Status Report

NASA Cassini Significant Events for 08/18/05 – 08/24/05

By SpaceRef Editor
August 28, 2005
Filed under , , ,
NASA Cassini Significant Events for 08/18/05 – 08/24/05

The most recent spacecraft telemetry was acquired Wednesday, August 24, from the Goldstone tracking 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 .

Thursday, August 18 (DOY 230):

A sponge bit meeting was held today as part of S15 sequence development. Sponge bits represent available data volume that is given away to the science teams during the first cycle of preliminary sequence development in the Science and Sequence Update Process (SSUP). No further changes are expected to DSN allocations, so much of the data volume that was being held as margin is given to the teams for science. Prior to the meeting, the Science Planning lead determines how much extra data volume is available and teams request data volume that they need. If more data volume is requested than is available, negotiations are made during the meeting.

Friday, August 19 (DOY 231):

Just prior to periapsis, which will occur tomorrow at 232T11:15, the Composite and Infrared Spectrometer (CIRS) along with the Imaging Science Subsystem (ISS) and the Ultraviolet Imaging Spectrograph (UVIS) tracked cloud and storm features across the face of Saturn. Slow scans with the infrared detectors were used to determine tropospheric thermal structure at high spatial resolution. Temperature anomalies will be correlated with motions and features in images taken by ISS.

A talk was given at noon today in Von Karman Auditorium entitled “26Al in Iapetus – Consequences for the Formation and Evolution of the Saturnian System.” This seminar was about the dynamics and shape of Iapetus, a distant satellite of Saturn, and how it turns out to yield crucial clues for unveiling the history of the Saturnian nebulae and the Solar System. With its short half-life, 26Al has been used as a fine-scale chronometer to date events occurring in the early history of the Solar System. Iapetus is the first case among planetary satellites where other models cannot suffice and heat from Calcium-Aluminum Inclusions (CAI) is absolutely required. This allows us to date the age of Iapetus as 4.565 8 ± 0.000 6 Gy. This sets a lower bound on the age of Saturn, the upper bound being the age of the CAIs. This result has important consequences for our understanding of the Saturnian system and provides new constraints for models for the formation of the outer Solar System. Implications for the geology of Iapetus and the other Saturnian satellites was also discussed.

A test of the Titan-7 flyby sequence was successfully performed in the Integrated Test Laboratory (ITL) using the new 050720 reference trajectory, incorporating the higher T-7 flyby altitude. The T-7 flyby will occur on September 7.

The Main Engine cover was fully deployed or “closed” this morning. Telemetry values are consistent with a nominal deployment. The deployment telemetry data will be queried for subsequent analysis and sent to JPL Division 35 personnel for modeling and tracking the use of this hardware.

The official delivery port occurred as part of the Science Operations Plan Update process for S16. The merged products are currently being run through the end-to-end pointing validation process by ACS. A Project Briefing and Waiver Disposition Meeting is scheduled for August 31.

Saturday, August 20 (DOY 232):

Non-targeted Flybys occurred today of Tethys at 122,750 km and Telesto at 105,340 km.

Sunday, August 21 (DOY 233):

Six of the eight scheduled Ion and Neutral Mass Spectrometer (INMS) SSR Instrument Expanded Block (IEB) loads for S14 were uplinked today. Normally these IEBs would have gone up later in the week along with the other instrument IEBs and background sequence. The files were sent up early due to a scheduling conflict with uplink of OTM-029 and the resulting shortened uplink window. The remaining IEB files and background sequence will be sent up beginning on Friday August 28.

The S14 DOY 248 live update schedule for the Pandora/Titan Inertial Vector Propagator (IVP) update and the Radio Science (RSS) DOY 250 Saturn occultation Live Movable Block was sent out to the S14 distribution list. The kickoff meeting for this process is scheduled for Monday August 29.

The four Sequence Change Requests (SCR) approved at the S14 final SCR/waiver approval meeting earlier this week were incorporated into the “g” version of the background sequence. The sequence products were then published to the program file repository, and the sequence of events, space flight operations schedule, and DSN keywords files will be published tomorrow. The RSS Live Movable block remained at its PSIV2 “b” version since no changes were needed in the final sequence development phase.

Monday, August 22 (DOY 234):

The T6 flyby of Titan today was outbound with a closest distance of 3660 km at 08:54 GMT. This is one of the few flybys of Titan with opportunities for far-infrared limb sounding by CIRS both inbound and outbound. Unlike nadir measurements that intercept the surface, limb sounding allows the instrument to measure temperatures in the lower stratosphere region. The temperature data, along with pressure and aerosol measurements, was collected near 55 degrees south latitude.

For the Dual Technique Magnetometer (MAG), this flyby was an opportunity to study an exotic dayside wake/tail region. During T6, the upstream side of magnetospheric flow relative to Titan was also the night side. These conditions may allow the frozen-in magnetic field to convect through the night side ionosphere and interact with Titan’s interior afterwards.

Additional science activities for this encounter included the acquisition by ISS of high-resolution images also at high southern latitudes south of Xanadu. UVIS, riding on the CIRS observations, performed spectroscopy for constituent identification, and the Cosmic Dust Analyzer continued to map dust densities and dust dynamical properties within Titan’s orbit.

At closest approach, the Optical Remote Sensing instruments scanned across the South Pole conducting the first detailed investigation of the southern polar region, an area noted for cloud formation and evolution and possibly even a lake.

Tuesday, August 23 (DOY 235):

An Encounter Strategy Meeting for Titan-6 and Titan-7 was held today. This will cover Orbit Trim Maneuvers 29-31, and a period from the T6 flyby on August 22, to the T7 flyby on September 7.

Signatures have been obtained for all three RADAR archive Software Interface Specification (SIS) documents. At this time, all outstanding archive SISs have been approved. This marks a formal transition of the Archiving task from development to operations. The initial delivery of data products was on July 1, with future deliveries scheduled every three months.

Wednesday, August 24 (DOY 236)

A Cassini picture of Epimetheus, a small moon of Saturn, was selected as Astronomy Picture of the Day today. A query on the APOD website yielded over 100 images from Cassini.

Members of the Spacecraft Operations Office (SCO) have placed files for OTM-29 in the program file repository. As of today, Navigation has delivered the final maneuver solution, ACS has begun Flight Software Development System testing, the sequence leads have merged the maneuver files with the background sequence, and all SCO subsystems have begin their checklists on the merged products. OTM-29 is scheduled to be uplinked to the spacecraft and executed on Thursday, August 25.

The final sequence approval meeting for S14 was held today. Uplink of sequence products will continue as scheduled on Friday.

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.