NASA Cassini Significant Events 06/17/09 – 06/23/09
The most recent spacecraft telemetry was acquired on June 23 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/mission/presentposition/.
Wednesday, June 17 (DOY 168)
Thanks to an accurate orbit estimation and execution for Orbit Trim Maneuver (OTM) 201, delivery of the spacecraft to Titan for the T57 flyby does not require further modification. Therefore OTM-202 has been cancelled.
Monday, June 22 (DOY 173):
Today begins a week-long series of science meetings and project status reports as part of the 48th Cassini Project Science Group meeting.
The Target Working Team (TWT)/ Orbiter Science Team (OST) integrated products for S56, covering orbits 123 through 125, from December 2009 through January 2010, were delivered today. The integrated products are in their final form and no re-integration is planned. The next step in sequence development, Science Operations Plan (SOP) implementation, will kick off on July 8. Between now and then, the instrument teams will be working on pointing designs for the sequence. TWT/OST teams deliver integrated sequence products for the extended mission about every five weeks.
Today Cassini passed Titan for the T57 flyby with closest approach at approximately 12:52 PM PDT, traveling at 6 km/sec, an altitude of 955 km, and latitude 42.2 degrees S. The Ion and Neutral Mass Spectrometer (INMS) was prime at closest approach with an observation of the night side at mid Southern latitudes. RADAR rode along with INMS using Synthetic Aperture Radar (SAR), outbound altimetry, scatterometry, and radiometry. The SAR runs parallel to tracks from T55 and T56 in the southern hemisphere mapping sequence.
Radio Science (RSS) observed an ingress only occultation, which was a unique opportunity that probed the highest northern latitude ever expected for the Cassini mission, at about 79 degrees North. The measurements will provide a profile of the electron number density of the ionosphere and will help characterize variability in atmospheric conditions such as temperature, pressure, extinction, turbulence, and gravity waves as a function of latitude, in particular in the region of the polar vortex. The characterization is a prime science objective of these Radio Science occultations. This was the last Titan ionospheric and atmospheric occultation in the Cassini Equinox Mission. The experiment completed as planned with all data successfully acquired.
The Composite Infrared Spectrometer (CIRS) conducted mid-southern latitude far and mid infrared vertical composition measurements. Imaging Science had a 0.5-hour illuminated prime observation primarily for photometry, then rode along with the Visual and Infrared Mapping Spectrometer (VIMS) to observe Titan¹s trailing hemisphere at mid-southern latitudes and relatively low phase angle, and with CIRS to monitor clouds. On the inbound leg, the phase angle is much larger than 90 degrees and VIMS ride along observations provided information on Titan¹s atmospheric composition. After closest approach, VIMS observed the south polar region riding along with CIRS.
The Ultraviolet Imaging Spectrograph (UVIS) obtained an image cube of Titan’s atmosphere at extreme and far ultraviolet wavelengths. These cubes provide spectral and spatial information on nitrogen emissions, H emission and absorption, absorption by simple hydrocarbons, and the scattering properties of haze aerosols. This is one of many such cubes gathered over the course of the mission to provide latitude and seasonal coverage of Titan’s middle atmosphere and stratosphere.
The Radio and Plasma Wave Science instrument measured thermal plasmas in Titan’s ionosphere and surrounding environment, searched for lightning in Titan’s atmosphere, and investigated the interaction of Titan with Saturn’s magnetosphere.
