Cassini Significant Events
for 09/10/08 - 09/16/08
The most recent spacecraft telemetry was acquired on Sept. 16 from
the Deep Space Network tracking complex at Goldstone,
California. 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/operations/present-position.cfm.
Wednesday, Sept. 10 (DOY 254):
Science activities today began with the Cassini Plasma Spectrometer
(CAPS) leading a Magnetospheric and Plasma Science (MAPS) auroral
investigation. After turning to Earth and downlinking this data, the
spacecraft stayed Earth pointed as the rings of Saturn passed between
Earth and the spacecraft. This provided an opportunity for a Radio
Science (RSS) ring occultation experiment. Cassini used its radio
transmitter to send multiple frequency radio signals through the
rings. Scientists carefully monitor the signals as they are received
on Earth. This allows them to deduce the structure and composition
of the rings. The day ended with a joint Optical Remote Sensing
(ORS) campaign of Saturn’s south polar region.
A non-targeted flyby of Epimetheus occurred today.
Science Planning, Composite Infrared Spectrometer (CIRS), Imaging
Science (ISS), Ultraviolet Imaging Spectrograph (UVIS), and Visual
and Infrared Mapping Spectrometer (VIMS) teams weighed in today at
the Go/No Go meeting for the first S44 Live IVP Update. It’s a go
for updates to Saturn, Cassini, and Enceladus vectors to execute on
DOY 161. Uplink of the necessary files is planned for next Monday.
The Cassini Radio Science (RSS) S43 orbit 84 rings chord occultation
was completed on Wednesday, Sept. 10. The experiment was covered by
Madrid’s DSS-63 station with X- and S-band support, and DSS-54 with
X- and Ka-band support. This was the last in a family of four fast
chord occultations that probed the rings when the opening angle was
small, about 5 to 7 degrees. This was also the first time DSS-54
provided RSS occultation experiment support. DSS-55 at Madrid is
usually scheduled to support the RSS Ka-band activities, but since
that antenna is currently down for upgrades and maintenance, DSS-54
was scheduled instead.
A nice image of the Anthe ring arc around Saturn was Astronomy
Picture of the Day today. The image may be seen at:
http://antwrp.gsfc.nasa.gov/apod/ap080910.html
Thursday, Sept. 11 (DOY 255):
Sequence Team leads uplinked the S44 background sequence today. In
addition, a CIRS noise test and flight software patches to instrument
FSW version 5.0.4 were also uplinked. The patches will be used to
determine the best way to remove certain types of noise from the CIRS
science data. Following the results of the noise tests, a permanent
patch to the CIRS FSW will be made. The permanent patch will decrease
the odds of the CIRS scan mechanism becoming stuck by increasing a
timing constraint the software uses in controlling the
mechanism. The current CIRS commands will execute on DOY 259.
Saturday, Sept. 13 (DOY 257):
Science activities at the end of S43 included a continuation of an
orbit determination study performed by ISS on some of the
lesser-known Saturnian satellites. Next, UVIS, CIRS, and ISS
observed Saturn’s moon Rhea for six and a half hours to look for
trace volatile elements. This was followed by ISS images of the
G-Ring arc and an opportunistic “mutual event” image of Dione
transiting across Enceladus. Finally, CAPS led another MAPS survey
of the magnetic and plasma environment of Saturn.
The S43 sequence concluded and S44 began execution today at
2008-257T23:44 SCET. The sequence will run for 35 days and conclude
on Oct. 18. During that time there will be a targeted encounter of
Enceladus and fifteen non-targeted flybys - two each of Titan,
Tethys, and Pallene, and one each of Pandora, Mimas, Calypso,
Daphnis, Atlas, Pan, Telesto, Janus, and Epimetheus. Five maneuvers
are scheduled, numbered 164A, and 165 through 168,
Monday, Sept. 15 (DOY 259):
A presentation on “Missing Noble Gases from the Titan Atmosphere”
was given today at JPL. The noble gases are a group of chemical
elements with very similar properties; under standard conditions,
they are all odorless, colorless, monatomic gases, with a very low
chemical reactivity. The six noble gases that occur naturally are
helium, neon, argon, krypton, xenon, and the radioactive radon. The
melting and boiling points for each noble gas are close together,
differing by less than 10 degrees Celsius; consequently, they are
liquids only over a small temperature range.
Sequence leads sent commands to the spacecraft today for a Cosmic
Dust Analyzer (CDA) ring plane crossing activity and a noise test,
and for the S44 Live Inertial Vector Propagator (IVP) Update #1. All
files have properly registered on-board the spacecraft.
Tuesday, Sept. 16 (DOY 260):
A non-targeted flyby of Titan occurred today.
The S46 Science Operations Plan product was handed off to the
Sequence Team today and the final sequence development process for
S46, the Science and Sequence Update Process, began. Items still to
be closed are RADAR requests for testing of the T48 and T49 Titan
flybys in the Integrated Test Laboratory, and establishing a schedule
and resources for the three Live IVP updates scheduled in S46.
