Cassini Significant Events
for 01/26/06 - 02/01/06
The most recent spacecraft telemetry was acquired Wednesday, February
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
“Present Position” web page located at
Thursday, January 26 (DOY 026):
Picking a target for a spacecraft to observe is usually a task for a
group of mission scientists. This past fall, however, a group of
fourth and fifth graders got to put themselves in the scientists’ place
select where to point Cassini’s cameras as the spacecraft continues its
of the Saturnian region.
The students were given ten days to study three target options and
which opportunity would make the most sense scientifically. After a
debate, they voted to take an image of the rings. The opportunity arose
Cassini mission planners were weeding out a few extra optical
images (OPNAVs) built in the mission plan. OPNAV images are images that
navigators use to learn the exact orbits of the various moons orbiting
ringed planet, as well as the orbit of the spacecraft itself.
The Cassini Program generally builds in a few more images for optical
navigation purposes than are absolutely necessary as a contingency
in case of outages. Since current performance has been excellent, the
Program was able to free up a small number of these images for this
with no cost and no impact to the mission.
The students who got to step into Cassini scientists’ shoes attend
Avenue Elementary School in Reseda, California, part of the NASA
School network. The school was selected to pilot this educational
that challenges students to experience first-hand the kind of decisions
scientists make on a daily bases. On Wednesday, January 25, these
were able to be present at JPL when their image was received and
In February, a similar activity will be open to all 150 NASA Explorer
Friday, January 27 (DOY 027):
The official input port for S20 development occurred today as part of
Science Operations Plan (SOP) update process. The merged products are
currently being run through the end-to-end pointing validation process
AACS. The Project Briefing and Waiver Disposition meeting is scheduled
Wednesday, February 8. The SOP Update product is handed off to the
leads on Friday, February 10.
A Reaction Wheel Assembly (RWA) friction test was performed today on
backup wheel. In this test, the RWA is spun up to 600 RPM in both
directions and is timed as it coasts down to 0 rpm. The results of
test were favorable and showed no significant change since early 2004.
Sequence leads for S18 were informed today that DSS-15 is ready for
operations. Contingency commanding and possible data loss mentioned
last week’s Significant Events report was avoided. Cassini has
the planned downlink schedule.
An image of a new storm on Saturn is Astronomy Picture of the day
But this time, the image was taken, not by Cassini, but by two
astronomers near Paris, France. Interestingly enough, the storm seems
correspond with an outburst of radio noise detected by the Cassini
spacecraft. The phenomenon is likely similar to the Dragon Storm
Cassini’s instruments early last year. That storm is thought to be
to a terrestrial thunderstorm, with radio noise produced in
lightning discharges. Kudos to the guys in France!
Background sequence S18 began execution today. The sequence will run
42 days, concluding on March 10. Operations during that time include
Trim Maneuvers 51, 52, 53, and 54, one targeted outbound flyby of Titan
an altitude of 1,813 km, one non-targeted flyby of Helene at an
67,669 km, two potential live updates, 50 DSN tracks, and a periodic
instrument maintenance activity performed by the Spacecraft Operations
Saturday, January 28 (DOY 028):
Using Deep Space Network station DSS-25, the Radio Science Subsystem
executed a High Gain Antenna Boresight Calibration in preparation for
Titan gravity experiment later in the sequence.
A member of the Cassini Mission Support and Services Office gave a
talk to 20 educators from the Midwest. The educators were visiting
as part of a workshop hosted by Space Education Initiatives.
Monday, January 30 (DOY 030):
The Saturn Observation Campaign (SOC) web pages have been updated for
viewing in 2006. Saturn is back in the early evening sky, and is
visible rising in the eastern sky after sunset. Look to the members
find a Saturn Observation Campaign participant who can help you see
If there is no one in your area, consider participating in this
Cassini Mission Outreach program. Find Saturn viewing information,
roster and participation guidelines on the SOC website at
Weather permitting, public viewing of Saturn will be provided by Saturn
Observation Campaign and Cassini Outreach volunteers with telescopes on
Friday, February 3, on Colorado Blvd in Pasadena, CA and Saturday,
4, at Library Park, Myrtle and Lime Streets, Monrovia, CA. Saturn, just
opposition, will be in our evening sky until June. For more information
access the following URL:
The Satellite Orbiter Science Team sponsored a 2-day Icy Satellite
on January 30-31st in honor of the late JPL scientist Damon Simonelli.
was a very productive science meeting to discuss collaborative science
the icy Saturnian satellites.
