August 15th 05, 08:01 PM
Cassini Significant Events
for 08/04/05 - 08/10/05
The most recent spacecraft telemetry was acquired Wednesday, August 10,
from
the Madrid tracking stations. The Cassini spacecraft is in an excellent
state of health and is 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 .
Activities this week:
Thursday, August 04 (DOY 216):
Information was provided this week regarding the assessment meeting
that was
held August 3 about S18 aftermarket changes. It appears that all
requested
changes can fit within the available resources. Unless the
recommendations
of the Target Working Teams and Orbiter Science Teams change over the
next
couple of weeks, it is likely that the decision meeting scheduled in
two
weeks will be canceled.
Outreach provided information regarding some events that occurred over
the
previous weeks. July 24-30, Outreach presented, "Reading, Writing,
and
Rings" at the annual conference for students with exceptional needs.
Sixty
members of the education community who work with students with
physical,
mental, and emotional disabilities attended the conference, held in
Huntsville, Alabama.
The Chabot Space and Science Center in Oakland, California hosted a
3-day
workshop focusing on "Reading, Writing, and Rings". The workshop led
teachers through different activities as well as teaching techniques
developed in the lessons. Integration with standardized testing plans
and
state-adopted language arts curricula were included. In addition, a
mission
overview was presented to introduce teachers to different technical
aspects
of the mission. A Q&A session was held afterwards. The workshop ran
August
1-3, 2005 with 18 teachers attending.
Friday, August 05 (DOY 217):
An image advisory was released today on the satellite Mimas. The
Cassini
spacecraft found the Saturnian moon looking battered and bruised, with
a
surface that may be the most heavily cratered in the Saturn system.
The
August 2 flyby returned eye-catching images of its most distinctive
feature,
the spectacular 140 km diameter landslide-filled Hershel crater.
Numerous
rounded and worn-out craters, craters within other craters and long
grooves
reminiscent of those seen on asteroids are also seen in the new images.
The
new Mimas images are available at http://saturn.jpl.nasa.gov.
All teams and offices participated today in a Cassini/NASA quarterly
review.
The Titan Orbiter Science Team hosted a Preview Meeting covering the
Titan
T6, T7, & T8 encounters. The meeting was open to anyone on the flight
team
who was interested in a preview of the science objectives and
activities for
these three flybys.
Monday, August 08 (DOY 220):
Uplink Operations sent commands to the spacecraft for Visual and
Infrared
Mapping Spectrometer (VIMS) Instrument Expanded Block files, and for a
Cosmic Dust Analyzer decontamination activity that will execute on
Friday.
The Composite Infrared Spectrometer (CIRS) and Ultraviolet Imaging
Spectrograph (UVIS) instrument teams have now delivered 100 percent of
their
archive data from launch through September 2004 to the Planetary Data
System
(PDS)
The second archive delivery on October 1, 2005 will contain data
collected
from October 2004 to December 2004. The Magnetospheric Imaging
Instrument
team has already submitted their data for this period, and it has been
accepted by PDS.
Tuesday, August 09 (DOY 221):
A kick-off meeting was held today for the DOY 227 Live Inertial Vector
Propagator (IVP) update process. A Go/No Go meeting will be held
tomorrow.
UPDATE: At the Go / No-Go meeting it was determined that the original
satellite and spacecraft ephemeris information used in planning the
observation was still very accurate, and the update to the pointing was
not
necessary.
OK. So what is all this about Live IVP updates, OD solutions,
pointing,
etc. that you keep hearing about? Initial development for a sequence
may
occur years before it is time to finally dust it off, and execute it
on-board the spacecraft. In early development the Science community
will
identify satellites they wish to observe, but at the time, the exact
details
of where to point the spacecraft are not known. There is too much
uncertainty at that time to accurately predict where the satellite is
going
to be. It requires both the Navigation team's understanding of where
the
spacecraft is, and our knowledge of the location of the satellites in
order
to ensure accurate pointing. Things change over time, hence the
uncertainty
at the time of sequence development.