Today a talk was presented on “Saturn’s moon Titan: View from
Cassini’s RADAR Mapper.” Case studies using Synthetic Aperture Radar
(SAR) and high-resolution radiometry data for geological mapping and
characterization of Titan’s surface were presented. Emphasis was on
flows and drainage patterns, geology, crater structures, dunes,
lakes, and evidence of structural control on drainage and flow
features in the Hotei area. Suggestions were also presented on
opportunities for data synergy between SAR/high-resolution
radiometry/VIMS for geological mapping and SAR/altimetry/VIMS for
surface and subsurface studies.
Visit the JPL Cassini home page for more information about the
Cassini Project: http://saturn.jpl.nasa.gov/
Cassini Significant Events
for 09/17/08 - 09/23/08
The most recent spacecraft telemetry was acquired on Sept. 23 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/operations/present-position.cfm.
Wednesday, Sept. 17 (DOY 261):
The Fall 2008 edition of the Cassini Scientist for a Day essay
contest was launched on Sept. 16. The contest is open to all grade
5-12 students in the United States. Participating students will be
competing in one of three groups, grades 5-6, grades 7-8, and grades
9-12. Targets for this contest are Tethys, Titan, and
Mimas. Students will write a 500-word essay defending their
selection of one of these three targets. The essay contest has a
deadline of Oct. 30, 2008, and Cassini will obtain the images on Nov.
26, 2008. Winners will be invited to participate in a teleconference
with Cassini scientists. For more information, videos, and complete
contest rules, teachers and students can visit the contest website
at: http://saturn.jpl.nasa.gov/education/scientist/6th_edition/
A flyer summarizing the contest can be found at:
http://saturn.jpl.nasa.gov/education/scientist/6th_edition/resources.cfm
Any questions regarding the contest should be e-mailed to:
scientistfora...@jpl.nasa.gov
Non-targeted flybys of Pandora, Mimas, Calypso, and Daphnis occurred
today.
The final integrated S49 sequence segments for orbits 106 - 110 are
due from the Target Working Teams and Orbiter Science Teams
today. These integrated products will be in sequence level form and
ready for the start of Science Operations Plan implementation.
Science teams will begin work on their pointing designs on Sept.
19. The final Cassini DSN station requests will also be delivered to
the DSN schedulers on the 19th. The official kick-off meeting for
S49 is scheduled for Oct. 1.
Wednesday was a busy day on the spacecraft as Ultraviolet Imaging
Spectrograph (UVIS) and Visual and Infrared Mapping Spectrometer
(VIMS) observed stars passing behind the rings, the Composite
Infrared Spectrometer (CIRS) observed Enceladus in eclipse behind
Saturn to look for sources of endogenic energy in the south polar
region, the Magnetospheric and Plasma Science (MAPS) instruments
collected at increased rates to observe auroral magnetosphere and
Saturn Kilometric Radiation source regions, and the Imaging Science
Subsystem (ISS) Narrow Angle Camera (NAC) performed non-contiguous
azimuthal scans of the rings targeted on a particular ringlet, the A
ring group, and observed Enceladus at an intermediate phase angle to
monitor plume activity.
Thursday, Sept. 18 (DOY 262):
The Main Engine (ME) cover was opened today. It has been closed for
the last 25 days, having been closed (deployed) on Aug. 24. This
completes the 44th cycle of the cover. During that time there were
only a few potential dust hazards, but since the time frame included
Superior Conjunction - a time of possible limited communication with
the spacecraft - and the Project has a policy of limiting the number
of cover cycles, it made good sense to just keep it closed until the
next main engine burn. The next cover deployment is on Sept.
21. For that cycle the cover will remain closed for four days and
will reopen on Sept. 25.
Friday, Sept. 19 (DOY 263):
Reading, Writing and Rings (RWR) has been published in the September
2008 issue of the National Science Teachers Association (NSTA)
journal “Science and Children,” and awarded a SciLinks from the
National Science Teachers Association. This means key textbook
subjects will be linked to RWR as an NSTA approved web
page. SciLinks has registered more than 156,000 teachers and nearly
640,000 students. In addition, representatives from the publication
Education Week shadowed our partners, the Bay Area Writing project,
as they began beta testing the outreach follow-on language arts
product “Through the Eyes of a Scientist.” Education Week.org
circulation has about 725,000 registered users.
Science today began with nine hours of VIMS observing as a star
occulted the outer C Ring. After a 9-hour downlink, CIRS continued
its campaign to thermally map and monitor the rings. Finally today
completed with an ISS lit-side low phase ring movie to search for
spoke periodicities.
Saturday, Sept. 20 (DOY 264):
Commands were sent to the spacecraft today for Orbit Trim Maneuver
#164a, a real-time reaction wheel bias to execute over the 164a
backup pass, Live Update #2 to execute on DOY-268, and a CDA ring
plane crossing activity for DOY-269.
