Cassini Significant Events 02/07/07 - 02/13/07

February 16, 2007

(Source: NASA/JPL)

The most recent spacecraft telemetry was acquired on Tuesday,
February 13, from the Goldstone tracking complex. The Cassini
spacecraft is in an excellent state of health and all subsystems are
operating normally. Check out the Cassini web site at for the latest press releases and images.

Wednesday, February 7 (DOY 038):

Orbit Trim Maneuver (OTM) #93 was performed today. This is the
apoapsis maneuver setting up for the Titan 25 encounter on Feb. 22.
The main engine burn began at 1:45 AM PST. Telemetry immediately
after the maneuver showed the burn duration was 1.52 seconds, giving
a delta-V of 0.26 m/s. On January 26, OTM-91 was reported as the
smallest reaction control subsystem maneuver to date. Well, not to
be out done, OTM-93 is now the smallest main engine maneuver to date.
The previous record holder was OTM-25, with a burn of 2.1 seconds and
a delta-V of 0.34 m/sec. All subsystems reported nominal performance
after the maneuver.

Images of five small satellites, Prometheus, Atlas, Pandora, Dione,
and Janus, were taken today with the goal of improving knowledge of
their orbits.

The majority of today was spent alternating back and forth between
additional Saturn high latitude Visual and Infrared Mapping
Spectrometer (VIMS) photopolarimetry and Ultraviolet Imaging
Spectrograph (UVIS) auroral observations. This is part of the Hubble
Space Telescope/Cassini International Heliophysical Year campaign.

Both Hubble and Cassini have previously imaged Saturn's auroras,
demonstrating that they vary in latitudinal position and extent and
that they alter rapidly as conditions in the solar wind change due to
activity on the Sun. Repeated observations today will help to
understand how the auroras respond to the solar wind. Inferences can
also be made about the upper atmosphere of Saturn and its interaction
with the magnetic field.

The Cassini Deputy Program Scientist gave an in-reach talk today to
members of the flight team. Every quarter, Cassini gives a
presentation on project status to NASA personnel. One part of that
presentation includes the most significant science results from the
previous three months. Over the last year, the flight team has
requested that this presentation also be given internally to project

A beautiful RADAR image of the liquid methane lakes on Titan is
Astronomy Picture of the Day today.

A delivery coordination meeting was held today for the Cassini
Information Management System version 3.3.2. This update supports
Oracle 10G and contains modifications to the Resource Checker process.

Thursday, February 8 (DOY 039):

An encounter strategy meeting was held today for the Titan 25 and
Titan 26 flybys. The meeting will cover the period from Feb. 22
through March 19, and Orbit Trim Maneuvers 95-97.

The kickoff meeting for the Hyperion live update was held today. The
update will execute over DOY 046-047. Teams have been reporting the
need for this update so the Go/No-Go meeting scheduled for tomorrow
has been cancelled. It's a Go.

Friday, February 9 (DOY 040):

The Navigation team released an update of the prime mission reference
trajectory to the Project today. The two main purposes for this
update to the trajectory are to raise the Titan-32 periapsis altitude
from 950 km to 975 km, and to change the September Iapetus encounter
B-plane angle from 156.7 to 176.4 deg to improving the viewing
geometry over the equatorial ridge.

A delivery coordination meeting was held today for the Spacecraft
Operations Office Inertial Vector Propagation tool (IVP) V12.1. The
IVP tool is a ground software program for the Cassini attitude
control and science teams, providing precision vector propagation for
desired scientific and engineering targets.

The first worldwide Saturn Observation Night was held Feb 10, 2007.
Members of the Saturn Observation Campaign around the world aimed
telescopes at Saturn, or gathered students in classrooms for Saturn
art and science activities. Newspaper articles, web blogs, reports,
pictures and stories are coming in to Cassini Outreach this week. So
far reports are in from 75 individuals in 13 states and 13 countries,
with many more reports of past events and plans for future events
expected. Go to: for a
NASA News Feature on the event. To find out where other Saturn
viewing events are occurring in the next months, check:

Sunday, February 11 (DOY 042):

An AACS friction test of reaction wheels number 1, 2, and 4 was
executed on board the spacecraft today. This test is performed every
three months. The wheels are spun up to 900 rpm in both directions
and are timed as they run down to zero. Compared to the last test on
Nov. 15, 2006, RWA-1 showed a slight improvement in the clockwise
direction and degradation in the counter-clockwise direction. RWA-2
was only slightly worse in the clockwise direction and unchanged in
the counter clockwise direction. RWA-4 improved slightly in the
clockwise direction and was unchanged in the counter-clockwise

Monday, February 12 (DOY 043):

Cassini Outreach chaired a panel at the 2007 Space Technology and
Applications International Forum (STAIF) conference this week, and
participated on a plenary panel for STAIF in Albuquerque, New Mexico
along with the NASA Associate Administrator for Education, the
Director of Los Alamos National Laboratory, and the Director of
Sandia National Laboratories. The topic was "Inspiring the Next

Tuesday, February 13 (DOY 044):

A final approval meeting was held today for the S28 background
sequence. The sequence was approved and uplink has begun of the
Instrument Expanded Block files to support the sequence. All uplinks
will be complete by Friday, Feb. 16, and the sequence begins
execution early Saturday morning, Feb. 17.

Eclipse entry was the first of several upcoming observations of
Iapetus. This instance is unique because the satellite enters eclipse
through the shadow of the rings, but departs tomorrow from behind
Saturn. The Composite Infrared Spectrometer (CIRS) was the prime
instrument measuring heating and cooling caused by the solar eclipse
to provide information on surface thermal inertia. VIMS provided
supporting measurements of the bolometric Bond albedo, i.e. the
fraction of the total incident radiation energy that is reflected,
and the Imaging Science Subsystem provided supporting imagery.