From: Jet Propulsion Laboratory
Posted: Sunday, October 12, 2008
The most recent spacecraft telemetry was acquired on Oct. 7 from the Deep Space Network tracking complex at Goldstone, California. 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: http://saturn.jpl.nasa.gov/operations/present-position.cfm.
Wednesday, Oct. 1 (DOY 275):
The Cassini-Huygens Analysis and Results of the Mission (CHARM) teleconference for September was held last week. The topic: Cassini Composite Infrared Spectrometer (CIRS): Instrument, Operations, and Science.
The Science Operations Plan kickoff meeting for the S49 sequence was held today. Files to be delivered for the first port are due Oct. 23.
Thursday, Oct. 2 (DOY 276):
A non-targeted flyby of Tethys occurred today.
Orbit Trim Maneuver (OTM) #165 was performed today. This is the periapsis maneuver setting up for the Enceladus 5 encounter on Oct. 9. The main engine burn began at 4:44 AM PDT. Telemetry immediately after the maneuver showed the burn duration was 23.71 seconds, giving a delta-V of 3.93 m/s. All subsystems reported nominal performance after the maneuver.
The main engine cover was closed today at end of the OTM-165 prime window for a dust hazard. It was reopened about 2.5 hours later. This was cycle #46 for the cover.
Heading into Saturn periapsis, activity on-board the spacecraft has increased. The day began with a short high resolution F ring stare by the narrow angle camera. Meanwhile, the Magnetospheric and Plasma Science (MAPS) teams collected data at increased rates. Of particular note, the Radio and Plasma Wave Science (RPWS) instrument performed a "whistler" activity. Whistler observations are used to obtain wideband evidence of lightning whistlers which would verify the existence of lightning already suspected from Saturn Electrostatic Discharges (SED) and provide information on the electron density along the field line to the source. After this, the spacecraft turned to Earth to downlink the data and clear the SSRs in preparation for receipt of periapsis data. The downlink was interrupted briefly for OTM-165, the final deterministic maneuver before Enceladus 5.
Following the downlink, MAPS had prime pointing to observe the auroral magnetosphere and Saturn Kilometric Radiation source region. MAPS and Optical Remote Sensing (ORS) teams coordinated the pointing and timing closely so that CIRS could observe Tethys as it was eclipsed by Saturn. Finally, the last short activity of periapsis science was a joint Ultraviolet Imaging Spectrograph (UVIS), Visual and Infrared Mapping Spectrometer (VIMS), Imaging Science Subsystem (ISS), and CIRS campaign to study the auroras at Saturn's poles.
Friday, Oct. 3 (DOY 277):
A non-targeted flyby of Titan occurred today.
The spacecraft was busy executing many short duration activities. The first was ISS with another observation set in the campaign for small satellite orbit determination. Next, the Cassini Plasma Spectrometer (CAPS) took pointing control of the spacecraft for MAPS instruments to collect enhanced survey data. After CAPS, the spacecraft turned towards Earth to downlink science data. During the downlink, Radio Science (RSS) performed an Operational Readiness Test to demonstrate DSN and RSS preparedness to support the orbit 89 rings occultation experiment on DOY 291. Following the downlink, CIRS took a thermal scan of the rings. VIMS had the next activity, again observing a stellar-ring occultation, this time of the outer A-ring region. Afterwards, the full suite of ORS instruments observed Mimas to collect additional longitudinal and phase angle coverage. The day concluded with ISS taking another series of small satellite orbital determination images plus one Titan cloud monitoring image.
Monday, Oct. 6 (DOY 280):
Orbit Trim Maneuver (OTM) #166 was performed today. This is the approach maneuver setting up for the Enceladus 5 encounter on Oct. 9. The reaction control subsystem burn began at 12:29 PM PDT. Telemetry immediately after the maneuver showed the burn duration was 8.13 seconds, giving a delta-V of 14.96 mm/s. All subsystems reported nominal performance after the maneuver.
The Oct. 9 flyby of Enceladus is the first of two to occur in October. This is the closest flyby yet of any moon of Saturn, at only 25 kilometers from the surface. The Oct. 31 flyby is farther out, at 196 kilometers. During the Oct. 9 flyby, the on-board fields and particles instruments will venture deeper into the plume than ever before, directly sampling the particles and gases. The emphasis here is on the composition of the plumes rather than imaging the surface. On Oct. 31, the cameras and other optical remote sensing instruments will be front and center, imaging the fractures that slash across the moon's south polar region. For more information link to: http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=874
The NASA blog is active once again for the E5 flyby on Oct. 9. To participate, link to: http://blogs.nasa.gov/cm/blog/enceladus
Closest approach will occur on Oct. 9 at 1:30 PM Pacific Time. Just 29 seconds after closest approach, Cassini will fly directly over the South Pole at an altitude of 339 kilometers. The first data will hit the ground at about 2:30AM Pacific Time on Oct. 10.
Tuesday, Oct. 7 (DOY 281):
The main engine cover was closed today at the end of the OTM-166 backup window for a potential dust hazard as part of the Enceladus 5 flyby on Oct. 9. It will be opened after the flyby on Oct. 10. This will be cycle #47 for the cover. Spacecraft Operations (SCO) hosted the S50 Engineering Activities Review today. The objective of the meeting is for SCO and Navigation to take a long look ahead - S50 executes in May of 2009 - and determine whether there are any periods or activities where contingency planning might be appropriate.
As part of the sequence development process for S46, the RADAR team requested that their designs for the Titan T48 and T49 flybys be simulated in the ITL. The simulations will begin today and continue through the weekend.
// end //