Orbit Trim Maneuver (OTM) #164a was performed today. This is the
cleanup maneuver from the Enceladus 4 encounter on Aug. 11. The main
engine burn began at 1:15 PM PDT. Telemetry immediately after the
maneuver showed the burn duration was 5.3 seconds, giving a delta-V
of 0.88 m/s. All subsystems reported nominal performance after the
maneuver.
On Sunday the spacecraft will again be primarily taking data with the
NAC. The camera will begin with orbit determination observations of
several small satellites, including Pan, Epimethius, Prometheus, and
Janus. Next an image will be taken as part of a Titan cloud
monitoring campaign. Then the camera turns to Rhea for a low phase
angle observation with UVIS riding along. Coming into the home
stretch, three optical navigation images are taken, and to end the
day, images of Mimas with UVIS again riding along are planned.
Monday, Sept. 22 (DOY 266):
Teams made the first delivery today as part of the Science Operations
Plan process for S48.
Tuesday, Sept. 23 (DOY 267):
An AACS Periodic Engineering Maintenance was completed on the
spacecraft today. In addition, a friction test of the backup
reaction wheel (RWA) was performed. For this test, performed every
six months, the RWA is spun up to 600 rpm in both the clockwise and
counterclockwise directions and timed as it is allowed to run down to
zero.
The third potential Live Update for S44 would cover DOY 275-277 and
modify vectors for Saturn and Tethys. Science Planning has already
performed some analysis and finds the errors are minimal, and is
recommending a NO-GO for the live update. CIRS, ISS, and UVIS have
observations of designated targets during this period and will be
responding over the next day or so with their inputs to the decision.
Cassini Significant Events
for 09/24/08 - 09/30/08
The most recent spacecraft telemetry was acquired on Sept. 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/operations/present-position.cfm.
Wednesday, Sept. 24 (DOY 268):
The Optical Remote Sensing (ORS) instrument teams and the Science
Planning team have all confirmed that live update #3 for Saturn and
Tethys on DOY 275-277 is not required and may be cancelled.
An AACS friction test of the backup reaction wheel (RWA) #3 was
completed Sept. 23. For this test, performed every six months, the
RWA is spun up to 600 rpm in both the clockwise and counterclockwise
directions and timed as it is allowed to run down to zero. Results,
compared with the previous friction test performed on this wheel on
Apr. 6, showed no significant changes.
An encounter strategy meeting was held today to review the period
between Oct. 9 and Nov. 3, the Enceladus 5 and 6 flybys, Titan 46,
and maneuvers 167-169.
Science activities today began with VIMS observing the bright star
Gamma Crucis as it was occulted by the rings. This was followed by a
downlink to Madrid, then VIMS scanning the unlit side of the rings,
and UVIS observing a stellar-ring occultation. The day finished with
a unique observation of Tethys as it passed through Saturn
eclipse. All ORS instruments took data, with CIRS having prime
pointing control to observe the thermal response of Tethys as it
passed into Saturn’s shadow.
Thursday, Sept. 25 (DOY 269):
Non-targeted flybys of Tethys, Atlas, Pan, and Pallene occurred today.
Today began with the spacecraft passing through periapsis, the point
where the spacecraft is closest to Saturn for this orbit. During
periapsis, Magnetospheric and Plasma Science (MAPS) instruments
collected data at increased rates to observe the auroral
magnetosphere and Saturn Kilometric Radiation source region. Later,
when the spacecraft turned to Earth to play back data to Goldstone,
Radio Science transmitted Ka-band frequency data to characterize the
Saturn gravity field.
Friday, Sept. 26 (DOY 270):
Heading away from periapsis, Friday began with a small satellite
orbit determination activity. Then the ORS instruments used a
relatively close Rhea encounter to acquire moderate resolution
imaging data for geologic mapping. During the middle part of the day
the spacecraft transmitted data back to Earth, and for the last part
of the day ISS took data for an approximately10 hour ring movie to
search for possible spokes and periodicities.
Monday, Sept. 29 (DOY 273):
Cassini Outreach, the JPL Education Office, the Laboratory for
Atmospheric and Space Physics, and Cassini mission engineers and
scientists will be participating in an educator workshop from Sept.
29 through Oct. 6 in Tennessee. The purpose of the workshop is to
test the next iteration of language arts “Through the Eyes of a
Scientist” with educators, the Eastern Tennessee State University
Center for Excellence in Mathematics and Science Education, and the
International Storytelling Center.
All sequence participants delivered Port 3 files as part of the S47
Science Operations Plan Implementation process. A merge of all
submitted files has been performed, and Science Planning analysis of
the merge will be available Sept. 30.
Tuesday, Sept. 30 (DOY 274):
Over the weekend the ORS instruments performed a coordinated
observation of the icy moon Mimas, taking data for longitudinal and
phase coverage, and spectroscopy data to measure composition. Today
the spacecraft is operating quietly out near apoapsis beginning with
a 9-hour downlink to Madrid after which ISS performed a small
satellite orbital determination activity. The cameras then turned
towards Titan to continue the cloud monitoring campaign. The day’s
activities finished with an approximately 12 hour medium resolution F
ring movie.
