Cassini Significant Events 09/07/11 – 09/13/11

The most recent spacecraft telemetry was acquired on September 13 from the Deep Space Network tracking complex at Canberra, Australia. The Cassini spacecraft is in an excellent state of health and with the exception of one science instrument being powered off, 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/mission/presentposition/.

Wednesday, Sept. 7 (DOY 250)

The S70 sequence began execution today at 2011-250T00:48. The sequence will run for 69 days and conclude on November 15. During that time there will be ten segments; four cross-discipline, four Satellite Orbiter Science Team (SOST), one Titan Orbiter Science Team (TOST) and one Magnetospheric and Plasma Science (MAPS) segment, with four targeted encounters – one Titan (T-78) and three Enceladus (E-14, E-15, and E-16). Also, eleven Orbit Trim Maneuvers (OTMs) are scheduled, numbered 289 through 299.

Friday, Sept. 9 (DOY 252)

This week in science began with the S70 background sequence going active, and included two observations in the Titan monitoring campaign and two sets of astrometric observations of several of Saturn's small inner moons by Imaging Science (ISS). Also, many of the fields-and-particles instruments performed two sets of dedicated measurements of the outer portion of Saturn's magnetosphere. ISS made a 21 hour light curve observation of the outer irregular moon Paaliaq. Leading up to the T-78 flyby, the Composite Infrared Spectrometer (CIRS) made a 12 hour observation of Saturn to measure oxygen compounds in the stratosphere. Following T-78 and approaching periapsis, ISS, CIRS and the Ultraviolet Imaging Spectrograph (UVIS) observed the plume of Enceladus and then the disk of Enceladus from ~42,000 km, and UVIS made measurements of Enceladus' footprint in the auroral region of Saturn.

Saturday, Sept. 10 (DOY 253)

The main engine cover was closed today; performance was normal.

Monday, Sept. 12 (DOY 255)

Cassini encountered Titan (T-78) today at an altitude of 5,821 kilometers and a speed of 5.8 km/sec. The primary observations of the T-78 flyby included CIRS far-IR limb sounding at high latitudes. In addition, UVIS performed a solar occultation experiment, and the visible and infrared mapping spectrometer (VIMS) observed a stellar occultation by Titan's atmosphere of the star R-Aqr. The measurements taken will allow scientists to constrain the composition and the spectral properties of Titan's atmosphere.

The Enceladus/Pallene live Inertial Vector Propagator (IVP) update mini-sequence was uplinked today over Goldstone’s DSS-14 station in support of S70. The mini-sequence is registered and activated on board and will begin execution on 2011-256T08:32:31 SCET.

Port 3 products were due today as part of the S71 Sequence Implementation Process (SIP). The products will be merged and sent out to the flight team for review for both the original sequence with CAPS turned on, and the alternate T-79 flyby sequence to be used in case the CAPS instrument is not turned back on prior to the T-79 flyby.

Tuesday, Sept. 13 (DOY 256)

The Spacecraft Operations Team (SCO) held a meeting today to update the Cassini Plasma Spectrometer (CAPS) personnel on the most recent results from JPL analysis of the Cassini bus voltage imbalance (reference ISA 48671, PFR 49275). Analysis is still on-going, but CAPS remains off for now.

A mission planning forum was held today to discuss operations concepts for the F-ring and proximal orbits. Given the trajectory dispersions and uncertainties predicted for these orbits, concepts such as more frequent live updates, a shorter sequence process, and accepting new orbit determination solutions during the sequencing process were discussed. Feedback on these concepts was requested from all teams. The feedback will be used in establishing the final operations processes to be used for the F-ring and proximal orbits.

Non-targeted flybys of Rhea, Tethys, Pandora, Enceladus, and Janus occurred today.