Tuesday, January 31 (DOY 031):
The Aftermarket Process for the S22 sequence began today. This 5-week
process will address proposed - discretionary - changes that require
re-integration of the segments contained in the S22 sequence. All such
changes were submitted today and an assessment package released by the
Science Planning Team. It appears that all of the requested changes
within the available resources. Unless the Target Working Teams and
Science Teams’ recommendations change over the next couple of weeks, it
likely that the Decision meeting scheduled for February 15 will be
Outreach presented Cassini education materials, with an emphasis on
Writing, and Rings, to over 300 educators in Orange County. The event
sponsored by the Discovery Science Center in Santa Ana, California.
An illustration of the Huygens Probe on Titan’s surface was Astronomy
Picture of the Day today. This illustration is based on data returned
All teams and offices participated in this month’s NASA Quarterly
In addition to the standard template, special presentations were given
the upcoming changes to the reference trajectory and the resulting
science/sequence re-integration required, spacecraft status and
science data archiving, outreach, status of meeting level-one science
requirements, and science highlights for the quarter.
Uplink Operations sent commands to the spacecraft for the Cosmic Dust
Analyzer decontamination mini-sequence. The mini-sequence will execute
Friday, February 3.
Wednesday, February 1 (DOY 032):
During this first week of S18, Cassini was outbound from Saturn.
Remote Sensing activities included Imaging Science Subsystem (ISS)
spectrophotometry and phase coverage study of Iapetus with the
Imaging Spectrograph (UVIS) riding along to measure the ultraviolet
The distance from Cassini to Iapetus was 942,300 km with the
Sun-Iapetus-Cassini or phase angle at 135 degrees. This was followed
lightning search by ISS and the Visible and Infrared Mapping
(VIMS) in the Saturn northern hemisphere.
ISS also observed three satellite mutual events in which the path of
satellite crosses another during the period of observation. With rapid
shuttering, the time of exact alignment can be captured and
into the astrometric measurements that are a key part of orbit
calculations. The transits observed this week were Rhea across
Titan across Telesto, and Janus across Enceladus. Other images of
satellites, namely Enceladus and Dione, were taken against a star
by the Optical Navigation team. This returned data will be analyzed to
refine knowledge of the spacecraft trajectory as well as the orbits of
The Composite Infrared Spectrometer conducted a lengthy observation of
Saturn measuring oxygen compounds such as H20 and CO2 and hydrocarbons
function of altitude, particularly in Saturn’s stratosphere. Different
latitudes were sampled during the segments of the analysis.
VIMS made a number of stellar calibrations of bright IR stars. These
used to build a library of up to 70 bright stars. Even though these
are very bright, they have not been extensively observed in the near
Since it is now far beyond Earth’s atmosphere, VIMS can measure the 1
micron spectra of stars without being affected by terrestrial water
CO2, CH4 or other contaminants. Observing stars of different spectral
will establish the variation of near-IR spectra according to type.
The Magnetospheric and Plasma Science instruments were also active this
in performing an outer magnetosphere survey. By continuously taking
these instruments seek to establish the locations of the magnetospheric
boundaries, the global dynamics of the magnetosphere, and the degree of
variability with time.
Check out the Cassini web site at http://saturn.jpl.nasa.gov for the
press releases and images.
The Cassini-Huygens mission is a cooperative project of NASA, the
Space Agency and the Italian Space Agency. The Jet Propulsion
division of the California Institute of Technology in Pasadena, manages
Cassini-Huygens mission for NASA’s Science Mission Directorate,
D.C. JPL designed, developed and assembled the Cassini orbiter.