Visit the JPL Cassini home page for more information about the
Cassini Project: < http://saturn.jpl.nasa.gov/>
Cassini Significant Events
for 10/01/08 - 10/07/08
The most recent spacecraft telemetry was acquired on Oct. 7 from the
Deep Space Network tracking complex at Goldstone, California. 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/operations/present-position.cfm.
Wednesday, Oct. 1 (DOY 275):
The Cassini-Huygens Analysis and Results of the Mission (CHARM)
teleconference for September was held last week. The topic: Cassini
Composite Infrared Spectrometer (CIRS): Instrument, Operations, and
Science.
The Science Operations Plan kickoff meeting for the S49 sequence was
held today. Files to be delivered for the first port are due Oct. 23.
Thursday, Oct. 2 (DOY 276):
A non-targeted flyby of Tethys occurred today.
Orbit Trim Maneuver (OTM) #165 was performed today. This is the
periapsis maneuver setting up for the Enceladus 5 encounter on Oct. 9.
The main engine burn began at 4:44 AM PDT. Telemetry immediately after
the maneuver showed the burn duration was 23.71 seconds, giving a
delta-V of 3.93 m/s. All subsystems reported nominal performance after
the maneuver.
The main engine cover was closed today at end of the OTM-165 prime
window for a dust hazard. It was reopened about 2.5 hours later. This
was cycle #46 for the cover.
Heading into Saturn periapsis, activity on-board the spacecraft has
increased. The day began with a short high resolution F ring stare by
the narrow angle camera. Meanwhile, the Magnetospheric and Plasma
Science (MAPS) teams collected data at increased rates. Of particular
note, the Radio and Plasma Wave Science (RPWS) instrument performed a
“whistler” activity. Whistler observations are used to obtain wideband
evidence of lightning whistlers which would verify the existence of
lightning already suspected from Saturn Electrostatic Discharges (SED)
and provide information on the electron density along the field line
to
the source. After this, the spacecraft turned to Earth to downlink the
data and clear the SSRs in preparation for receipt of periapsis data.
The downlink was interrupted briefly for OTM-165, the final
deterministic maneuver before Enceladus 5.
Following the downlink, MAPS had prime pointing to observe the auroral
magnetosphere and Saturn Kilometric Radiation source region. MAPS and
Optical Remote Sensing (ORS) teams coordinated the pointing and timing
closely so that CIRS could observe Tethys as it was eclipsed by
Saturn.
Finally, the last short activity of periapsis science was a joint
Ultraviolet Imaging Spectrograph (UVIS), Visual and Infrared Mapping
Spectrometer (VIMS), Imaging Science Subsystem (ISS), and CIRS
campaign
to study the auroras at Saturn’s poles.
Friday, Oct. 3 (DOY 277):
A non-targeted flyby of Titan occurred today.
The spacecraft was busy executing many short duration activities. The
first was ISS with another observation set in the campaign for small
satellite orbit determination. Next, the Cassini Plasma Spectrometer
(CAPS) took pointing control of the spacecraft for MAPS instruments to
collect enhanced survey data. After CAPS, the spacecraft turned
towards
Earth to downlink science data. During the downlink, Radio Science
(RSS)
performed an Operational Readiness Test to demonstrate DSN and RSS
preparedness to support the orbit 89 rings occultation experiment on
DOY
291. Following the downlink, CIRS took a thermal scan of the rings.
VIMS
had the next activity, again observing a stellar-ring occultation,
this
time of the outer A-ring region. Afterwards, the full suite of ORS
instruments observed Mimas to collect additional longitudinal and
phase
angle coverage. The day concluded with ISS taking another series of
small satellite orbital determination images plus one Titan cloud
monitoring image.
Monday, Oct. 6 (DOY 280):
Orbit Trim Maneuver (OTM) #166 was performed today. This is the
approach
maneuver setting up for the Enceladus 5 encounter on Oct. 9. The
reaction control subsystem burn began at 12:29 PM PDT. Telemetry
immediately after the maneuver showed the burn duration was 8.13
seconds, giving a delta-V of 14.96 mm/s. All subsystems reported
nominal
performance after the maneuver.
The Oct. 9 flyby of Enceladus is the first of two to occur in October.
This is the closest flyby yet of any moon of Saturn, at only 25
kilometers from the surface. The Oct. 31 flyby is farther out, at 196
kilometers. During the Oct. 9 flyby, the on-board fields and particles
instruments will venture deeper into the plume than ever before,
directly sampling the particles and gases. The emphasis here is on the
composition of the plumes rather than imaging the surface. On Oct. 31,
the cameras and other optical remote sensing instruments will be front
and center, imaging the fractures that slash across the moon’s south
polar region. For more information link to:
http://saturn.jpl.nasa.gov/news/press-release-details.cfm?newsID=874
The NASA blog is active once again for the E5 flyby on Oct. 9. To
participate, link to: http://blogs.nasa.gov/cm/blog/enceladus
Closest approach will occur on Oct. 9 at 1:30 PM Pacific Time. Just 29
seconds after closest approach, Cassini will fly directly over the
South
Pole at an altitude of 339 kilometers. The first data will hit the
ground at about 2:30AM Pacific Time on Oct. 10.
