Cassini Update - December 18, 2009
baa...@earthlink.net
for 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:
http://saturn.jpl.nasa.gov/video/videodetails/?videoID=200
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 Saturn's
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:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20091210/
and
http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=3772
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:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20091211/
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:
http://saturn.jpl.nasa.gov/news/cassiniscienceleague/science20091214/
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.
Visit the JPL Cassini home page for more information about the
Cassini Project:
http://saturn.jpl.nasa.gov/>
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