Cassini Update - April 15, 2005

Cassini Significant Events
for 04/07/05 - 04/13/05

The most recent spacecraft telemetry was acquired Wednesday from the
Goldstone tracking station. 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/operation...t-position.cfm .

Activities this week:

The final science activities in S09 included several magnetospheric
boundary
and solar wind campaigns performed by the Magnetospheric and Plasma
Science
(MAPS) instruments. In addition the Composite InfraRed Spectrometer
(CIRS)
and Visual and Infrared Mapping Spectrometer (VIMS) took data for the
joint
creation of far-IR maps of Saturn.

At the start of this first week of S10 execution, Magnetospheric
Imaging
Instrument performed a Solar Wind Magnetospheric Boundary Campaign,
Imaging
Science Subsystem (ISS) obtained an ansa movie of the F ring at high
resolution/low phase, Ultraviolet Imaging Spectrograph observed a
Saturn
occultation of Delta Orionis, and RADAR performed three separate
polarization measurements of the rings and Saturn. Other atmospheric
observations included VIMS observations of the occultation of Alp CMi
by
Saturn and of the high phase limb.

Thursday, April 7:

This is very much a bits-and-pieces kind of day with many events
occurring
both in development and operations. It gives a good idea of what a day
in
the life of a flight project is like.

All teams and offices supported the Cassini Monthly Management review.

Uplink Operations completed radiation of all files in preparation for
the
start of S10 execution tomorrow evening.

RADAR performed an engineering test on-board the spacecraft.

The files for the S10 Live Inertial Vector Propagator (IVP) update that
will
execute on April 14 were successfully tested in the Integrated Test
Laboratory and the output products published in the project file
repository.

Cassini Outreach participated in the National Council for the Teachers
of
Mathematics (NCTM) Conference in Anaheim, CA April 6-9, 2005. Outreach
staffed the JPL booth, interacting with math teachers at the
conference.
Outreach also attended a variety of professional sessions on teaching
different aspects of mathematics as well as current trends in
mathematics
education.

Friday, April 8:

The keys to the spacecraft were officially handed over today by the S09
sequence leads to those leading S10. S10 contains the first multi-day,
multi-vector IVP update, the second live moveable block performed
during
tour, the first being for Phoebe in June 2004, four OTMs, one targeted
encounter - Titan 5, and 5 non-targeted encounters of Epimetheus,
Mimas,
Calypso, Tethys, and Titan.

Navigation delivered the final Orbit Determination solution for OTM-21.
The
command approval meeting, uplink, and execution will occur tomorrow.

Delivery Coordination Meetings were held for the Inertial Vector
Propagator
(IVP) V10.6, and E-Kernel Generation software v2.

The Science Operations Plan Update process has concluded for sequence
S12.
Output products have been handed off to the sequence developers for
next
week's start of the Science and Sequence Update process.

Saturday, April 9:

Orbit trim maneuver #21 (OTM-21) was completed this evening.

The main engine burn began at 8:15 p.m. PST. A "quick look"
immediately
after the maneuver showed the burn duration was 37.35 sec long, giving
a
delta-V of 5.82 m/s. All subsystems reported nominal performance.

April 9 was an extremely happy day for the Ion and Neutral Mass
Spectrometer
(INMS) instrument team as they declared their "unexpected reboot"
problem
officially solved.

In August of 2003, INMS powered on during the C39 sequence for the
first
time since launch in October 1997. Near the end of this sequence they
experienced an unexpected reboot of the instrument. During the course
of
the following sequences - C40 and C42- they again experienced
unexpected
reboots.

In an attempt to debug and gather information about the problem, three
special flight software loads were built and uplinked between January
and
March of 2004 during the execution of the C42 and C43 sequences.

As a result of these special flight software "builds", the INMS
engineers
were able to determine that the source of the problem had to do with
the
interaction with the Bus Interface Unit (BIU). A few patches to change
the
way INMS interacts with the BIU were uplinked following this discovery.
Unfortunately, the patches were not successful in fixing the problem.

It was then decided that adding an ability to interact with the BIU
using a
double buffering approach instead of the single buffer approach was the
next
option to examine. Within a short period of time this was determined
to be
a viable solution. Double buffering could not be built as a patch to
flight
software (FSW), so version 9.1 was built, uplinked, and tested during
the
S04 sequence in September 2004. During the S05 through S08 sequences,
this
new version of FSW was used routinely and no unexpected resets of the
instrument occurred.