Tuesday, Oct. 7 (DOY 281):
The main engine cover was closed today at the end of the OTM-166
backup
window for a potential dust hazard as part of the Enceladus 5 flyby on
Oct. 9. It will be opened after the flyby on Oct. 10. This will be
cycle
#47 for the cover. Spacecraft Operations (SCO) hosted the S50
Engineering Activities Review today. The objective of the meeting is
for
SCO and Navigation to take a long look ahead - S50 executes in May of
2009 - and determine whether there are any periods or activities where
contingency planning might be appropriate.
As part of the sequence development process for S46, the RADAR team
requested that their designs for the Titan T48 and T49 flybys be
simulated in the ITL. The simulations will begin today and continue
through the weekend.
Cassini Significant Events
for 10/08/08 - 10/14/08
The most recent spacecraft telemetry was acquired on Oct. 14 from the
Deep Space Network tracking complex at Goldstone, California. 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/operations/present-position.cfm.
Wednesday, Oct. 8 (DOY 282):
Port 2 spacecraft activity sequence files for the S48 sequence were
delivered today as part of the Science Operations Plan development
process. The merged products and Science Planning (SP) assessment
will be released tomorrow.
Cassini is currently in a part of Extended Mission that is proving to
be a challenge for the flight team. From the Navigation (NAV)
perspective, the Enceladus 6, Titan 46 combination is unique even
among the existing three double flybys. It is almost a pi-transfer
from E6 ~periapsis to T46 ~ apoapsis, but without a maneuver in
between.
From a science perspective, Radio Science (RSS) made the case that
Titan must be targeted, rather than Enceladus, due to attitude and
timing sensitivity of the occultation and bi-static experiments at
closest approach. The Inertial Vector Definition (IVD) pointing
designs for RSS are built into the S45 background sequence and cannot
be updated at this late stage. On the other hand, it has been
pointed out that E6 presents the last opportunity for lit viewing of
the tiger stripes and the “skeet shoot” planned by Imaging Science
(ISS) is unique in its implementation.
After some discussions between NAV, SP, and Uplink Operations (ULO),
it looks like performing a live Inertial Vector Propagator (IVP)
update for E6 pointing vectors can be accommodated. This allows NAV
to continue targeting to T46 and gives some amount of flexibility to
E6 instrument pointing.
The current best-available prediction using the orbit determination
(OD) solution following Orbit Trim Maneuver (OTM) #166 shows the E6
flyby altitude is 15 km lower and occurs 0.26 sec later than on the
trajectory for which the observations were designed. The actual live
update will use a special OD released by NAV on Monday, Oct. 20. The
first uplink window for the update is on Oct. 28. That gives the
team eight days - including weekends - to obtain the OD, and analyze
the product to determine if an update is indeed necessary. If so,
they will need to build the products updating vectors for near
closest approach, have them approved, and get them on the spacecraft
in time for the E6 flyby on Halloween, Oct. 31.
For more information on pi-transfers and the “skeet-shoot” technique
used by ISS, look up the Cassini Significant Events Reports covering
Sept. 14, 2006, and Aug. 15, 2008.
Thursday, Oct. 9 (DOY 283):
Non-targeted flybys of Telesto and Janus occurred today.
On Thursday the spacecraft encountered Enceladus for the E5 targeted
flyby at an altitude of only 25 km, making it the closest flyby of
the Cassini mission. Closest approach occurred at approximately 12:31
PM PDT, at a speed of 17.7 km/sec, latitude 28 degrees S, and
longitude 97 degrees W. Just 29 seconds after closest approach,
Cassini flew directly over the South Pole at an altitude of 339
kilometers. The flyby focused on Magnetosphere and Plasma Science
(MAPS) instruments that sniffed and tasted the composition of the icy
plumes emanating from the southern pole of Enceladus. See the
Enceladus E5 mission description for full details of the science
activities occurring during the
flyby:
<http://saturn.jpl.nasa.gov/multimedia/products/
mission_descriptions.cfm>http://saturn.jpl.nasa.gov/multime
dia/products/mission_descriptions.cfm
Friday, Oct. 10 (DOY 284):
Following the E5 flyby, Spacecraft Operations (SCO) performed a
checkout of Sun Sensor Assembly #B as part of normal maintenance.
The Main Engine (ME) cover was opened on October 10, 2008. This was
cycle #47.
Beginning today, Cassini outreach will be at the Division of
Planetary Sciences conference at Cornell University, Ithaca, NY,
supporting outreach activities for that week-long event. Cornell
University’s Herbert F. Johnson Museum of Art is currently featuring
Spectacular Saturn: Images from the Cassini-Huygens Mission, on
display from September 20 through January 4. This exhibit displays
over fifty images of the planet Saturn, its rings, and satellites.
