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Cassini Significant Events 11/24/10 - 11/30/10 The most recent spacecraft telemetry was acquired on Nov. 30
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, Nov. 24 (DOY 328) A status update titled "Cassini Back to Normal, Ready
for Enceladus" was released today and posted on the Cassini web site. The
Cassini spacecraft resumed normal operations today. All science instruments
have been turned back on, the spacecraft is properly configured, and Cassini is
in good health. Mission managers expect to get a full stream of data during the
upcoming flyby of the Saturnian moon Enceladus on Tuesday, Nov. 30. Cassini
went into safe mode on Nov. 2, when one bit flipped in the onboard command and
data subsystem computer. Engineers have determined that all spacecraft responses
were proper when it entered into a standby mode, but still do not know why the
bit flipped. The recovery from safing is complete. For more information on this
subject link to: http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20101124/ The Stellar Reference Unit (SRU) calibration that was
originally scheduled to take place via the S64 background sequence on Nov. 17,
but was not due to the safing, was executed today via a real time command. The S65 sequence began execution today at 2010-328T19:35:00.
The sequence will run for 54 days and conclude on Jan. 17. During that time
there will be two targeted encounters of Enceladus and one of Rhea, and
fourteen non-targeted flybys - five of Titan, two of Pandora, and one each of
Hyperion, Atlas, Janus, Dione, Pan, Daphnis, and Methone. Eight OTMs are
scheduled, numbered 268 through 275. This week, the first week of the S65 background sequence,
the science observations began during the apoapse portion of Orbit 141, inbound
to periapsis. Included were a 13 hour interstellar dust campaign by the Cosmic
Dust Analyzer (CDA) and a 13.5 hour observation of the low latitude plasma
environment by the Cassini Plasma Spectrometer (CAPS). Next, the Composite
Infrared Spectrometer (CIRS), the Imaging Science Subsystem (ISS), and the
Visual and Infrared Mapping Spectrometer (VIMS) performed an observation of
Titan as part of the Titan monitoring campaign to search for variability in the
thick atmosphere of this large moon. The Ultraviolet Imaging Spectrograph
(UVIS), CIRS, ISS and VIMS performed an 11 hour observation of Saturn's aurora.
Unique observations of the spongy-looking, chaotically spinning moon Hyperion
were made in a 13 hour block and a 5 hour block by ISS, UVIS, VIMS and CIRS.
UVIS performed an 11 hour observation of Rhea to map ultraviolet albedo as a
function of longitude and phase angle; CIRS and VIMS participated in the
observation as well. Approaching periapsis, at a distance of about 7 Saturn
radii, CDA made an observation of a ring shadow crossing. Thursday, Nov. 25 (DOY 329) Office moves continued this week within the Cassini Project
area. So far, 55 out of 60 office moves have been completed. This task is
slated for completion by next month, when all 60 moves will be completed in
support of the transition to the new, descoped Solstice mission, and the
accommodation of other Projects moving into the operations building. Judges have selected U.S. winners for the Cassini Scientist
for a Day essay contest. There were nine U.S. winners (one winner per essay
topic per grade category) out of 1,000 students from 67 classrooms in 23 states
who entered the essay contest. The winning students come from Virginia,
Connecticut, Nebraska, California, New Jersey, Illinois, Missouri, and New
York. Names will be announced next week following the live Ustream webcast on
Dec. 7. Students are emailing their Saturn questions to
scientistforaday@xxxxxxxxxxxx by December 1, to be answered during the December
7 Ustream event. Friday, Nov. 26 (DOY 330) A feature story called "Thin Air: Cassini Finds
Ethereal Atmosphere at Rhea" is available on the Cassini web site. It
describes how Cassini has detected a very tenuous atmosphere known as an
exosphere, infused with oxygen and carbon dioxide, around Saturn's icy moon
Rhea. This is the first time a spacecraft has directly captured molecules of an
oxygen atmosphere albeit a very thin one -- at a world other than Earth. The
oxygen appears to arise when Saturn's magnetic field rotates over Rhea. For
more information on this subject link to: http://saturn.jpl.nasa.gov/news/cassinifeatures/feature20101126/ Saturday, Nov. 27 (DOY 331) Orbit Trim Maneuver (OTM) #268 was performed today. This was
the approach maneuver setting up for the Enceladus 12 (E12) encounter on Nov.
30. The Reaction Control Subsystem (RCS) burn began at 9:44 AM PST. Telemetry
immediately after the maneuver showed a burn duration of 55.875 seconds, giving
a delta-V of 0.064 m/s. All subsystems reported nominal performance after the
maneuver. Sunday, Nov 28 (DOY 332) The main engine cover was closed today for the periapsis
dust crossing, and the Attitude and Articulation Control Subsystem (AACS)
secondary safe table value was set to 170 degrees in preparation for the E12
flyby. Monday, Nov. 29 (DOY 333) A lunchtime seminar titled "Microwaving Titan" was
presented today by a Cassini RADAR team member. This talk described the present
understanding of Titan's surface and how the radar and radiometer worked
together to better understand the nature of its surface. This event was
sponsored by the Science Division. Tuesday, Nov. 30 (DOY 334) Today Cassini flew by Enceladus at an altitude of 47.9
kilometers and a speed of 6.3 km/sec. Closest approach occurred at
2010-334T11:53 at latitude of 61.1°N. This flyby was optimized for Radio
Science (RSS) gravity observations. There were two 3-hour "wing"
observations before and after closest approach, and then three more hours
centered directly around closest approach. Between RSS observations, ISS and
CIRS observed this moon on the inbound leg, and CIRS and VIMS took data on the
outbound leg. The focus of this ~50 kilometer altitude, northern hemisphere
flyby is the study of Enceladus's gravity and interior. The Cassini radio
science subsystem (RSS) measured subtle variations in the Enceladus gravity
field as the Cassini spacecraft flew by. For more information link to: http://saturn.jpl.nasa.gov/mission/flybys/enceladus20101130/ The most recent Cassini-Huygens Analysis and Results of the
Mission (CHARM) teleconference was held today. The topic: "Unveiling
Titan: A World Strange and Familiar". The Cassini mission has unveiled a
world that experiences surface temperatures about 200 degrees colder than
Earth's, receives 100 times less sunlight, where hydrocarbon molecules rain
from the sky and water ice is as hard as rock. This presentation is a review of
the discoveries of the recent flybys of Titan with focus on what has been
learned about its lakes, their seasonal evolution, and the hypothesis that they
undergo cyclic changes over tens of thousands of years, analogous to (Croll)
Milankovitch climate cycles on Earth. A PDF of the presentation package may be
obtained at: http://saturn.jpl.nasa.gov/video/products/MultimediaProductsCharm/ A news release called "Cassini Finds Warm Cracks on
Enceladus" is available on the Cassini web site. New images and data from
the Cassini spacecraft give scientists a unique Saturn-lit view of active
fissures through the south polar region of Saturn's moon Enceladus. They reveal
a more complicated web of warm fractures than previously thought. For more
information on this subject and images, link to: http://saturn.jpl.nasa.gov/news/newsreleases/newsrelease20101130/ ------------------------ To unsubscribe from Cassini Spacecraft Updates or to
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