NASA Cassini Significant Events 02/04/09 – 02/10/09
The most recent spacecraft telemetry was acquired on Feb. 10 from the Deep Space Network tracking complex at Goldstone, California. The Cassini spacecraft is in an excellent state of health. 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.
Thursday, Feb. 5 (DOY 036):
Much of the science data obtained yesterday and today came from Imaging Science’s (ISS) campaign to study the formation of spokes in the rings and to track Saturn’s smallest moons.
A command approval meeting was held today for Instrument Expanded Block (IEB) files for the Composite Infrared Spectrometer (CIRS), Visual and Infrared Mapping Spectrometer (VIMS), ISS, Optical Navigation, Cassini Plasma Spectrometer (CAPS), and Ultraviolet Imaging Spectrograph (UVIS) to be sent to the spacecraft in support of S48. Uplink of these files will begin late in the evening on Feb. 10. S48 begins execution on Feb. 17. In addition to the IEBs, approval was given for uplink of a program to perform maintenance, clear the error logs, repair the CDS library, perform a memory read out, and set the priority playback list.
Friday, Feb. 6 (DOY 037):
The last delivery occurred today for the Science Operations Plan process for S50. On Feb. 20 the files and all related documentation will be bundled up and handed over to Uplink Operations for final sequence development.
Saturday, Feb. 7 (DOY 038):
Cassini completed the targeted Titan 50 flyby on Feb. 7, passing the moon at a distance of 960 kilometers above the surface, and at a speed of 6.3 km/s. Closest approach occurred at about 2:06 AM PST at a latitude of 33.7 degrees S.
TITAN-50 Science Highlights
Closest approach at T50 featured the Ion and Neutral Mass Spectrometer (INMS) as the “prime” instrument, in control of exactly where the spacecraft would be pointed for this flyby. The observation was designed to measure the boundary between the wake side and the inner flank of the magnetospheric interaction region at mid-southern latitudes. RADAR rode along with INMS at closest approach. During the flyby, the instrument collected synthetic aperture radar data over the mountain ranges southwest of Tsegihi, and obtained altimetry measurements inbound and outbound.
For the Optical Remote Sensing instruments, CIRS focused on mapping temperatures, trace hydrocarbons, nitriles and oxygen compounds in Titan’s stratosphere along with searching for weak isotopes and new gas species. VIMS performed cloud mapping and observations of the atmosphere at the limb. UVIS obtained an image cube of Titan’s atmosphere at extreme ultraviolet and far ultraviolet wavelengths by sweeping its slit across the disk. 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.
For the Magnetosphere and Plasma Science suite of instruments, the Magnetospheric Imaging Instrument (MIMI) measured energetic ion and electron energy input to Titan’s atmosphere. Because T50 was an upstream flank-in flyby, the geometry was suitable for the Magnetometer Subsystem (MAG) to study the magnetic pileup region across the night side hemisphere. T50 also took place in Saturn’s near-noon sector where Titan could be found in the magnetosheath if the solar wind pressure was high. This is an arrangement that is also of interest to MAG. Finally, 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.
Monday, Feb. 9 (DOY 040):
Orbit Trim Maneuver (OTM) #182 was performed today. This is the cleanup maneuver from the Titan 50 encounter on Feb. 7. The main engine burn began at 3:15 AM PST. Telemetry immediately after the maneuver showed the burn duration was 2.1 seconds, giving a delta-V of 0.35 m/s. All subsystems reported nominal performance after the maneuver.
Tuesday, Feb. 10 (DOY 041):
A kickoff meeting was held yesterday for a live update for Saturn and Titan to occur over DOY 44-45. By today, all the votes were in. With no pointing errors above 0.43 mrad, the changes would be well below the threshold necessary to drive this update process. With the concurrence of Science Planning and all participating instruments, the update has been cancelled.