Image selection, by Cornell members of the Cassini project, was made
from almost two hundred thousand images that have been transmitted to
Earth since the Cassini spacecraft arrived at Saturn in 2004. A
1/10th scale model of the Cassini spacecraft is also on view as well
as historical books about Saturn from the Kroch Rare Book and
Manuscript collection. The exhibit will next travel to the
Smithsonian Air and Space Museum in Washington, D.C. where it will
appear until May 2009.
Following the Enceladus flyby, the spacecraft spent nearly 13 hours
today at Earth-point to downlink the science data collected during
the flyby. During the downlink, SCO opened the main engine cover in
preparation for the upcoming OTM-167, and RSS used the time at Earth
point to acquire Ka-band frequency data for improving Saturn
gravitational field models, as well as performing an Operations
Readiness Test (ORT) to demonstrate DSN and RSS preparedness to
support the orbit 89 rings occultation experiment on DOY-291. Friday
concluded with the Ultraviolet Imaging Spectrograph (UVIS) turning
back toward a fleeting Enceladus to map the particle composition of
the E ring in the immediate vicinity of Enceladus. These observations
will test the connection between changes in the E rings and plume
eruptions.
Saturday, Oct. 11 (DOY 285):
SCO and ULO uplinked commands today for OTM-167, to clear the
on-board error logs, and install Instrument Expanded Block (IEB)
files for ISS and VIMS in support of S45. The final approval meeting
for S45 is scheduled for Oct. 14, and execution begins on Saturday,
Oct. 18. The remaining seven IEB files will be uplinked on Monday,
Oct. 13.
Sunday, Oct. 12 (DOY 286):
The imaging team had control of the spacecraft for all of Sunday,
performing a variety of activities. Observations began with a
continuation of the long ring spoke movie from the previous day, and
narrow angle camera small satellite images for orbital
determination. Next was a coordinated Optical Remote Sensing (ORS)
activity of Tethys observations for longitudinal and phase angle
coverage. The cameras then pointed toward the rings for long term
temporal monitoring of the F ring. This was followed by a short
one-hour activity continuing coverage for small satellite orbital
determination. The last imaging activity on Sunday was a coordinated
ORS observation of Dione for longitudinal and phase angle coverage.
Before the day was finished, the spacecraft turned toward Earth to
play back science data to Canberra stations. During the downlink,
the flight team performed Orbit Trim Maneuver #167. This was the
cleanup maneuver from the Enceladus 5 encounter on Oct. 9. The main
engine burn began at 6:15 PM PDT. Telemetry immediately after the
maneuver showed the burn duration was 20.04 seconds, giving a delta-V
of 3.33 m/s, as planned. All subsystems reported nominal performance
after the maneuver.
Monday, Oct. 13 (DOY 287):
A close-up image of Enceladus was Astronomy Picture of the Day
today. Check it out at:
http://antwrp.gsfc.nasa.gov/apod/ap081013.htmlhttp://
antwrp.gsfc.nasa.gov/apod/ap081013.html
New images from Cassini reveal a giant cyclone at Saturn’s north
pole, and show that a similarly monstrous cyclone churning at
Saturn’s south pole is powered by Earth-like storm patterns. The
new-found cyclone at Saturn’s north pole is only visible in the
near-infrared wavelengths because the north pole is in winter, and
thus in darkness to visible-light cameras. For the complete story go
to:
<http://saturn.jpl.nasa.gov/news/press-release-details.cfm?
newsID=876>http://saturn.jpl.nasa.gov/news/press
-release-details.cfm?newsID=876
Cycle #48 of the Main Engine (ME) cover began today when it was
closed at the end of the OTM-167 backup uplink window for a dust
hazard coming up on Oct. 17. It will be reopened on the 17th after
the hazard has passed and before the OTM-168 prime uplink window.
Tuesday, Oct. 14 (DOY 288):
An AACS Reaction Wheel Assembly (RWA) friction test for prime wheels
number 1, 2 and 4 was executed Oct. 14. In this test, performed
every three months, the RWAS are normally spun up to 900 rpm in both
directions and timed as they are allowed to spin down to 0 rpm. This
time the coast down was started at +/-1200 rpm. This was in response
to the last friction test, performed June 18, where RWA-2 had a
significant worsening in the run-down time. This change should start
the rundown outside of the drag torque spike area, enabling a clean
viscous friction coefficient measurement, which was impossible with
the observed drag torque spikes, and redistribute the lubricant. SCO
will be analyzing the results this week.
Another beautiful close-up image of Enceladus, showing detail of one
of the tiger stripes, was Astronomy Picture of the Day today. Check
it out at:
http://antwrp.gsfc.nasa.gov/apod/ap081014.htmlhttp://
antwrp.gsfc.nasa.gov/apod/ap081014.html
Visit the JPL Cassini home page for more information about the
Cassini Project: http://saturn.jpl.nasa.gov/
Cassini Significant Events
for 10/15/08 - 10/21/08
The most recent spacecraft telemetry was acquired on Oct. 21 from the
Deep Space Network tracking complex at Goldstone, California. 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/operations/present-position.cfm.