It had been decided previously that INMS would only declare the
unexpected
reboot problem resolved if the instrument ran without incident for more
than
40 days. It was not until March 2005 during S09 that INMS was able to
acquire a period of time of more than 40 days to be able to perform
this
test. This period was selected as it was a time where an unexpected
INMS
science loss due to another reset was deemed an acceptable risk.
Today,
April 9, upon the conclusion of S09, INMS has successfully run without
a
reset for over 41 days.

One year and eight months after the initial occurrence of the problem
in
C39, the INMS engineering, operations, and science teams have declared
victory!

The reboot problem was well documented and publicized. The resolution
was a
huge effort by a small and extremely talented group from the University
of
Michigan where the INMS Operations Team makes its home. INMS personnel
wish
to thank all those at JPL and on the Cassini Flight Team who assisted
along
the way with resolving this problem.

Monday, April 11:

A kick-off meeting was held today for the Science Operations Plan
Update
(SOPU) process for S13. The S13 process marks the return of SOPU to a
5-week activity. S09 through S12 were the first sequences that
underwent
advance development in the SOP Implementation (SOPI) process back in
May
2002. As SOPI was exercised by the sequence developers, a number of
changes
were identified as necessary during SOPU. The S09-S13 products were
archived, and plans were made to extend the S09 through S12 SOPU
process
durations to 10 weeks to allow for these additional changes.

Uplink Operations radiated Live Update commands to the spacecraft. The
commands will execute next week on April 14. In addition, memory
readouts
(MRO) were obtained for all partitions, the actions log,
non-interfering,
and interfering error logs.

Updated SPICE Rocks SPK & PCK Kernel files have been released for
Science
Planning use.

Tuesday, April 12:

The Software Requirements and Certification Review for Cassini Plasma
Spectrometer (CAPS) version 4.1.0 flight software (FSW) was held today.
The
FSW was approved with no pending action items. Uplink is currently
scheduled
for the May 22/23 time frame. S11 sequence leads and members of the
Spacecraft Operations Office are currently working final uplink dates.
FSW
checkout is tentatively planned for May 26/27.

S12 began final sequence development today. In addition, the Live
Update
Working group met this morning and decided that a local update was no
longer
a feasible option for S12. The current reference trajectory is the
best
available baseline for developing the sequence. The team will proceed
with
the Live IVP Update strategy as identified in the summary table
produced by
the working group. The S12 leads have accepted the proposed live
update
schedule.

Wednesday, April 13:

Remember how I said last week that the flight team would be pulling off
three OTMs in 10 days? Well, here is number two. OTM-22 was
successfully
completed tonight. This maneuver, also called the "T5 minus 3 day
maneuver," further refines Cassini's trajectory for the 1,025 km flyby
of
Titan on April 16. This will be the closest Titan flyby to date.

The reaction control system burn began at 8:55 p.m. PST. The "quick
look"
immediately after the maneuver showed the burn duration was 67.6 sec,
giving
a delta-V of approximately 63.5 mm/s. All subsystems are nominal.

Cassini Outreach participated in an astronomy night for disabled
students at
Cal State University-Northridge this week. A Braille trail scale model
of
the solar system was set up and Cassini outreach led the " solar system
walk" accompanied by an American Sign Language interpreter. A Braille
planisphere, moon and solar system tactiles, and even a tactile Cassini
Spacecraft model were available for the sight impaired. The moon,
Saturn
and Jupiter were viewed through wheelchair accessible telescopes
provided by
Cassini outreach and the University's observatory. All participants
also saw
a planetarium show about the spring night sky.

Wrap up:

The Cassini website has received a Webby nomination for best science
website! The Webby Awards is the leading international award event
honoring
excellence in Web design, functionality and creativity. Established in
1996
during the web's infancy, the Webbys are presented by The International
Academy of Digital Arts and Sciences, a 500-member body of leading web
experts, business figures, luminaries, visionaries and creative
celebrities.
The Ninth Annual Webby Awards Nominees were announced on April 12 and
winners will be unveiled in May 3.

Saturn Observation Campaign and the Old Town Sidewalk Astronomers will
show
Saturn, the first quarter moon and Jupiter in Pasadena on Colorado
Blvd.
between Fair Oaks and Pasadena Avenue Friday April 15 8-10 p.m, and in
Monrovia at Myrtle and Lime streets Saturday night April 16 from 8 - 10
p.m.

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.