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Posted by baalke on November 13, 2007, 5:54 pm
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Cassini Significant Events
for 10/31/07 - 11/06/07
The most recent spacecraft telemetry was acquired on Tuesday, November
6,
from the Madrid tracking complex. 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" web page located at
http://saturn.jpl.nasa.gov/operations/present-position.cfm.
Wednesday, October 31 (DOY 304):
The S39 Aftermarket process completed today. The Science Operations
Plan
Update process for this sequence will kick off on Wednesday, Nov. 7.
Submodule 39 on SSR-A was turned off October 31, 2007. This submodule
failed in December, 2006, and has been causing some minimal level of
data
corruption since then. The ability to isolate faulty memory
submodules in
the SSR is a new capability available in the CDS V10 flight software
that
was installed on the spacecraft in October.
The S35 background sequence began execution today. The sequence will
run
for 44 days, concluding on Dec. 14. During that time there will be
two
targeted flybys of Titan, T37 and T38, eight non-targeted encounters,
one
each of Rhea, Pandora, Pan, Calypso, Telesto, and Mimas, two of
Epimetheus,
and orbit trim maneuvers numbered 132-138.
The S35 sequence began execution while the spacecraft was upstream of
Saturn's bow shock. To take advantage of this, the Magnetospheric and
Plasma Science (MAPS) instruments began a 63-hour campaign to monitor
solar
wind conditions in the vicinity of Saturn. At the same time the
Cosmic Dust
Analyzer (CDA) measured the properties of dust outside the Saturnian
magnetosphere. Later in the day Imaging Science performed a one-hour
observation of the F ring as part of long term temporal monitoring of
this
ring.
Last week Cassini Outreach participated in the Mt. Wilson Girl Scout
Council's Family Science Festival held at Monrovia High School on
Sunday,
Oct. 28. Around 1,100 people from Brownies to Seniors to parents to
troop
members rotated through several dozen demonstrations, activities, and
talks
about science.
Thursday, November 1 (DOY 305):
Orbit Trim Maneuver (OTM) #132 was performed today. This is the
apoapsis
maneuver setting up for the Titan 37 encounter on Nov. 18. The main
engine
burn began at 10:00 AM PDT. Telemetry immediately after the maneuver
showed
the burn duration was 6.01 seconds, giving a delta-V of 0.967 m/s, as
planned. All subsystems reported nominal performance after the
maneuver.
Friday, November 2 (DOY 306):
Cassini spacecraft personnel participated in a meeting today with Div.
35
engineers to discuss main engine (ME) cover cycles. The current in-
flight
limit for this consumable is 37 cycles. To date, 35 of the 37 have
been
used. Completing the prime mission with the current cover use policy
will
require approximately 40 cycles and the proposed Extended Mission will
add
about 22 more cycles. Cover performance has been nominal, the risk of
continued cover use is believed to be low compared to the risk of dust
hazards without the cover, and a cover anomaly contingency plan is in
place.
It was decided to waive the limit, continue using the cover on an as-
needed
basis, and carefully monitor its performance.
The Titan Orbiter Science Team held an integration meeting today to
complete
the high-level integration for all of the Titan flybys in the proposed
Extended Mission (XM). The Satellite Orbiter Science Team will be
holding a
similar integration meeting on November 16 to integrate the Enceladus
flybys
in the XM.
As part of the normal development process for S36, it was determined
that
Radio Science and RADAR would like to perform a test in the Integrated
Test
Laboratory (ITL) for the Titan 39 flyby on Dec. 20. The test began
today
and will conclude on Nov. 7.
Sunday, November 4 (DOY 308)
On DOY 308, Radio Science (RSS) performed a unique radio-science-in-
reverse
demonstration. During normal Radio Science experiments that are based
on a
one-way radio signal, the downlink signal from the spacecraft is
monitored
as the spacecraft passes behind some target of interest - Saturn's
rings,
the atmosphere of Titan, or the atmosphere of Saturn itself - as
viewed from
Earth. In this experiment, an S-band signal at 2040 MHz was
transmitted from
DSS-24 and received on-board the Cassini spacecraft by the European
Space
Agency's Probe Support Avionics (PSA). These are the same receivers
that
were used to communicate with the Huygens Probe as it descended
towards and
landed on the surface of Titan. The data, retrieved through telemetry
packets, showed the PSA to be working well with potential for actual
radio
science investigations.
The Huygens PSA on Cassini consists of two receivers operating at
different
S-band frequencies and at opposite polarizations. Only one of the two
channels utilized a Rubidium-based Receiver Ultra-Stable Oscillator
(RUSO)
as a frequency reference. The RUSO-based channel received the uplink
signal
from DSS-24 at Goldstone, CA, which was transmitted at 20 kW uplink
power at
~ 2040 MHz. There was no tuning of the uplink; a fixed, carefully
selected
frequency was transmitted. The sequence of events was designed such
that
the command to power-on the RUSO and PSA was coincident with the
arrival of
the uplink signal. This allowed the observation of the warm-up
process.
The entire activity lasted for one hour.
This reverse occultation demonstration could pave the way toward
future
occultation observations with signal-to-noise ratios hundreds of times
greater than traditional occultation observations, allowing Cassini
scientists to probe deeper into the atmosphere of Saturn and Titan,
through
the denser regions of Saturn's B ring, and during solar conjunctions.
Monday, November 5 (DOY 309)
A kick-off meeting was held today for a Rhea-Saturn live update for
DOY
320-321. After analysis and review by representatives from the
Composite
Infrared Spectrometer, Radar, Ultraviolet Imaging Spectrograph (UVIS),
and
Science Planning teams, it was determined that pointing was still
within
tolerance and the update would not be needed.
Tuesday, November 6 (DOY 310)
The S38 Science Operations Plan update official port occurred today.
This
process will complete on Wednesday, Nov. 21.
As part of the "SCIENCE 101- A Science Lecture Series For The
Non-Scientist", a member of the Cassini UVIS instrument team gave a
presentation today in Von Karman Auditorium at JPL on exploring the
icy
moons of Jupiter and Saturn.
Wrap up:
Check out the Cassini web site at http://saturn.jpl.nasa.gov for the
latest
press releases and images.
The Cassini-Huygens mission is a cooperative project of NASA, the
European
Space Agency and the Italian Space Agency. The Jet Propulsion
Laboratory, a
division of the California Institute of Technology in Pasadena,
manages the
Cassini-Huygens mission for NASA's Science Mission Directorate,
Washington,
D.C. JPL designed, developed and assembled the Cassini orbiter.
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