Wednesday, Oct. 15 (DOY 289):
Today the Cassini flight team celebrated the 11th anniversary of
launch.
Today was relatively quiet for science activities. The beginning of
the day was devoted to completing the long F ring movie started the
day before. Afterwards the spacecraft turned toward Earth to
downlink science data to Goldstone DSN stations. The day finished
with a short Composite Infrared Spectrometer (CIRS) thermal map of
the main rings.
The S45 background sequence was radiated to the spacecraft over the
Goldstone DSS-15 pass today. Execution will begin on Saturday at
2008-292T20:21 Spacecraft Event Time (SCET).
Thursday, Oct. 16 (DOY 290):
The spacecraft is approaching periapsis and the level of science
activity is increasing. This makes sense if you remember that each
time the spacecraft reaches periapsis, it is the closest it will be
to Saturn for that orbit.
Today CIRS took data for a thermal map of the main rings. The Visual
and Infrared Mapping Spectrometer (VIMS) observed the bright star
Gamma Crucis as it passed behind rings F through D, and later scanned
the shaded portion of the unlit side of the rings. The imaging
cameras (ISS) had a short retargetable activity to search for
yet-undiscovered moons or ring features, and the Ultraviolet Imaging
Spectrograph (UVIS) observed a stellar-ring occultation, this time of
a bright ultra-violet star. After the Optical Remote Sensing (ORS)
instruments completed their observations, the Magnetospheric and
Plasma Science (MAPS) teams observed the auroral magnetosphere and
Saturn Kilometric Radiation source region.
Friday, Oct. 17 (DOY 291):
Non-targeted flybys of Palene and Epimetheus occurred today.
Orbit Trim Maneuver (OTM) #168 was performed today. This was a large
periapsis maneuver setting up for the Enceladus 6 flyby on Oct. 31,
and targeted Titan 46 encounter on Nov. 3. The main engine burn
began at 3:34 AM PDT. Telemetry immediately after the maneuver showed
the burn duration was 41.7 seconds, giving a delta-V of 7.0 m/s. All
subsystems reported nominal performance after the maneuver.
The maneuver was preceded by one of the early Extended Mission Radio
Science (RSS) ring occultations spanning a chord of the ring system.
For this observation, RSS observed at Ka, X and S band frequencies.
An unusually long 14-hour downlink block to accommodate a series of
navigation and engineering events followed. Prior to the maneuver,
Spacecraft Operations received telemetry confirming that the main
engine (ME) cover was open. The ME cover is used to protect the
engines from small particulates during ring plane crossings. Once the
OTM was complete, a real time Radio and Plasma Wave Science Whistler
observation was performed on thrusters during the backup maneuver
pass. These observations are designed to obtain wideband evidence of
lightning whistlers, would verify the existence of lightning already
suspected from Saturn Electrostatic Discharges (SED), and would
provide information on the electron density along the field line to
the source. The cover was closed again at the end of the pass for a
dust hazard that will occur on October 24. This was cycle #49 for
the ME cover.
Saturday, Oct. 18 (DOY 292):
The last science activities of the S44 sequence were a small
satellite orbit determination campaign by ISS, a CIRS thermal map of
the rings, and three optical navigation images for the Navigation
team. The spacecraft then turned toward Earth to downlink the
remainder of S44 science data before handing off to the next day and
next sequence.
The S44 sequence concluded and S45 began execution today at
2008-292T14:44 Pacific Time. The sequence will run for 40 days and
conclude on Nov. 26. During that time there will be two targeted
encounters of Titan and sixteen non-targeted flybys - two each of
Enceladus and Tethys, and one each of Titan, Janus, Pan, Mimas,
Methone, Pandora, Daphnis, Atlas, Epimetheus, Polydeuces, Telesto,
and Helene. Five OTMs are scheduled, numbered 169 through 173.
Sunday, Oct. 19 (DOY 293):
A non-targeted flyby of Titan occurred today.
The first day of the S45 sequence featured rings observations led by
VIMS and CIRS. VIMS made a mosaic of the lit side of the rings while
CIRS watched as the star CW Leo, a bright infrared source, passed
behind the rings. The Cassini Plasma Spectrometer (CAPS) ended the
day with almost two hours of dedicated studies of the Saturnian
magnetosphere.
Monday, Oct. 20 (DOY 294):
A beautiful image of Saturn with moons and rings is Astronomy Picture
of the Day today. Check it out at:
http://antwrp.gsfc.nasa.gov/apod/ap081020.htmlhttp://
antwrp.gsfc.nasa.gov/apod/ap081020.html
Today is the first day of a week-long Cassini Project Science Group
meeting. This is the 46th assembly of this group since the project
began its early stages of development back in the mid 1980s. This
week, Cassini scientists will come to JPL to participate in Saturn,
Icy satellite, Titan, Rings, and Magnetospheric working groups,
instrument team meetings, and to give status reports to those
assembled on work in progress.
