Cassini Significant Events -- for 07/28/05 - 08/03/05

August 5, 2005

(Source: Cassini Project)

The most recent spacecraft telemetry was acquired Wednesday, August 3, from
the Madrid 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 the "Present
Position" web page located at .

Activities this week:

Thursday, July 28 (DOY 209):

The Composite Infrared Spectrometer instrument team delivered version 4.0 of
their flight software to the Program Software Library.  A Software
Review/Certification Requirements meeting will be scheduled sometime in
August and the software will be uplinked and an on-board checkout performed
in mid October.

The IGAP/ Kinematic Prediction Tool (KPT) Working Group kicked off today.
This group is comprised of representatives from the Mission Sequence
Subsystem team, Science Planning, SCO, and the Imaging Science Subsystem.
The goal is to devise a way to identify workable solutions that facilitate
the search for moons in Saturn's ring gaps.  One way to achieve this is to
complete mosaics of Saturn's rings by targeting a point as it moves
upstream, producing concatenated overlapping footprints, while compensating
for the motion of the spacecraft.

Uplink Operations (ULO) sent the S13 live Inertial Vector Propagator update,
background sequence, and Instrument Expanded Block (IEB) files to the
spacecraft. All files necessary to support S13 are now on board the
spacecraft.  In addition, commands were sent to power cycle the Magnetometer
Subsystem on Friday, and perform a memory readout for the Ion and Neutral
Mass Spectrometer on Saturday.

Cassini's top ten science highlights for the first year in Saturn orbit are
featured on the Cassini website. Check it out at:

Friday, July 29 (DOY 210):

A Delivery Coordination Meeting was held for the Remote Terminal Interface
Unit (RTIU) V3.3, and the electronic Command Request Form (eCRF) version
1.4.4  The update to RTIU fixes several minor bugs to software that provides
Instrument Teams a CDS/Bus simulator interface to their engineering model
test beds. The eCRF delivery responds to an approved engineering change
request and fixes three minor bugs.

A news release has been issued on the evidence for active ice volcanism
recently observed on Enceladus.  The Cassini spacecraft has found a huge
cloud of water vapor over the moon's south pole, and warm fractures where
evaporating ice probably supplies the vapor cloud. Cassini has also
confirmed Enceladus is the major source of Saturn's largest ring, the
E-ring.  For more details from this release go to the news and media section

Uplink Operations sent commands to the spacecraft for the S13 Live Movable
Block (LMB) files, additional Visual and Infrared Mapping Spectrometer
(VIMS) IEB load and triggers, and the S12 end-of-sequence reaction wheel
assembly (RWA) bias commands.  ULO confirmed that the S13 DOY 214 LMB, VIMS Triggers, and AACS RWA Bias registered nominally on-board the spacecraft, and VIMS team members confirmed successful execution of their IEB Load.

Sunday, July 31 (DOY 212):

The keys to the spacecraft were officially handed over to the S13 leads
today.  S13 runs for 31 days beginning on July 31, and ending on August 30.
During the sequence there will be one targeted encounter of Titan (T6), and
six non-targeted encounters - one each of Mimas, Prometheus, Calypso, Titan,
Tethys, and Telesto. Orbit Trim Maneuvers (OTM) #26, 27, 28, 29, and 30 will
execute, along with one live moveable block, two ground movable blocks, and
two live IVP updates.

Monday, August 1 (DOY 213):

The S16 Science Operations Plan Update process kicked off today.

Waiver and Sequence Change Request disposition meetings were held for both
S14 and S15.

Tuesday, August 2 (DOY 214):

The Rev 12 Radio Science Subsystem (RSS) Saturn/Rings Ingress and Egress
occultation completed successfully today.  This occultation is the sixth out
of eight highly optimized diametric occultations taking place this summer
during Revs 7-14, between May and September, and is the last occultation in
the Cassini Tour that includes both ingress and egress occultations of the
rings and atmosphere.

The occultation was covered by Madrid's DSS-63 for S- and X-band, dual
polarizations, and DSS-55 for X- and Ka-band.  A Goldstone DSS-14 pass that
overlapped with Madrid and started just before the beginning of egress also
captured the egress part of the occultation.  Open loop S- and X-band dual
polarizations data were acquired at DSS-14 as well. As with the previous
occultation, the S-band data were noisy due to solar conjunction. It is at
this time that this signal with the longest wavelength is the most
sensitive. The Sun-Earth-Probe separation angle today is about 7.5 degrees.

Non-targeted flybys occurred today of Mimas, Prometheus, Calypso, and Titan.

The main engine cover was opened today in preparation for OTM-26.  It will
be closed again on August 19 after OTM-28, right before the Titan-6 flyby on
August 22.

It's been a while since I reported it so here is a day in the life of the
flight team as they get ready to support an OTM.  This flow happens for
every OTM.  Only the days and times vary.  The driver is the actual burn
time for the OTM.  Everything counts back from then.

Tuesday, 8/2/05:

2 pm  NAV delivers the final maneuver solution to the Spacecraft
Operations Office (SCO)

2-3 pm  Systems does a final Maneuver Automation Software (MAS) run and publishes the maneuver to the program file repository (DOM)

3 pm  Attitude control (ACS) begins Flight Software Development System testing

3-4 pm  The sequence leads merge the maneuver file with the background sequence, then publish the merged products to DOM

4 pm  The Subsystem leads start checklists on the merged {OTM + background sequence} files

6 pm  NAV & ACS maneuver approval slides are due to the OTM lead

7 pm  Subsystem checklists are due to OTM lead

8 pm  Maneuver Approval Meeting and Command Approval Meetings are held

Wednesday, 8/3/05:

Midnight  on-stations time

0:11 am  Beginning of Track

6:14 am  burn ERT

Wednesday, August 3 (DOY 215):

Orbit trim maneuver #26 (OTM-26), the Enceladus 2 cleanup maneuver, was
completed  today. The main engine burn began at 6:14 am PDT (Earth receive
time).  A "quick look" immediately after the maneuver showed the burn
duration was 16.7 sec long, giving a delta-V of 2.6 m/s. All subsystems
reported nominal performance after execution.

The Magnetospheric Imaging Instrument team gave a Cassini internal Tour
Science Talk today.  The presentation was entitled: "Energetic neutral atom
imaging of Saturn's magnetosphere: Remote sensing isn't just optical".

The S18 Aftermarket assessment meeting was held today.

A delivery coordination meeting was held for the Navigation Ancillary
Information Facility (NAIF) Toolkit N0058.  At this meeting Instrument
Operations delivered the latest toolkit and associated core software.  New
capabilities include support for satellite IDs in the Range 10000-99999,
which allows for more than 99 bodies to be identified in the Saturn System.

Wrap up:

Check out the Cassini web site at for the latest
press releases and images.

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.