News | December 16, 2009
Cassini Significant Events 12/09/09 - 12/15/09
The most recent spacecraft telemetry was acquired on Dec. 15 from the Deep Space Network tracking complex at Madrid, Spain. 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, Dec. 9 (DOY 343)
A non-targeted flyby of Helene occurred today.
A three-frame animation and a still image of the mysterious hexagon surrounding Saturn's north pole were released today. They are the first visible light images yet from Cassini of this structure. For images and text link to:
In addition to the data collected at the Titan 63 flyby this week, the Composite Infrared Spectrometer (CIRS) measured helium abundance at the Radio Science (RSS) egress occultation point. The Cosmic Dust Analyzer (CDA) was observing during the ring plane crossing. RSS performed a radio occultation of Saturn's ionosphere and atmosphere to measure vertical profiles of electron density in the ionosphere, and of density, pressure, and temperature in the neutral atmosphere. The Magnetospheric and Plasma Science (MAPS) instrument teams conducted a satellites and rings interactions campaign to observe the interaction between the magnetospheric hot ions and electrons, rings, and icy satellites, and observed the dawn-side magnetospheric boundaries at a variety of radial distances. The Visual and Infrared Mapping Spectrometer (VIMS) observed the E and G rings at 80 degree phase, and the Ultraviolet Imaging Spectrograph (UVIS) performed a 12-hour Saturn system scan to observe atomic oxygen and hydrogen.
Thursday, Dec. 10 (DOY 344)
A non-targeted flyby of Pallene occurred today.
The main engine cover was closed on Dec. 9 at the end of the OTM-226 backup maneuver pass, and will be reopened tomorrow. This is the 54th in-flight cycle.
A news note entitled "Reddish Dust and Ice Migration Darken Saturn¹s Moon Iapetus" described new papers and images that explain how the moon's bizarre, yin-yang-patterned surface came to be. The papers appeared online in the journal Science on Dec. 10. To view the article and images link to:
Files containing commands to return the command loss timer value to 90 hours, and a CIRS DOY 350 ZPD position test were uplinked to the spacecraft today. Timed to execute on DOY 350, the commands were designed to patch CIRS flight software and collect science data to report min and max data positions to investigate the feasibility of improving the ZPD position calculation. At the end of the test, the flight software was patched back to the current version.
Friday, Dec. 11 (DOY 345)
A news note entitled, "Magnetic Dance of Saturn and Titan to Be Main Attraction during Upcoming Flyby," previewed the Dec. 12 targeted flyby of Titan. The note indicated that Cassini planned to study the interactions between the magnetic field of Saturn and Titan. For the full text link to:
Today Cassini flew by Titan at an altitude of 4,850 km and a speed of 6 km/sec. Closest approach for T63 occurred at 07:23 PM PST on Dec. 11 (Dec. 12 GMT), latitude 33 degrees N. Occurring near dusk in Saturn's magnetosphere, this was the Equinox mission's most opportune passage through the wake that Titan creates as it plows through Saturn's magnetosphere. With the Cassini Plasma Spectrometer (CAPS) leading the pointing at closest approach, this flyby was similar and very complementary to the Voyager - November 1980 and August 1981- and Cassini Titan 9 - December 2005 - encounters of Titan, and was the second of three opportunities for a CAPS Equinox Mission prime encounter. The flyby was also designed to set up the correct orientation for the first ansa-to-ansa ring occultation.
ADDITIONAL TITAN-63 SCIENCE HIGHLIGHTS
RADAR: Performed radiometry on the inbound leg of the flyby.
ISS: Acquired regional- and global-mapping mosaics of northern Adiri and rode along with VIMS and CIRS to monitor clouds. ISS also monitored Titan to track clouds and their evolution for an extra day after the Titan encounter.
VIMS: Monitored the cloud cover during the inbound period. After closest approach, VIMS rode along with ISS to acquire a mosaic of Shangri-La and Belet at a resolution of 40 km per pixel. VIMS also acquired a global map for cloud monitoring.
CIRS: Carried out far-infrared limb sounding at 70 and 75 degrees south latitude to collect information on atmospheric temperature, aerosols and composition, and observed stratospheric composition and temperature.
MAG: Obtained information about the pitch angle distribution of Titan's escaping plasma. This flyby increased our understanding of the properties of Titan's mid-range tail region, further extending observations made during T9.
MIMI: Observed energetic ion and electron energy input to the atmosphere.
RPWS: 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
UVIS: Obtained an image cube of Titan's atmosphere at extreme ultraviolet 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.
For additional information, link to:
http://saturn.jpl.nasa.gov/mission/flybys/titan20091212/ and http://saturn.jpl.nasa.gov/files/20091212_titan_mission_description.pdf
Monday, Dec. 14 (DOY 348):
A view of Saturn's north pole was Astronomy Picture of the Day today. Check it out at: http://antwrp.gsfc.nasa.gov/apod/ap091214.html
Other than Enceladus, there are very few known active moons in the solar system. These rare worlds provide a window on the processes that shape different planetary environments. In a second Cassini Science league release for December, scientists discuss searching for activity on Saturn's mid-size moons. For the full release link to:
Tuesday, Dec. 15 (DOY 349)
Orbit Trim Maneuver (OTM) #227 was performed today. This was the cleanup maneuver from the Titan 63 encounter on Dec. 11. The main engine burn began at 12:14 AM PST. Telemetry immediately after the maneuver showed a burn duration of 4.18 seconds, giving a delta-V of 0.713 m/s. All subsystems reported nominal performance after the maneuver.
Uplink of the S56 Instrument Expanded Block files began today. The background sequence will go up Friday, Dec. 18, and S56 will begin execution on Dec. 22.
All participating teams delivered files today for the first input port of the S60 Science Operations Plan process.
The Target Working Team (TWT)/ Orbiter Science Team (OST) integrated products for S61, covering orbits 133 through 135 in June and July, 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 Jan. 13. The handoff package template from integration to the SOP process has been updated to better track more involved prime-rider pointing designs, and the two new milestones added to the S60 schedule for prime-rider coordination have been moved closer to port 1 for S61. Between now and the kickoff, the instrument teams will be working on pointing designs for the sequence.