Much of the day’s science activities involved ISS observations of
Mimas, Tethys, Titan and Saturn’s small satellites, as well as
Saturn’s G ring. In addition, UVIS studied the volatiles in the
vicinity of Enceladus to determine the nature of the relationship
between the very tenuous atmosphere at Enceladus and the plumes
emanating from that moon’s southern pole. To better study Saturn’s
magnetosphere, CAPS oriented the spacecraft for MAPS observations for
nearly five hours
Tuesday, Oct. 21 (DOY 295):
Closing out this week, ISS imaged Saturn’s main rings through a
combination of its filters to produce high-resolution color scans in
addition to continuing campaigns to monitor Saturn’s small satellites
and its F ring. UVIS performed a two-hour observation of the surface
of Dione.
Visit the JPL Cassini home page for more information about the
Cassini Project: http://saturn.jpl.nasa.gov/
Cassini Significant Events
for 10/22/08 - 10/28/08
The most recent spacecraft telemetry was acquired on Oct. 28 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/operations/present-position.cfm.
Wednesday, October 22 (DOY 296):
After two hours of magnetospheric studies led by the Cassini Plasma
Spectrometer (CAPS), the Navigation team obtained optical navigation
images as part of an ongoing activity to track Cassini with as much
accuracy as possible as it orbits Saturn. Following a 9-hour downlink
to Earth, Imaging Science (ISS) took another set of images in a
campaign to track the small satellites orbiting Saturn. This activity
was followed by a spacecraft roll designed to assist the Magnetometer
Subsystem (MAG) team calibrate the instrument’s sensors.
An encounter strategy meeting was held today to cover the period
between Nov. 3 and Nov. 19, Titan flybys T46 and T47, and maneuvers
170, 171 and 172.
With a tabletop walk-through today, Spacecraft Operations (SCO)
personnel began planning for a re-pressurization of the fuel side of
the bipropellant subsystem to maximize the delta-V available for the
mission. The procedure will be performed in January, 2009, and is the
last planned re-pressurization for the Cassini spacecraft.
Thursday, October 23 (DOY 297):
All teams and instruments delivered files today for Port 1 of the S49
Science Operations Plan process.
The Attitude and Articulation Control Subsystem (AACS) team kicked
off the AACS A8.7.7 flight software (FSW) update effort with a
working group meeting today. Parameter changes are planned to update
the default safing attitudes to support the time frame from June 2009
to July 2010, and to modify the default thruster magnitudes. Uplink
is planned in the late May/early June 2009 time-frame.
Friday, October 24 (DOY 298):
Non-targeted flybys of Janus, Pan, and Mimas occurred today.
The Magnetospheric and Plasma Science teams began science activities
today with observations of the auroral magnetosphere and Saturn
Kilometric Radiation source regions. This was followed by
occultation experiments with the Ultraviolet Imaging Spectrograph
leading a campaign to track the passage of a star behind the main
rings to probe the optical depth, and the suite of Optical Remote
Sensing instruments observing the Sun as it passed behind the rings.
After the occultations, ISS imaged Mimas to study the geology of that
moon, and then performed an azimuthal scan of the rings designed to
study the Columbo ringlet. The Composite Infrared Spectrometer
wrapped up the day by also performing ring studies.
Cycle #49 of the main engine (ME) cover concluded today after it was
stowed in preparation for Orbit Trim Maneuver (OTM) #169 to occur on
Oct. 29.
Monday, October 27 (DOY 301):
An image of the south pole of Saturn was Astronomy Picture of the Day
today. Check it out at http://antwrp.gsfc.nasa.gov/apod/ap081027.html
As a start to sequence implementation, the final integrated sequence
segments for S50, which includes orbits 110 - 112, are due from the
Target Working Teams today. Science Operations Plan implementation
then begins. A Science Planning Attitude Strategy Spreadsheet will
be delivered to the instrument teams on Oct. 29 so that they can
begin working on spacecraft pointing designs for this sequence.
Tuesday, October 28 (DOY 302):
CAPS oriented the spacecraft to optimize the acquisition of
magnetospheric data for the first two hours of the day. This was
followed by ISS searches for new small satellites and observations to
track known small satellites.
SCO and Uplink Operations uplinked the following to the spacecraft
today: OTM-169, a reaction wheel bias to execute over the OTM-169
backup pass on Oct. 30, the Enceladus 6 live update that will execute
Oct. 31, and a Cosmic Dust Analyzer mini-sequence for the E6 flyby,
also on Oct. 31.
The Cassini Scientist for a Day essay contest for U.S. students in
grades 5-12 has received a record number of entries. The entry
deadline is noon PDT on Oct. 30. Already 198 essays by 322 students
from 21 classrooms in 18 states have been received. The majority of
entries are usually submitted within the last 48 hours before the
contest deadline, so Outreach anticipates receiving many more entries
over the next two days.