S14
background sequence and all have been released for use by the flight team.
The maneuver will execute next Monday.

The official port occurred today for the S17 Science Operations Plan (SOP)
Update process. The merged products are currently being run through the
end-to-end pointing validation software by ACS. The Project Briefing and
Waiver Disposition Meeting is scheduled for Wednesday, September 28. The
SOP Update product is handed off to the sequence leads on Friday, September

Monday, September 19 (DOY 262):

On Friday, a kickoff meeting was held for a Live Update to execute on DOY
266-269. A final orbit determination solution was released on Sunday, and
today at the Go/No Go meeting it was decided that the update was still
necessary but only for three Tethys vectors for DOY 266 and 267. When
approved, the files will be uplinked to the spacecraft on Thursday,
September 22.

A Hyperion and Tethys science preview meeting was held to present the
instrument observation plans and science for the upcoming flybys.

Orbit trim maneuver #33 (OTM-33) was successfully completed today. This
apoapsis maneuver sets up Cassini's trajectory for the flyby of Hyperion on
September 26. The main engine burn began at 11:00 am PST. A "quick look"
immediately after the maneuver showed the burn duration was 176.3 sec,
giving a delta-V of approximately 27.8 m/s. All subsystems reported
nominal performance after completion of the burn.

At a Delivery Coordination Meeting SCO delivered version 11.1 of the
Inertial Vector Propagator (IVP) software. This update was specifically
released to fix issues related to the LIVE_IVP_UPDATE features. There are
four outstanding test reports written against the released IVP software
version V11.0 for problems encountered during Live IVP Update activities.

Tuesday, September 20 (DOY 263):

The OTM-34 preparation meeting was held today.

Cassini Outreach presented a poster on "Reading, Writing, and Rings" at the
annual conference for the Astronomical Society of the Pacific meeting in
Tucson, Arizona. The meeting was held September 14-16, 2005. Approximately
350 members of the astronomy education community attended.

As part of the science observation activities this week, the Ultraviolet
Imaging Spectrograph (UVIS) performed a number of mosaics of Saturn's inner
magnetosphere. In addition, the Imaging Science Subsystem (ISS) took
images of Mimas, Enceladus, Tethys, Dione, Rhea, and Iapetus to continue to
map the various satellite longitudes at various phase angles. The other
Optical Remote Sensing (ORS) instruments acquired data on these satellites
as well.

Wednesday, September 21 (DOY 264):

The final sequence products for S15 have been posted to the Program file
repository and are available for review. The sequence approval meeting will
be held on Tuesday, September 27, with uplink of the background sequence and
Instrument Expanded Blocks (IEB) beginning on October 3.

A Radar image of a shoreline on Titan was Astronomy Picture of the Day

An encounter strategy meeting was held for OTMs 35-37, and flybys Hyperion 1
and Dione 1.