Cassini Significant Events 02/03/10 - 02/09/10
The most recent spacecraft telemetry was acquired on Feb. 9 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, Feb. 3 (DOY 034)
In a news release entitled, "NASA Extends Cassini's Tour of
Saturn, Continuing International Cooperation for World Class
Science," NASA announced that the Cassini-Huygens mission has been
extended through 2017.
The project was originally scheduled to end in 2008, but the mission
received a 27-month extension through Sept. 2010 to follow seasonal
changes of an outer planet system from near its northern winter solstice
through its equinox. This second extension, called the Cassini Solstice
Mission, will enable scientists to study seasonal and other long-term
weather changes on the planet and its moons to its northern hemisphere
summer solstice. Cassini arrived just after Saturn's northern winter
solstice, and this extension continues until shortly past northern summer
solstice in May 2017. For the full release link to:
http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20100203/
Port 1 products were due today as part of the S61 Science Operations Plan
(SOP) process. The products will be merged and sent out to the flight
team for review.
There have been no changes to the Preliminary Sequence Integration and
Validation part 2 merge 2, "g" version of S58, currently going
through the final sequence development process. As a result, the sequence
leads were able cancel the final phase of the process. The final approval
meeting is scheduled for Feb. 24 with sequence execution beginning on
Mar. 1.
Thursday, Feb. 4 (DOY 035)
Spacecraft Operations performed a Stellar Reference Unit calibration
on Feb. 4. In addition, the main engine cover was closed as a
precautionary measure for protection against dust hazards on Feb. 13. The
cover will be reopened on Feb. 15.
Each year Cassini scientists pick what they consider to be the top ten
highlights of the year. From the view of the rings at equinox to the
first visible-light images of the northern polar hexagon in almost thirty
years, the scientific bounty continues to grow. For the full descriptions
and images for 2009, link to:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20100203/
Friday, Feb. 5 (DOY 036)
Working with the Deep Space Network, Cassini executed a Radio
Frequency Subsystem (RFS) Static Phase Error (SPE) test over DSS-55. The
purpose was to characterize tracking loop performance by stretching
Static Phase Error. During this test the receiver was locked up and the
uplink frequency was changed by +/- 150 kHz to verify that the tracking
loop is performing nominally.
On DOY 036 a Solid State Power Switch (SSPS) trip occurred, the 29th such
trip since launch. The switch involved controls the Cosmic Dust Analyzer
(CDA) replacement heater. SSPS Fault Protection reset the replacement
heater switch, and then commanded the CDA instrument off, its proper
response. As there was no health and safety concern and critical mission
science was not at risk, plans have been put in place to turn CDA back on
and reset the SSPS trip counter next Tuesday.
Sunday, Feb. 7 (DOY 038)
Along with Composite Infrared Spectrometer (CIRS) and Visual and
Infrared Mapping Spectrometer (VIMS) science observations, the Spacecraft
Operations Office performed a reaction wheel bias, the Magnetometer
performed a downlink roll calibration, and the flight team had an
opportunity for what is called a "Kodak Moment." A Kodak Moment
as the name implies is an opportunity for an aesthetically pleasing image
to be taken. Mission Planning identifies many such opportunities but only
about one per sequence may be implemented, and only if the Navigation
team is able to release an Optical Navigation image placeholder, and only
if margins and workforce allow. For S57 the team was able to obtain a
nice image of Titan, Rhea, the rings, and Saturn to add to the
album.
Monday, Feb. 8 (DOY 039):
An SOP kickoff meeting was held today for S62. The process will run
for approximately 12 weeks and conclude on May 14. The final sequence
development process will begin the following week with execution of S62
beginning on Jul. 30.
This week Imaging Science (ISS), CIRS and the Ultraviolet Imaging
Spectrograph (UVIS) performed observations as part of the Titan
monitoring campaign. UVIS performed mosaic scans of Saturn's
magnetosphere and performed a calibration activity at apoapse to
determine the absolute sensitivity of the extreme and far ultraviolet by
targeting the star Spica. CIRS performed a spectroscopic observation of
an infrared star, measured oxygen compounds in Saturn's stratosphere, and
performed a stray light calibration. Sunlight falling on the CIRS
telescope can be scattered into the instrument by mirror imperfections.
To quantify the effects of ring particle impacts on the mirror
performance, CIRS monitored the scattered IR solar radiation as a
function of the offset angle from the sun.
This month the Cassini Science league brings information on: Negative
Ions, a Positive Sign for Liquid Water in Enceladus. The Cassini plasma
spectrometer, originally designed to take data in Saturn's magnetic
environment, measures the density, flow velocity and temperature of ions
and electrons that enter the instrument. But since the discovery of
Enceladus' water ice plume, the instrument has also successfully captured
and analyzed samples of material in the jets. Now, Cassini scientists
report they have found negatively charged ions in the plume, many of
which are water, but also including other hydrocarbon species. Their
findings, based on analysis from data taken in plume fly-throughs in
2008, are reported in the journal Icarus. Enceladus thus joins Earth,
Titan and comets where negatively charged ions are known to exist in the
solar system. At Earth's surface, negative water ions are present where
liquid water is in motion, such as waterfalls or crashing ocean waves.
For the full text, link to:
http://saturn.jpl.nasa.gov/news/cassiniscienceleague/science20100208/
The Cassini Science League endeavors to share more of the large and
diverse volume of science generated by the scientists on the Cassini
mission. Each Science League entry highlights a science paper or set of
interrelated papers - and provides information on the publication in
which the paper appears. For previous entries link to:
http://saturn.jpl.nasa.gov/news/cassiniscienceleague/
Tuesday, Feb. 9 (DOY 040)
Uplink Operations sent commands to the spacecraft to power on CDA,
return the instrument to normal operations, and to reset the SSPS trip
response counter.
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