NASA Cassini Significant Events 07/014/10 - 07/20/10

Status Report From: Jet Propulsion Laboratory
Posted: Sunday, July 25, 2010

image The most recent spacecraft telemetry was acquired on July 20 from the Deep Space Network tracking complex at Canberra, Australia. 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" page at:

Wednesday, July 14 (DOY 195)

The S66 sequence Engineering Activities Review took place today. At this review, Spacecraft Office personnel take a look at all spacecraft activities to be performed during this sequence.

Late in June, a Science representative gave a talk on Cassini to students employed at JPL for the summer. Presentations by people who are enthusiastic about their work and who want to share the experience always make an impression on younger people and this was a big hit. There were smiles on the faces of the audience as they left the auditorium.

Thursday, July 15 (DOY 196)

On July 15, NASA ran an exhibit celebrating "400 years of Discovery from Galileo to the Outer Planets" in the Washington DC Rayburn House Office Building foyer. Missions on display included Cassini, Juno, New Frontiers, and others. The exhibit opened with a panel on Galileo, and a replica of Galileo's telescope. Panels and exhibits shared images from some of NASA's outer planet missions and the ongoing story of their exploration. In addition, Cassini debuted a prototype of "Solar System Explorer," a 3D interactive display using the power of gaming technology coupled with the authenticity of real NASA data that allows the public and students to explore the solar system from their personal computers. For more information on Galileo and his observations of Saturn link to:

Several recent papers by scientists working with Cassini data describe evidence of beaches, sheltered bays, and deltas around Ontario Lacus, the large lake near Titan's south pole. They also describe seasonal changes in the size and depth of the lake. Using data that gives the most detailed picture yet of a lake on another world, scientists and animators have collaborated on a new video tour of Ontario Lacus based on radar data from Cassini's Titan flybys on June 22, 2009, July 8, 2009, and Jan. 12, 2010. A Web-based video has been developed that explains how scientists look to Earth's Death Valley to understand places like Titan's Ontario Lacus. For more information and to view the video, link to:

Friday, July 16 (DOY 197)

Science last week included Composite Infrared Spectrometer (CIRS) measurements of oxygen compounds in Saturn's stratosphere as a function of latitude. In addition CIRS took data for a Saturn mid-infrared map to help determine upper troposphere and tropopause temperatures with spatial resolution of about two degrees of latitude and longitude. Magnetospheric and Plasma Science teams participated in an auroral campaign to observe the auroral magnetosphere in the acceleration region, and Saturn kilometric radiation source regions of Saturn. The Ultraviolet Imaging Spectrograph (UVIS) conducted an extreme ultraviolet / far ultraviolet observation which involved slow scans across the visible hemisphere of Saturn to form spectral images. The Imaging Science Subsystem (ISS) observed small satellites to obtain data for orbit determination. ISS and UVIS took a look at the small irregular moon Kiviuq, and then turned to Titan for cloud monitoring. ISS and the Visual and Infrared Mapping Spectrometer spent time building a Saturn wind speed template by staring and shooting every 10 minutes to create a mosaic in longitude.

Sunday, July 18 (DOY 199)

Orbit Trim Maneuver (OTM) #258 was performed today. This was the apoapsis maneuver setting up for the Enceladus 11 encounter on Aug. 13. The main engine burn began at 12:59 AM PDT. Telemetry immediately after the maneuver showed a burn duration of 39.14 seconds, giving a delta-V of 6.77 m/s, as planned. All subsystems reported nominal performance after the maneuver.

Monday, July 19 (DOY 200)

The Science Forum for S65 was held today. Topics included an overview of science planned for this sequence followed by highlights, unique activities, and highest priority observations as described by the Target Working Team (TWT) and Orbiter Science Team (OST) leads, with comments from the Investigation Scientists and other instrument team representatives.

Seven instrument expanded block files were uplinked to the spacecraft today in support of S62. The remaining files will go up on Tuesday, and the background sequence will follow on Friday. S62 goes active on July 30.

Tuesday, July 20 (DOY 201)

While orbiting Saturn for the last six years, Cassini has kept a close eye on the collisions and disturbances in the rings. This environment provides the only nearby natural laboratory for scientists to see processes that must have occurred in our early solar system as planets and moons coalesced out of disks of debris. Images show icy particles in the F ring clumping into giant snowballs as the moon Prometheus makes multiple swings by the ring. The gravitational pull of the moon moves ring material around, creating wake channels that trigger the formation of objects as large as 20 kilometers in diameter. For more information link to: The DSN track today over Canberra, Australia, started with a Solid State Power Switch (SSPS) trip alarm. Upon investigation, the switch was identified as the one that powers CDS Engineering Unit B. The SSPS trip response algorithm responded by first switching the SSPS OFF, then ON, and the load current has been nominal since then. This is the 32nd in-flight Cassini SSPS trip, about 7 days and 20 hours since the previous trip on the switch that powers the Fields and Particles Pallet backup heater, not breaking the frequency record of 6 days and ~11 hours set by two trips back in February 2000. Commanding will be performed to set and reload the contents of EU-B next week.

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