Cassini Significant Events 06/13/07 - 06/19/07
June 22, 2007
(Source: Cassini Project)
The most recent spacecraft telemetry was acquired on Tuesday, June 19, 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 http://saturn.jpl.nasa.gov/operations/present-position.cfm.
Wednesday, June 13 (DOY 164):
This week, Cassini returned to Titan for its thirty-third targeted encounter with that moon. Closest approach was at 965 km altitude, latitude 84.5° N - near the north pole, traveling at a speed of 6.2 kilometers per second, and with a peak thruster duty cycle at 53.8%.
This was the first dual data playback with the recorder SSR-B as prime.
T32 is the eighth in a series of nine outbound Titan encounters. The first was T25 on Feb. 22, 2007, and the last is T33 on June 29, 2007.
The flyby occurred just under two days after Saturn closest approach, and is the highest latitude Titan pass on which the Ion and Neutral Mass Spectrometer (INMS) will be the prime instrument. It is the only pass that occurs close to midnight local time, on the ram side of Titan, while Titan is on the sunlit side of Saturn. This is a magnificent opportunity for in situ science of Titan's atmosphere in this unique geometry.
The Imaging Science Subsystem (ISS) performed high-resolution imaging and global-scale mapping of the bright-dark boundary, and the Visual and Infrared Mapping Spectrometer (VIMS) performed high resolution mapping of Titan's north pole for global mapping, did temporal change studies of Titan's northern hemisphere, and performed a hot spot and lightning search.
The Composite Infrared Spectrometer (CIRS) continued its search for new species in the far-IR region of the spectrum as well as mapped temperatures in the upper troposphere across the North Polar Region and in the stratosphere around the disk. CIRS also gained the chance to map the distribution of aerosols on the limb in detail.
The Ultraviolet Imaging Spectrograph (UVIS) observed a solar ingress occultation with sampling at mid-southern latitudes near 50 S. The solar occultation was observed with the UVIS EUV channel, which measures H, H2, N, N2 and some hydrocarbons from the exobase. The exobase is the lower boundary of the exosphere, near 3000 km to about 600 km altitude, where molecules or atoms can escape to space just from their thermal velocity because there are not enough atoms or molecules above them to stop them by collisions. For more details on this flyby, go to:
Thursday, June 14 (DOY 165):
Science for the remainder of the week focused on apoapsis approach with ISS observing the outer moons Mundilfari, Tarvos and Kiviuq, and performing long-term temporal monitoring of the F ring, the Cassini Plasma Spectrometer (CAPS) observed dusk-side magnetospheric boundaries at a variety of latitudes, VIMS obtained an edge-on mosaic of the unlit face of the entire ring system near apoapsis and observed the E and G rings near 45 degree phase angles, and UVIS obtained extreme and far UV image scans of Saturn.
A press release on some interesting CAPS and Magnetometer results based on a Nature paper was issued on June 14. The release outlines how Saturn's moons Tethys and Dione are flinging great streams of particles into space. The discovery suggests the possibility of some sort of geological activity, perhaps even volcanic, on these icy worlds.
The full text may be accessed at:
Spacecraft operations hosted an activities review for the S36 sequence today. At these reviews SCO goes over what commands and activities will be needed during the sequence to maintain health and safety and nominal operations for Cassini.
Friday, June 15 (DOY 166):
A member of the Cassini outreach team gave presentations to astronomy and public groups at Grand Canyon, Bryce Canyon, and Death Valley National Parks. Several thousand people attended the talks and eight Saturn viewing opportunities.
In May, the most trafficked part of the Cassini site was the raw image gallery. The most downloaded file in May with over 46,000 downloads was Saturn's Auroras obtained by UVIS.
Several Cassini scientists are to be featured in a new History Channel documentary series, "The Universe," a 13-part series that started on May 29. Each one-hour episode will be devoted to studies of a particular planet or topic. NASA/JPL missions will be featured throughout the series. One full episode will be devoted to Saturn.
The program is scheduled to air every Tuesday at 9 p.m. Eastern through the end of August, with the exception of July 3. The episode focusing on Saturn will show on July 24 with an additional episode on the outer planets on Aug. 14. For more information and the broadcast schedule, visit:
Saturday, June 16 (DOY 167):
Orbit Trim Maneuver (OTM) #116 was performed today. This is the cleanup maneuver for the Titan 32 encounter on June 13. The main engine burn began at 6:00 PM PDT. Telemetry immediately after the maneuver showed the burn duration was 4.59 seconds, giving a delta-V of 0.74 m/s. All subsystems reported nominal performance after the maneuver. With the hydrazine efficient yaw turn rates, 49.4 g of hydrazine were used.
The Navigation team reported that OTM-116 marked the 100th maneuver since launch in October of 1997. The current record holder for a planetary mission is the Galileo mission to Jupiter with 128 maneuvers during the lifetime of the mission. The Cassini flight team looks forward to passing that number some time in 2008.
Monday, June 18 (DOY 169):
The preliminary port for the Science Operations Plan Update process for S34 occurred today. The files are being merged and reports will be sent out shortly. The official port is scheduled for Tuesday, June 26.
The instrument flight software (FSW) normalization process for CIRS began today. The process of normalization involves placing identical copies of the software on all four partitions of the SSR, then performing memory readouts to verify all copies are correct. When an instrument team has a new version of FSW, it is uploaded into two of the partitions. The SSR then contains two copies of the new version and two copies of the old version. The old version is retained until the instrument team performs a checkout and is satisfied that the new version is fully ready for use. Then the new version replaces the old version in the normalization process. Two DSN passes will be required to complete this activity for CIRS so the process will be concluded tomorrow.
Tuesday, June 19 (DOY 170):
The extended mission segmentation working group continued their efforts today by working on some of the issues raised at the recent Project Science Group meeting. The plan is to have the entire extended mission tour divided up into discipline segments by mid August of this year.