Cassini Significant Events 08/11/10 - 08/17/10
The most recent spacecraft telemetry was acquired on Aug. 17 from the
Deep Space Network tracking complex at Canberra, Australia. 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, Aug. 11 (DOY 223)
Beginning today, the first of a series of Command & Data
Subsystem (CDS) flight software V10.0 patches was loaded to the solid
state recorder (SSR) via a real time command spacecraft operations
procedure.
Thursday, Aug. 12 (DOY 224)
A kickoff meeting was held for the S66 Sequence Implementation
Process.
Port 1 for the first set of input files from the teams occurs August
30.
Saturn's moon Titan ripples with mountains, and scientists have been
trying to figure out how they form. The best explanation, it turns out,
is that Titan is shrinking as it cools, wrinkling up the moon's surface
like a raisin. For more information on this subject, link to:
http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20100812/
Friday, Aug. 13 (DOY 225)
The Enceladus 11 (E11) encounter occurred at an altitude of 2,550
kilometers, a speed of 6.8 km/sec, and closest approach at
2010-225T22:29:42.33. The focus of the flyby was the study of thermal
emission from the south polar tiger stripes. Because of the relatively
high altitude, the spacecraft was able to track the moon throughout the
flyby. The Composite Infrared Spectrometer (CIRS) had prime pointing
control during closest-approach. The instrument mapped the thermal
radiation from the tiger stripes, continuing coverage from previous
flybys, and took advantage of the excellent viewing geometry of this
flyby. In particular, CIRS focused on warm transverse fractures that
connect the Alexandria and Cairo Sulci to study whether substantial heat
is escaping from the interior in the regions between the tiger stripes.
To close out this flyby, the Visual and Infrared Mapping Spectrometer
collected compositional data, and then handed over to the Imaging Science
Subsystem (ISS) for further imaging of Enceladus's sister satellite
Tethys. For more information link to:
http://saturn.jpl.nasa.gov/mission/flybys/enceladus20100813/.
Sunday, Aug. 15 (DOY 227)
A test was performed today to determine whether the low-gain antenna
could be used to acquire coherent Doppler data during Titan flybys for
gravity study purposes while the spacecraft is being turned and the
high-gain antenna is off Earth-point supporting acquisition of data by
other instruments. There were three objectives for the test. First was to
determine whether the spacecraft could maintain lock on the uplink
carrier signal at Saturn ranges with the LGA moving and at significant
off-Earth angles. This was the first time for Cassini to attempt two-way
coherent tracking at Saturn ranges using the LGA. Next was to verify that
the statistical noise on the Doppler data using the LGA was sufficiently
small to be scientifically useful, and finally, to verify that the
observed Doppler from the moving LGA could be connected to the
center-of-mass of Cassini with any systematic errors small compared with
the statistical noise. All data were successfully acquired and analysis
is still ongoing, but initial results look favorable.
Monday, Aug. 16 (DOY 228)
Orbit Trim Maneuver 260, the clean up maneuver for the E11 flyby, was
cancelled. The cost of cancellation was only about 10 mm/sec.
Cancellation will require some pointing vectors to be updated, but there
are approximately two weeks to accomplish this activity.
Tuesday, Aug. 17 (DOY 229)
This week's science included a number of observations by the
instrument teams. CIRS observed Dione and then moved on to Enceladus,
where it examined the plume. CIRS also measured the oxygen compounds in
the stratosphere of Saturn for 13 hours. ISS took prime control of the
spacecraft and captured further images of Enceladus's plume, took images
of Dione, and also searched for a Dione plume. ISS performed another
observation in its Satellite Orbit Campaign. The Magnetospheric and
Plasma Science (MAPS) instruments collected data at their nominal survey
rates, and the Magnetometer performed a seven-hour calibration while
rolling about the X-axis of the spacecraft. ISS and CIRS completed
another observation in the Titan monitoring campaign.
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