Cassini Significant Events 02/18/09 - 02/24/09
The most recent spacecraft telemetry was acquired on Feb. 24 from the
Deep Space Network tracking complex at Goldstone, California. The
Cassini spacecraft is in an excellent state of health. Information on the
present position and speed of the Cassini spacecraft may be found on the
"Present Position" page at:
Wednesday, Feb. 18 (DOY 049)
Spacecraft Operations hosted the S53 Engineering Activities Review
today. At this review the team goes over all engineering and health
and safety activities to be performed during sequence execution.
Thursday, Feb. 19 (DOY 050):
Sequence activities began with a series of Optical Navigation images
collected by the Imaging Subsystem (ISS). These images of Saturn?s
satellites against the background stars allow the Navigation team to more
accurately determine Cassini?s orbit. The day ended with a thirteen-hour
observation of Saturn?s E and G rings by the Visual and Infrared Mapping
Friday, Feb. 20 (DOY 051):
Work continued on preparations for the swap to the RCS thruster B-branch,
scheduled to begin Mar. 12. A technical review of the Cassini
Thruster Swap and Checkout Plan was held today. Representatives
from Divisions 31, 34, and 35 participated.
A detailed review of the "Open LV-41 and swap to B-branch"
procedure was also held today. The Integrated Test Laboratory dry
run will be kicked off Feb. 23. Both the procedure and various
contingency files will be tested that week.
An AACS friction test of the backup reaction wheel # 3 was performed
today. In this test, performed every 6 months, the wheel is spun up
to 600 rpm in both the clockwise and counterclockwise directions, and
timed as it is allowed to run down to zero. Results were unchanged
from previous tests.
Today the Ultraviolet Imaging Spectrograph (UVIS) oriented the spacecraft
to target Enceladus for a three and a half hour observation designed to
map the system in the immediate neighborhood of Enceladus. Observations
tested the connection between volatile changes and plume
eruptions. Next, ISS targeted a few more icy satellites in
the Saturn system. The day ended with an experiment conducted by the
RADAR instrument where, instead of actively bouncing RADAR signals off
Titan, they passively measured the radio heat signature of Titan. This
type of measurement is referred to as radiometry.
Science Planning handed off all files and materials to Uplink Operations
to begin final sequence development for S50.
An after-school adaptation of Reading, Writing & Rings was presented
to 60 Los Angeles area educators on February 19 and 20, 2009.
Educator-Astronaut Barbara Morgan will be the keynote speaker at the
International Reading Association's Annual Convention West in Phoenix,
AZ, February 21-25, 2009. She will feature "Reading, Writing
& Rings" in her address. Cassini Outreach provided copies
of the RWR CD-ROM to her to distribute to 300 teachers attending the
Monday, Feb. 23 (DOY 054):
The Target Working Team (TWT)/ Orbiter Science Team (OST) integrated
products for S53, covering orbits 117 through 119, were delivered today.
The integrated products are in their final form and no re-integration is
planned. The next step in sequence development, Science Operations
Plan (SOP) implementation, will kick off on Mar. 9. Between now and
then, the instrument teams will be working on pointing designs for the
sequence. TWT/OST teams deliver integrated sequence products for the
extended mission about every five weeks.
Tuesday, Feb. 24 (DOY 055):
Contingency planning is one of the many ongoing activities while a
flight project is in the operations phase. A possible scenario
might be that someday the reaction wheels on board Cassini may
fail. That scenario and the options for conducting a thrusters-only
mission was the topic of discussion at the Mission Planning Forum today.
The presentation included Reaction Control Subsystem hydrazine budget
with number of turns per day, different options for articulating the
spacecraft at slower rates and accelerations, wider deadbands, etc.
The February Cassini-Huygens Analysis and Results of the Mission
teleconference for the JPL outreach networks featured "Rings around
a moon? The puzzling case of Rhea." The presentation can be
downloaded from the Cassini website at:
Each year dozens of Cassini scientists, engineers and educators volunteer
to support Open House. In 2009, JPL open house takes place all day
Saturday and Sunday, May 2 and 3. The attached link will take you
to a Cassini specific video from 2008. There are additional videos on the
On Feb. 24, a quadruple transit of Saturn's moons occurred when Titan,
Mimas, Dione and Enceladus passed directly in front of Saturn as seen
from Earth. The Hubble Space Telescope and amateur astronomers from
along the Pacific coast of North America, Alaska, Hawaii, Australia and
East Asia were able to observe this event. Transits like these are rare.
They only happen every 14 to 15 years when the orbits of Saturn's moons
are nearly edge-on to Earth. For more information link to:
To unsubscribe from Cassini Spacecraft Updates or to subscribe with a
different email address, visit:
This email address is not monitored. For comments and questions, please
contact Cassini Outreach at:
Visit the JPL Cassini home page for more information about the Cassini