Cassini Update - September 19, 2008
- From: baalke@xxxxxxxxxxxxx
- Date: Fri, 19 Sep 2008 15:08:46 -0700 (PDT)
Cassini Significant Events
for 09/10/08 - 09/16/08
The most recent spacecraft telemetry was acquired on Sept. 16 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/operations/present-position.cfm.
Wednesday, Sept. 10 (DOY 254):
Science activities today began with the Cassini Plasma Spectrometer
(CAPS) leading a Magnetospheric and Plasma Science (MAPS) auroral
investigation. After turning to Earth and downlinking this data, the
spacecraft stayed Earth pointed as the rings of Saturn passed between
Earth and the spacecraft. This provided an opportunity for a Radio
Science (RSS) ring occultation experiment. Cassini used its radio
transmitter to send multiple frequency radio signals through the
rings. Scientists carefully monitor the signals as they are received
on Earth. This allows them to deduce the structure and composition
of the rings. The day ended with a joint Optical Remote Sensing
(ORS) campaign of Saturn's south polar region.
A non-targeted flyby of Epimetheus occurred today.
Science Planning, Composite Infrared Spectrometer (CIRS), Imaging
Science (ISS), Ultraviolet Imaging Spectrograph (UVIS), and Visual
and Infrared Mapping Spectrometer (VIMS) teams weighed in today at
the Go/No Go meeting for the first S44 Live IVP Update. It's a go
for updates to Saturn, Cassini, and Enceladus vectors to execute on
DOY 161. Uplink of the necessary files is planned for next Monday.
The Cassini Radio Science (RSS) S43 orbit 84 rings chord occultation
was completed on Wednesday, Sept. 10. The experiment was covered by
Madrid's DSS-63 station with X- and S-band support, and DSS-54 with
X- and Ka-band support. This was the last in a family of four fast
chord occultations that probed the rings when the opening angle was
small, about 5 to 7 degrees. This was also the first time DSS-54
provided RSS occultation experiment support. DSS-55 at Madrid is
usually scheduled to support the RSS Ka-band activities, but since
that antenna is currently down for upgrades and maintenance, DSS-54
was scheduled instead.
A nice image of the Anthe ring arc around Saturn was Astronomy
Picture of the Day today. The image may be seen at:
http://antwrp.gsfc.nasa.gov/apod/ap080910.html
Thursday, Sept. 11 (DOY 255):
Sequence Team leads uplinked the S44 background sequence today. In
addition, a CIRS noise test and flight software patches to instrument
FSW version 5.0.4 were also uplinked. The patches will be used to
determine the best way to remove certain types of noise from the CIRS
science data. Following the results of the noise tests, a permanent
patch to the CIRS FSW will be made. The permanent patch will decrease
the odds of the CIRS scan mechanism becoming stuck by increasing a
timing constraint the software uses in controlling the
mechanism. The current CIRS commands will execute on DOY 259.
Saturday, Sept. 13 (DOY 257):
Science activities at the end of S43 included a continuation of an
orbit determination study performed by ISS on some of the
lesser-known Saturnian satellites. Next, UVIS, CIRS, and ISS
observed Saturn's moon Rhea for six and a half hours to look for
trace volatile elements. This was followed by ISS images of the
G-Ring arc and an opportunistic "mutual event" image of Dione
transiting across Enceladus. Finally, CAPS led another MAPS survey
of the magnetic and plasma environment of Saturn.
The S43 sequence concluded and S44 began execution today at
2008-257T23:44 SCET. The sequence will run for 35 days and conclude
on Oct. 18. During that time there will be a targeted encounter of
Enceladus and fifteen non-targeted flybys - two each of Titan,
Tethys, and Pallene, and one each of Pandora, Mimas, Calypso,
Daphnis, Atlas, Pan, Telesto, Janus, and Epimetheus. Five maneuvers
are scheduled, numbered 164A, and 165 through 168,
Monday, Sept. 15 (DOY 259):
A presentation on "Missing Noble Gases from the Titan Atmosphere"
was given today at JPL. The noble gases are a group of chemical
elements with very similar properties; under standard conditions,
they are all odorless, colorless, monatomic gases, with a very low
chemical reactivity. The six noble gases that occur naturally are
helium, neon, argon, krypton, xenon, and the radioactive radon. The
melting and boiling points for each noble gas are close together,
differing by less than 10 degrees Celsius; consequently, they are
liquids only over a small temperature range.
Sequence leads sent commands to the spacecraft today for a Cosmic
Dust Analyzer (CDA) ring plane crossing activity and a noise test,
and for the S44 Live Inertial Vector Propagator (IVP) Update #1. All
files have properly registered on-board the spacecraft.
Tuesday, Sept. 16 (DOY 260):
A non-targeted flyby of Titan occurred today.
The S46 Science Operations Plan product was handed off to the
Sequence Team today and the final sequence development process for
S46, the Science and Sequence Update Process, began. Items still to
be closed are RADAR requests for testing of the T48 and T49 Titan
flybys in the Integrated Test Laboratory, and establishing a schedule
and resources for the three Live IVP updates scheduled in S46.
Today a talk was presented on "Saturn's moon Titan: View from
Cassini's RADAR Mapper." Case studies using Synthetic Aperture Radar
(SAR) and high-resolution radiometry data for geological mapping and
characterization of Titan's surface were presented. Emphasis was on
flows and drainage patterns, geology, crater structures, dunes,
lakes, and evidence of structural control on drainage and flow
features in the Hotei area. Suggestions were also presented on
opportunities for data synergy between SAR/high-resolution
radiometry/VIMS for geological mapping and SAR/altimetry/VIMS for
surface and subsurface studies.
Visit the JPL Cassini home page for more information about the
Cassini Project: <http://saturn.jpl.nasa.gov/>
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