To ensure that the satellite data will be acquired when the sequence
finally
executes, the concept of live movable blocks and vector updates was
developed. Basically, for a limited number of observations, spacecraft
pointing for specific targets will be analyzed, and a small portion of
the
sequence modified to ensure we are looking in the right place. The
vectors
that are being updated are superceded - updated - as part of the live
update
process, thus providing accurate pointing to the satellites. Oh, and
this
all happens while the sequence is already executing. That is why it is
called a "live" update.
If changes to the spacecraft trajectory based on the Orbit Trim
Maneuvers
(OTM) leave us with the pointing necessary to acquire the satellites,
the
Live IVP update process ends at the No/Go meeting.
Wednesday, August 10 (DOY 222)
Orbit trim maneuver #27 (OTM-27), the "Titan 6 targeting" maneuver, was
successfully completed on the spacecraft. The main engine burn began
at
07:44 am PDT. A "quick look" immediately after the maneuver showed the
burn
duration was 15.5 sec long, giving a delta-V of 2.4 m/s. AACS,
Navigation,
Propulsion, Thermal, Power, and Fault Protection teams all reported
nominal
performance after the event.
Science activities this week included CIRS' continued monitoring of the
F-Ring as well as mapping of a region just south of Saturn's equator to
determine the local temperatures of the upper troposphere and
tropopause.
The Imaging Science Subsystem (ISS) took images of Pandora, Janus,
Helene,
Telesto, Methone, Prometheus, Epimetheus, and Pan for the purpose of
better
determining the orbits of these minor satellites.
The Magnetospheric and Plasma Science (MAPS) instruments conducted a
magnetospheric boundary campaign looking in the corotation direction.
The VIMS instrument carried out a regional aurora map, and as part of
instrument calibration observed Fomalhaut, a bright star with an
unexpected
amount of infrared radiation from the disk around it. UVIS also
performed
instrument calibration by observing Alpha Eri, the ninth brightest star
in
the sky.
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.
for 08/04/05 - 08/10/05
The most recent spacecraft telemetry was acquired Wednesday, August 10,
from
the Madrid tracking stations. The Cassini spacecraft is in an excellent
state of health and is 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 .
Activities this week:
Thursday, August 04 (DOY 216):
Information was provided this week regarding the assessment meeting
that was
held August 3 about S18 aftermarket changes. It appears that all
requested
changes can fit within the available resources. Unless the
recommendations
of the Target Working Teams and Orbiter Science Teams change over the
next
couple of weeks, it is likely that the decision meeting scheduled in
two
weeks will be canceled.
Outreach provided information regarding some events that occurred over
the
previous weeks. July 24-30, Outreach presented, "Reading, Writing,
and
Rings" at the annual conference for students with exceptional needs.
Sixty
members of the education community who work with students with
physical,
mental, and emotional disabilities attended the conference, held in
Huntsville, Alabama.
The Chabot Space and Science Center in Oakland, California hosted a
3-day
workshop focusing on "Reading, Writing, and Rings". The workshop led
teachers through different activities as well as teaching techniques
developed in the lessons. Integration with standardized testing plans
and
state-adopted language arts curricula were included. In addition, a
mission
overview was presented to introduce teachers to different technical
aspects
of the mission. A Q&A session was held afterwards. The workshop ran
August
1-3, 2005 with 18 teachers attending.
Friday, August 05 (DOY 217):
An image advisory was released today on the satellite Mimas. The
Cassini
spacecraft found the Saturnian moon looking battered and bruised, with
a
surface that may be the most heavily cratered in the Saturn system.
The
August 2 flyby returned eye-catching images of its most distinctive
feature,
the spectacular 140 km diameter landslide-filled Hershel crater.
Numerous
rounded and worn-out craters, craters within other craters and long
grooves
reminiscent of those seen on asteroids are also seen in the new images.
The
new Mimas images are available at http://saturn.jpl.nasa.gov.
