Cassini Update - March 18, 2005

Cassini Significant Events
for 03/10/05 - 03/16/05

The most recent spacecraft telemetry was acquired today 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:

Science this week included a magnetospheric boundary campaign performed
by
the Magnetospheric and Plasma Science (MAPS) instruments, and both
individual and joint observations performed by the Optical Remote
Sensing
(ORS) instruments.

Individual ORS observations included Far-IR Maps of Saturn taken by the
Composite InfraRed Spectrometer (CIRS), Visual and Infrared Mapping
Spectrometer (VIMS) observations of the E ring, Ultraviolet Imaging
Spectrograph (UVIS) mosaics of Saturn's inner magnetosphere, and
Imaging
Science Subsystem (ISS) observations of Iapetus limb topography and
geodesy.

VIMS, CIRS and ISS jointly performed radial scans of Saturn's rings as
Cassini crossed the ring plane on March 12, and ISS and UVIS
periodically
performed joint observations of Dione, Enceladus, Mimas, Rhea and
Tethys.

Thursday, March 10:

Uplink Operations sent commands to the spacecraft today for an ISS Wide
Angle Camera memory readout and reload of Instrument Expanded Blocks,
power-off of the backup sun sensor assembly, and a Magnetospheric
Imaging
Instrument (MIMI) Low Energy Magnetospheric Measurement Subsystem
(LEMMS)
power cycle, sensor reset, and diagnostic mini-sequence.

The Spacecraft Operations Office performed a reaction wheel momentum
adjustment.

Navigation delivered the final orbit determination solution for Orbit
Trim
Maneuver (OTM) 17. The actual maneuver will take place tomorrow
evening.

Instrument Operations delivered ISS Flight Software Version 1.4 to the
Project Software Library. A delivery review will be held on April 15,
with
uplink and in-flight test to occur in June.

The Cassini Imaging Team's (ISS) first scientific findings on Saturn's
largest moon, Titan, are being published today in the journal Nature.

Friday, March 11:

OTM-17 was completed on the spacecraft this evening. This maneuver,
also
known as the "E1 + 3 days maneuver", is part of the E1-T7 10-maneuver
optimization chain.

The main engine burn began at 8:31 p.m. PST. A "quick look"
immediately
after the maneuver showed the burn duration was 2.822 sec long, giving
a
delta-V of 0.42 m/s.

ACS reported the burn termination was a "nominal complete" with an
accelerometer cutoff. Propulsion indicated the burn was nominal. Tank
pressures, temperatures, etc, were nominal. This maneuver was
performed in
the "blow-down" mode, where the fuel and oxidizer tanks were not
directly
connected to the helium pressurant source. Thermal reported all
nominal
with temperatures recovering as expected. Power margin throughout the
maneuver was nominal. There was no unexpected CDS or Fault Protection
activity.

Monday, March 14:

Uplink Operations sent real-time commands to the spacecraft for a CDS
memory
readout, to perform Cassini Plasma Spectrometer (CAPS) actuator
diagnostics,
reset the MIMI LEMMS Sensor, and perform an INMS flight software
normalization procedure.

Tuesday, March 15:

Mission Assurance and Huygens Probe Operations presented a paper
entitled
"Collaborative Risk Management for the Cassini-Huygens Probe Mission"
at
last week's IEEE Aerospace Conference. The paper described the
collaborative effort of risk management and risk mitigation employed by
the
project. The talk was well received at the conference and it is hoped
that
the approach implemented by the Cassini-Huygens team will serve as an
example for others who are implementing risk management during critical
phases of mission operations.

Cassini Outreach and Saturn Observation Campaign members participated
in
Community Science Night at La Fetra Elementary School, a K-5 school
with 720
students, in Glendora, CA. In addition to a school science fair,
visitors
passed by a NASA image display, with 3-D glasses and lithographs for
all.
They also enjoyed a petting zoo, and Saturn and moon observations under
perfect skies. The event also included the "Egg Stronauts Egg Drop"
from
atop the tall ladder on a Los Angeles County Fire Truck, and featured
the
kindergarten astronomy class's scale model of the solar system. Over
300
visitors to the telescopes received Saturn trading cards and Cassini
bookmarks.

Cassini Outreach also participated in a science fair at Barnhart School
in
Arcadia, CA. Over 100 students in grades 1-6 submitted projects. The
Los
Angeles Astronomical Society hosted viewing of Saturn and other
celestial
bodies. All science fair participants received Cassini bookmarks.

Wednesday March 16:

An S12 Science Operations Plan Update wavier disposition meeting was
held on
Wednesday. Project Management approved the two waivers under
consideration.

In support of S10, SCO performed an Integrated Test Lab (ITL) test of
the
Titan-5 closest approach sequence for the April 16, 2005 encounter.

The ITL has also been busy performing ACS Flight Software A8.7.2
updates
planned for a late May 2005 uplink. This version will update maneuver
telemetry scale factors to improve visibility during smaller main
engine
maneuvers. A8.7.2 will also update the guidance and control detumble
vectors for more accurate control late in the mission.

Wrap up:

Check out the Cassini web site at http://saturn.jpl.nasa.gov for the
latest
press releases and images. Further updates to the education section and
the
K-4 program pages were posted live this week at
http://saturn.jpl.nasa.gov/education/index.cfm

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.