News | June 13, 2012
Cassini Significant Events 06/06/2012 - 06/12/2012
The most recent spacecraft tracking and telemetry data were collected on June 13 by the Deep Space Network's 70 meter Station 43 at Canberra, Australia. Aside from the Cassini Plasma Spectrometer Subsystem (CAPS), which is off, and the Ultrastable Oscillator (see the Jan. 5, 2012 Significant Events), the Cassini spacecraft is in an excellent state of health with all its subsystems 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's targeted Titan encounter, T84, was this week's highlight. The 959 kilometer flyby of Saturn's largest satellite increased Cassini's orbital inclination from 15.8 to 21.1 degrees with respect to Saturn's equatorial plane, and increased the orbit period from 16 to 24.9 days. More information may be found on the T84 page here:
On Saturday and again on Monday, the Imaging Science Subsystem (ISS) performed observations in the Satellite Orbit Campaign, looking near Saturn where small satellites ("rocks") may be found, seeking to improve knowledge of their orbits or make new discoveries.
Wednesday, June 6 (DOY 158)
Inbound to Titan, the Composite Infrared Spectrometer (CIRS) observed vertical profiles of atmospheric temperatures and the presence and abundance of trace gasses. The Visible and Infrared Mapping Spectrometer (VIMS) acquired data to monitor climatic changes, and to look for specular reflection of the Sun on northern lakes. A previously acquired VIMS image illustrates the latter concept here:
For closest approach, attitude control was commanded to switch from reaction wheels to thrusters to provide increased control authority over atmosphere-generated torques. The maximum duty cycle was about 29%, less than predicted and indicating a less dense atmosphere than expected.
The Radar instrument acquired high-resolution Synthetic Aperture Radar (SAR) imaging around closest approach, and altimetry and lower-resolution SAR imaging from higher altitudes. Information on these Radar techniques may be found here:
The Radio and Plasma Wave Science instrument (RPWS) measured thermal plasmas in Titan's ionosphere and surrounding environment, searched for lightning in Titan's atmosphere, and investigated Titan's interaction with Saturn's magnetosphere.
The Magnetospheric Imaging Instrument (MIMI) measured the energetic ion and electron energy input to Titan's atmosphere.
Attitude and Articulation Control Subsystem Flight Software version A8.9.0 was approved at a Project Change Control Board meeting. The new software will be installed on the spacecraft in December.
Thursday, June 7 (DOY 159)
Outbound from Titan, the Ultraviolet Imaging Spectrograph (UVIS) obtained an image cube of Titan's atmosphere at extreme- and far-ultraviolet wavelengths by sweeping its slit across the disk. ISS rode along (took advantage of spacecraft pointing) and acquired low-phase-angle observations of Adiri and the region where extensive surface changes were observed in Fall 2010.
Friday, June 08 (DOY 160)
The 70 meter diameter Deep Space Network (DSN) stations in California and Spain successfully captured all the telemetry data that Cassini played back from the T84 encounter.
ISS monitored Titan to track clouds and their evolution for an extra day after T84. CIRS and VIMS rode along with ISS to monitor seasonal change. Radar performed a radiometry calibration.
The Instrument Expanded Block commands to support the S74 sequence were uplinked yesterday and today. All 10,777 commands from nine files were confirmed aboard the spacecraft.
Saturday, June 09 (DOY 161)
CIRS observed Saturn for 12 hours to measure oxygen compounds (H2O, CO2) in the stratosphere. The Navigation team took five images of the small satellite Mimas for Optical Navigation.
Sunday, June 10 (DOY 162)
Orbit Trim Maneuver 326, the T84 cleanup maneuver, was performed using the main engine. The 2.4 second burn provided a delta-V of 420 millimeters per second.
CDA performed a 12.5 hour interstellar dust observation.
Two dozen Cassini flight team members participated in this year's Open House at JPL, which drew record crowds.
Monday, June 11 (DOY 163)
ISS, CIRS, and VIMS performed another observation in the Titan monitoring campaign, then CIRS began a 33.5 hour mid-infrared map of Saturn to determine upper troposphere and tropopause temperature.
The S74 command sequence was approved today for uplink Thursday night.
Tuesday, June 12 (DOY 164)
The DSN telemetry processing issue that introduced packet timing error flags has been fixed. Ground data processing for ISS and VIMS products is back to normal.