All teams and offices participated today in a Cassini/NASA quarterly
review.
The Titan Orbiter Science Team hosted a Preview Meeting covering the
Titan
T6, T7, & T8 encounters. The meeting was open to anyone on the flight
team
who was interested in a preview of the science objectives and
activities for
these three flybys.
Monday, August 08 (DOY 220):
Uplink Operations sent commands to the spacecraft for Visual and
Infrared
Mapping Spectrometer (VIMS) Instrument Expanded Block files, and for a
Cosmic Dust Analyzer decontamination activity that will execute on
Friday.
The Composite Infrared Spectrometer (CIRS) and Ultraviolet Imaging
Spectrograph (UVIS) instrument teams have now delivered 100 percent of
their
archive data from launch through September 2004 to the Planetary Data
System
(PDS)
The second archive delivery on October 1, 2005 will contain data
collected
from October 2004 to December 2004. The Magnetospheric Imaging
Instrument
team has already submitted their data for this period, and it has been
accepted by PDS.
Tuesday, August 09 (DOY 221):
A kick-off meeting was held today for the DOY 227 Live Inertial Vector
Propagator (IVP) update process. A Go/No Go meeting will be held
tomorrow.
UPDATE: At the Go / No-Go meeting it was determined that the original
satellite and spacecraft ephemeris information used in planning the
observation was still very accurate, and the update to the pointing was
not
necessary.
OK. So what is all this about Live IVP updates, OD solutions,
pointing,
etc. that you keep hearing about? Initial development for a sequence
may
occur years before it is time to finally dust it off, and execute it
on-board the spacecraft. In early development the Science community
will
identify satellites they wish to observe, but at the time, the exact
details
of where to point the spacecraft are not known. There is too much
uncertainty at that time to accurately predict where the satellite is
going
to be. It requires both the Navigation team's understanding of where
the
spacecraft is, and our knowledge of the location of the satellites in
order
to ensure accurate pointing. Things change over time, hence the
uncertainty
at the time of sequence development.
To ensure that the satellite data will be acquired when the sequence
finally
executes, the concept of live movable blocks and vector updates was
developed. Basically, for a limited number of observations, spacecraft
pointing for specific targets will be analyzed, and a small portion of
the
sequence modified to ensure we are looking in the right place. The
vectors
that are being updated are superceded - updated - as part of the live
update
process, thus providing accurate pointing to the satellites. Oh, and
this
all happens while the sequence is already executing. That is why it is
called a "live" update.
If changes to the spacecraft trajectory based on the Orbit Trim
Maneuvers
(OTM) leave us with the pointing necessary to acquire the satellites,
the
Live IVP update process ends at the No/Go meeting.
Wednesday, August 10 (DOY 222)
Orbit trim maneuver #27 (OTM-27), the "Titan 6 targeting" maneuver, was
successfully completed on the spacecraft. The main engine burn began
at
07:44 am PDT. A "quick look" immediately after the maneuver showed the
burn
duration was 15.5 sec long, giving a delta-V of 2.4 m/s. AACS,
Navigation,
Propulsion, Thermal, Power, and Fault Protection teams all reported
nominal
performance after the event.
Science activities this week included CIRS' continued monitoring of the
F-Ring as well as mapping of a region just south of Saturn's equator to
determine the local temperatures of the upper troposphere and
tropopause.
The Imaging Science Subsystem (ISS) took images of Pandora, Janus,
Helene,
Telesto, Methone, Prometheus, Epimetheus, and Pan for the purpose of
better
determining the orbits of these minor satellites.
The Magnetospheric and Plasma Science (MAPS) instruments conducted a
magnetospheric boundary campaign looking in the corotation direction.
The VIMS instrument carried out a regional aurora map, and as part of
instrument calibration observed Fomalhaut, a bright star with an
unexpected
amount of infrared radiation from the disk around it. UVIS also
performed
instrument calibration by observing Alpha Eri, the ninth brightest star
in
the sky.
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.