Cassini Significant Events -- 04/04/07 - 04/10/07

April 12, 2007

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired on Monday, April 9, from
the Goldstone tracking complex. The Cassini spacecraft is in an excellent
state of health and all subsystems are operating normally. Information on
the present position and speed of the Cassini spacecraft may be found on the
"Present Position" web page located at

Wednesday, April 4 (DOY 094):

Using Saturn to provide the necessary target data, the Composite Infrared
Spectrometer (CIRS) has been performing a weeklong checkout exercise of its
new Version 5 instrument flight software. However, due to a data outage
during a pass over DSS-14, CIRS was unable to obtain the results from part
of its regression testing. A mini-sequence will be sent to the spacecraft
on April 12 that will allow the instrument team to re-run the test and
acquire the remaining data. After the test, CIRS returned to the previous
V4.03 operational flight software.

Today Science Planning hosted a review of the Extended Mission Integration
Guidelines and Constraints document. The purpose of this document is to
provide the science target working teams and orbiter science teams with
integration rules that will reduce the workload required to implement the
integrated science plan. This meeting provided the opportunity for the
science instrument teams and any other members of the Cassini Flight Team to
recommend additional constraints for this document.

For the prime mission, the flight team had an advance-planning period that
allowed for early development and integration of the tour sequences to be
flown on-board the spacecraft. In some cases, these sequences have been in
the archive for years waiting for the next step in the development cycle.
For extended mission, this period is reduced to months. There is no advance
planning period. As a result, processes are being combined and streamlined
to allow for quality development in a much shorter period of time.

Thursday, April 5 (DOY 095):

All Teams and Offices supported the Cassini Monthly Management Review.

Friday, April 6 (DOY 096):

There's a new video feature debuting on the JPL web pages today. The new
monthly feature, called "What's Up", will highlight an astronomical viewing
opportunity everyone can enjoy, usually even without a telescope, and
usually in the most light polluted sky.

This month's planet and mission tie-in is Saturn and Cassini. Saturn is a
fantastic target even in the urban jungles. The moon rises from near Venus
on April 21 through April 25, when the moon is above Saturn. Most of the
images in the video came from amateur astronomers in the Saturn Observation
Campaign. The view the video, link to

On the JPL Education Gateway page you can download the sky chart which will
show you where to find Venus and Saturn, and watch the crescent moon rise in
between the two planets later this month. Go to: -- for the chart, link to:

Saturday, April 7 (DOY 097):

Orbit Trim Maneuver (OTM) 103 was performed today. This is the approach
maneuver setting up for the Titan 28 encounter on April 10. The reaction
control subsystem (RCS) burn began at 2:59 PM PST. Telemetry immediately
after the maneuver showed the burn duration was 25.9 seconds, giving a
delta-V of 0.033 m/s. All subsystems reported nominal performance after the

Monday, April 9 (DOY 099):

Back on March 5, it was reported that a meeting had been held to discuss
Radio and Plasma Wave Science (RPWS) whistler observations in future prime
mission sequences. With only nine possible opportunities remaining for this
activity, RPWS was very interested in seeing if the activity could be
accommodated. The first of these RCS activities executed as planned today.
RPWS acquired nearly four hours of plasma wave observations with the
reaction wheels turned off so that the observations were not contaminated by
electrical interference from the wheels. The primary reason for acquiring
these data is to look for signals characteristic of lightning called
whistlers, but other low frequency signals can also be studied in this
configuration without being masked by interference. Searching through the
acquired data for the seconds-long whistlers is a lengthy process; hence, it
is not yet known if any of these were captured. It is clear, though, that
some very interesting data probably related to Saturn's auroras were
acquired and will be of great interest.

Tuesday, April 10 (DOY 100):

Today Cassini flew by Titan today at a speed of 6.2 km/sec, and an altitude
of 990 km for the T28 flyby. Science for the encounter included RADAR
scatterometry, altimetry, and Synthetic Aperture Radar (SAR) observations of
Titan's surface as the hunt for lakes continues. Among the new parts of
familiar terrain to be imaged is the "other side" boundary of the 'black
sea', which could tell scientists more about its size. Additionally, the
radar team has pointed this pass slightly southward so that it will align
with a future altimetry flyby planned for May 12. Additional observations
provided an opportunity for the Optical Remote Sensing instruments to image
the night side of Titan. Imaging Science Subsystem took observations for
lightning and aurora, Visual and Infrared Mapping Spectrometer did cloud
mapping, and the Ultraviolet Imaging Spectrograph took data for an
ultraviolet mosaic.

Astronomy Picture of the day today featured a not often seen view of the
underside of Saturn.