Status Report

NASA Cassini Significant Events for 08/01/07 – 08/07/07

By SpaceRef Editor
August 11, 2007
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NASA Cassini Significant Events for 08/01/07 – 08/07/07

The most recent spacecraft telemetry was acquired on Tuesday, August 7, from the Madrid 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

Wednesday, August 1 (DOY 213):

An image of the craters on Dione is Astronomy Picture of the Day today. Link to the following to view:

The official port for the S35 Science Operations Plan Update occurred today. The products were merged and the reports delivered to participating teams and to AACS for end-to-end pointing analysis. This process completes and the hand-off to the final S35 sequence development process occurs on Friday, August 17.

An exhibit of “Titan as imaged by Cassini Radar” has been installed in the Division 33 lobby display case in Bldg 238 at JPL. It will be on display from Aug. 1 through Sept. 30. Check it out if you’re at JPL or visiting in the next two months.

The July 28 CHARM telecon, “Saturn’s Rings: the Large and Small” document is now available for download. The PDF versions are on the public Cassini website:

The Target Working Teams (TWT) have begun the sequence integration process for the proposed Cassini extended mission (XM). The Titan Orbiter Science (TOST) and Saturn Orbiter Science Teams (SOST) have already begun this work. During the two-year XM period, sequences will be numbered from S42 through S61, and orbits from 75 to 133. S41 and orbit #74 are the final sequence and orbit of the prime mission. During the month of August the TWTs and OSTs will be working to update the integrated plans for orbits 75 through 78 contained in the S42 sequence. These orbits were actually integrated a couple of years back but need to be updated to the final XM tour geometry. Starting August 27, the Rings TWT will be integrating orbit 79 and part of orbit 80 which are now part of S42. The TWTs and OSTs have a challenging schedule ahead for the XM, especially now during a time when the Cassini Prime Mission sequence development and execution overlaps the development of XM.

Thursday, August 2 (DOY 214):

Cassini scientists may have identified the source of Saturn’s G ring. Gravitational effects from Saturn’s moon Mimas confine relatively large icy particles within a bright arc on the ring’s inner edge. Micrometeoroids collide with the particles, releasing smaller, dust-sized particles that brighten the arc. The plasma in the giant planet’s magnetic field sweeps through this arc continually, dragging out the fine particles, which create the G ring. For the full release on these findings, G ring movies, and images, link to:

Friday, August 3 (DOY 215):

Science this week focused on completion of a series of Saturn movies using the Imaging Science Subsystem (ISS) Wide Angle Camera, Magnetospheric Imaging Instrument (MIMI) imaging of the dynamics of the inner magnetosphere, and the Ultraviolet Imaging Spectrograph (UVIS) performing mosaic mappings of Saturn’s inner magnetosphere in neutral and ionized oxygen emissions.

Saturday, August 4 (DOY 216):

Cassini Science Planning (SP) reported that the Phoenix Mars Lander successfully lifted off this morning at 5:26 a.m. EDT to begin its journey to Mars’ north pole. This is significant for Cassini in that it means the project will be following the 24-hour launch reschedule contingency for adjusted DSN coverage, and will not need to consider implementation of the other contingency plans.

Monday, August 6 (DOY 218):

All teams and offices supported the August Quarterly Review with Cassini and NASA Headquarters personnel attending.

A group of Spacecraft Operations Office Attitude and Articulation Control Subsystem members were presented a NASA New Technology Report award for their report “A Methodology to Determine the Titan Atmosphere Density Using Only Attitude Control Data” in May 2007.

Orbit Trim Maneuver (OTM) #123 scheduled for uplink and execution on Sunday, Aug. 5, was moved to the backup maneuver position today, due to DSN station 14 encountering transmitter difficulties. This will be the first time that Cassini has used the backup pass as a contingency. The only other time a backup pass has been used was for JTM-081 in November of 2006. At that time the backup pass was deliberately selected for use as it avoided a near-singularity condition in the trajectory that occurred near the prime pass. JTM is the designation for an OTM performed over a backup pass.

JTM-123 is the apoapsis maneuver setting up for the Titan 35 encounter on Aug. 31. The main engine burn began at 3:00pm PST. Telemetry immediately after the maneuver showed the burn duration was 2.6 seconds, giving a delta-V of 0.39 m/s. All subsystems reported nominal performance after the maneuver. This is the last maneuver before solar conjunction begins on Aug. 18. The downstream cost of using the backup pass was 70 mm/sec.

Tuesday, August 7 (DOY 219):

Radio Science (RSS) began Solar Conjunction Experiment (SCE) #4 today. For the next four weeks, RSS will characterize the solar corona at two frequency bands, X and Ka1, and assess the electron content and possible Faraday rotation during the solar conjunction period.

Originally scheduled to begin yesterday, but rescheduled due to the one-day delay in execution of OTM-123, Uplink Operations began sending instrument expanded block files to the spacecraft for S33. In addition, a file was sent today to execute on DOY 221 that will compensate for the 24-hour Phoenix launch reschedule. This file could not be sent until after Phoenix had successfully launched. If the file had been sent, and then Phoenix had needed to reschedule again, an incorrect file would have been resident on board Cassini.

S33 was approved today for uplink. The background sequence will begin execution on Saturday, Aug. 11.

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.

SpaceRef staff editor.