Cassini Update - January 25, 2008
- From: baalke@xxxxxxxxxxxxx
- Date: Fri, 25 Jan 2008 09:03:51 -0800 (PST)
Cassini Significant Events
for 01/16/08 - 01/22/08
The most recent spacecraft telemetry was acquired on Tuesday, January
22,
from the Goldstone 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, January 16 (DOY 006):
The final S37 sequence approval meeting was held today. The sequence
will
be uplinked to the spacecraft on Sunday, Jan. 20, and begin execution
on
Tuesday, Jan. 22.
The S42 Spacecraft Engineering Activities Review was also held today.
The
review addressed activities to occur in the first sequence of the
proposed
extended mission. S42 begins execution on July 1, 2008.
Analysis of data from the T38, T39, and T40 Titan flybys was presented
today
by Ion and Neutral Mass Spectrometer (INMS), Attitude and Articulation
Control Subsystem (AACS), and Navigation teams at a Titan Atmosphere
Model
Working Group (TAMWG) meeting. The conclusion was that the
atmospheric data
from these southern hemisphere flybys were generally consistent with
previous flybys in the northern hemisphere and that there is no
indication
of any major atmospheric differences in time or hemisphere. There is
some
indication that southern hemisphere passes might be experiencing
slightly
less density than northern hemisphere passes, but the data are still
too
sparse to confirm that. There are small but unexplained differences
when
comparing the current passes to passes with similar altitude and
latitude in
the northern hemisphere relative to N2, CH4, and H2 abundances. T36
data
remains the lowest density measured under 1100 km. The next TAMWG
meeting
will be held concurrently with the Project Science Group meeting in
June of
this year. At this meeting the TAMWG will review the entire baseline
mission set of flybys to evaluate the safety of planned proposed
Extended
Mission flybys, and to recommend whether to adjust the current
atmosphere
model.
Thursday, January 17 (DOY 017):
Science observations today include Imaging Science (ISS) and the other
Optical Remote Sensing (ORS) observations of Rhea at low phase. ISS
will
also track the transit of Janus across Dione and make observations of
the
diffuse rings at low phase and elevation. The Visual and Infrared
Mapping
Spectrometer (VIMS) will observe the rings as the spacecraft crosses
the
ring plane to obtain more data for a ring plane-crossing movie.
Friday, January 18 (DOY 018):
Over the weekend from late Saturday to early Sunday morning,
Spacecraft
Operations will perform an annual Stellar Reference Unit calibration.
Monday, January 21 (DOY 021):
While the Composite Infrared Spectrometer (CIRS), Ultraviolet Imaging
Spectrograph (UVIS), and ISS were monitoring the F-ring, the Cosmic
Dust
Analyzer (CDA) was performing a software checkout/functional test.
The text
exercised version 12.0 instrument flight software (FSW) that was
uplinked
last week. A FSW demonstration is planned for the 27th and again in
early
February if needed. Cassini's 57th orbit of Saturn began late Monday
with
the spacecraft at an apoapse distance of 30.1 Rs and an orbit
inclination of
46.6 degrees.
Tuesday, January 22 (DOY 022):
A non-targeted flyby of Titan occurred today.
Near the end of S36, the RADAR instrument began warming up and
calibrating
for science data collection. By acting like a camera that uses
microwaves
instead of visible light, RADAR studied Titan's northern hemisphere
providing coverage of various northern latitudes along with some
associated
longitude variation. To obtain the correct polarization for these
observations, RADAR was in control of both the primary and secondary
axes of
the spacecraft.
The S36 sequence concluded and S37 began execution today at
2008-022T13:35:00 Spacecraft Event Time. The sequence will run for 25
days
and conclude on February 16, 2008. During that time there will be
nine
non-targeted flybys - two of each of Titan, Atlas, Epimetheus, and
Pandora,
and one of Prometheus. Only one maneuver is scheduled for S37,
OTM-144.
Key events for this sequence include a prime reaction wheel friction
test,
periodic engineering maintenance, and AACS A8.7.6 flight software
normalization.
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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