Cassini Significant Events -- for 07/21/05 - 07/27/05

July 29, 2005

(Source: Cassini Project)


The most recent spacecraft telemetry was acquired Wednesday, July 27, from
the Goldstonetracking 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
http://saturn.jpl.nasa.gov/operations/present-position.cfm .

Activities this week:

Thursday, July 21 (DOY 202):

The live IVP update kick-off meeting for DOY 212 was held today. Targets
listed in the kick-off package are Mimas, Dione, Rhea, Saturn, and Tethys.
Additional rocks being observed during the update period are Pallene, Atlas,
Janus, Epimetheus, Pan, Pandora, Telesto, and Prometheus.

A special meeting was held today to present the results of a study comparing
the actual data volume used by the science instruments, against the data
volume allocated to the instrument in the data policing tables. This study
is the result of work done by Science Planning and looks specifically at the
S08 and S10 sequences. It is anticipated that the Target Working Teams and
Orbiter Science Teams will work with the instrument teams to better optimize
the bit allocations.

The Solar Conjunction separation angle reached two degrees today. With the
Sun between the spacecraft and Earth, Cassini has entered a period of
communications degradation lasting approximately seven days. Science this
week was limited to Magnetospheric and Plasma Science instruments, as they
took measurements of both the bow shock and magnetopause to study their
structure in detail.

Cassini Outreach presented a Saturn Observation Campaign workshop, which
included "how to plan a school star party". Twenty five new Los Angeles
area NASA Explorer School teachers attended, then held their own star party
and observed the night sky.

Friday, July 22 (DOY 203):

A really nice shot of Tethys with Saturn is Astronomy Picture of the Day
today.

The Encounter Strategy Meeting for Enceladus 2 through Titan 6 and OTMs 26
through 28 occurred today.

Saturday, July 23 (DOY 204):

Minimum Sun-Cassini separation angle of 0.3 degrees occurred today.

Apoapsis occurred marking the start of Cassini's 12th orbit around Saturn.

Sunday, July 24 (DOY 205):

Radio and Plasma Wave Science (RPWS) observed a strong solar Type II burst
at ~15 hr UT on July 24 (DOY 205). This Type II is probably from solar
active region AR0786 that is on the backside of the Sun as seen from Earth
but front side for Cassini. This region has been extremely active over the
past several weeks. SOHO reports a full backside halo CME at the
appropriate light time corrected to account for the RPWS observation.
Estimated launch speed is 3000 km/sec.

The shock, if it propagates to 9 AU, is predicted to arrive at Saturn August
2-4, with an arrival date of August 4 for minimum deceleration conditions.
The big uncertainty on this one is the launch speed since it's backside and
only a flank is visible in the image. The WIND/WAVES team measured the same
radio burst from 1 AU and got a slower shock speed of 1750 km/sec instead of
3000 km/sec, which means that the shock would not reach Saturn until about 6
August.

Monday, July 25 (DOY 206):

An end-to-end test was run in the Integrated Test Laboratory this week using
the 050505 reference trajectory to test flight software patches for CDS and
AACS, the Titan 7 flyby, a representative orbit trim maneuver, and other
changes.
In mid-August we will test the Titan 7 portion again with the new 050720
reference trajectory released on July 18. The Spacecraft Operations Office
plans to uplink both patches in the early September timeframe.

The final sequence approval meeting for S13 was held. Uplinks of the
Instrument Expanded Block files and the background sequence will begin on
July 27.

JPL has put out a news release regarding Cassini's observations of the radio
emissions of Saturn. Apparently the emissions are quite eerie, could be
mistaken for a Halloween sound track, and are descriptive of a phenomenon
similar to Earth's northern lights according to findings published in the
July 23 issue of the Geophysical Research Letters. The full news release
along with samples of the sounds can be viewed/heard at
http://saturn.jpl.nasa.gov

Tuesday, July 26 (DOY 207):

No new waiver requests have been submitted for the S14 preliminary sequence
phase 1, so the waiver disposition meeting scheduled for today was
cancelled.

Reaction Wheel status at launch + 7.8 years, a status report on Langley
atmospheric drag simulations for Titan flybys, and a summary of Radio
Science requests for DSN tracking submitted for 2006 were discussed at a
Mission Planning Forum held today.

The S15 Science and Sequence Update Process (SSUP) Kickoff Meeting was held
this morning. Following the meeting the stripped subsequence files were
published to the program file repository for team review.

JPL put out an additional press release this week regarding unusual geology
observed on Enceladus during the flyby last week. Detailed images of the
South Polar Region reveal distinctive geological features and the most
youthful terrain seen on that moon. These findings point to a very complex
evolutionary history. To review the images and the text of this press
release go to http://saturn.jpl.nasa.gov

An image of spongy looking Hyperion was Astronomy Picture of the day today.

Cassini Outreach was interviewed for a new local Public Broadcast radio show
called "After Sunset" which aired July 26.

Cassini exited the period of solar conjunction today. Separation angle
reached 4 degrees and the final non-operational commands were sent for
purposes of link characterization. Instrument real-time commanding and
science acquisition - put on hold for the last seven days - will now
recommence at pre-conjunction levels.

Wednesday, July 27 (DOY 208):

A Delivery Coordination Meeting was held for Telecom Forecaster Predictor
Version 4.0. Although there were a number of changes, the most significant
ones were updated DSN station models to include the new X/X/Ka feed.

Science Planning hosted a Cassini internal Tour Science Talk covering
Iapetus and Enceladus data, and Iapetus formation.

Uplink Operations sent five instrument expanded block files to the
spacecraft in preparation for the start of S13 execution. Based on SSR
memory read-outs, it was verified that the spacecraft properly received all
the loads.

Wrap up:

Check out the Cassini web site at http://saturn.jpl.nasa.gov 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.





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