NASA Cassini Significant Events for 07/21/05 – 07/27/05
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.
