Cassini Significant Events
01/28/09 - 02/03/09
The most recent spacecraft telemetry was acquired on Feb. 3 from the
Deep Space Network tracking complex at Goldstone, California. The
Cassini spacecraft is in an excellent state of health. 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.
01/28/09 - 02/03/09
The most recent spacecraft telemetry was acquired on Feb. 3 from the
Deep Space Network tracking complex at Goldstone, California. The
Cassini spacecraft is in an excellent state of health. 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, Jan. 28 (DOY 028):
An encounter strategy meeting was held today to cover the period
between Feb. 7 and Mar. 27, Titan flybys T50 and T51, and maneuvers
182-184.
Thursday, Jan. 29 (DOY 029):
Today at the Executive Session of the Cassini Project Science Group
meeting, a tour was selected from among four candidates to be part of
a proposal to be made to NASA next week for a follow-on mission after
the current extended Cassini mission is complete.
Friday, Jan. 30 (DOY 030):
An analysis published in the journal Geophysical Research Letters of
recent pictures of Titan's south polar region reveals new lake
features not seen in images of the same region
taken a year earlier. The presence of extensive cloud systems covering
the area in the intervening year suggests that the new lakes could be
the result of a large rainstorm and that some lakes may thus owe their
presence, size and distribution across Titan's surface to the moon's
weather and changing seasons. For more information on this article
link to: http://saturn.jpl.nasa.gov/news/newsreleases/20090129Titan/
and http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=3402
Monday, Feb. 2 (DOY 033):
A non-targeted flyby of Rhea occurred today.
Science Planning (SP) hosted a kick-off meeting today for the S52
Science Operations Plan (SOP) process. The SOP process is intended
to yield a conflict-free sequence, including both science and
engineering activities, down to the command level. Cassini teams
participating in this process include: the Project Science Group,
Instrument Teams, SP, the Spacecraft Office, Mission Planning, Uplink
Operations, the Instrument Operations Team, and Navigation. Outputs
from this process are an integrated conflict-free time-ordered listing
of all science observations, supporting engineering events to satisfy
mission objectives, a constraint-checked pointing profile, and data
volume allocations for the science observations contained in the
plan. At the end of this process, all products are turned over to
Uplink Operations for the final sequence development process along
with any liens and actions remaining unresolved.
Today a Cassini-Huygens Mission Status Report was published to
the Cassini web site: http://saturn.jpl.nasa.gov/news/newsreleases/20090202statusreport/
The story reported on the project's decision to swap from the Reaction
Control Subsystem thruster branch A to branch B. To give you a bit of
the technical information:
Chamber pressure roughness, a measure of efficiency for thrusters, has
been increasing on thrusters Z3A and Z4A, as shown in telemetry data
and as evidenced in the underburn at maneuver-169. Small variations
in chamber pressure roughness and thrust are normal for hydrazine
thrusters, but this recent increase could indicate thruster
degradation. At a Technical Interchange meeting on Jan. 22,
Lockheed Martin Space Systems, the propulsion module contractor,
Aerojet, the thruster manufacturer, and technical experts from the
Propulsion section of Division 35 recommended to the Cassini Project
that a swap be made to the backup thruster set B as soon as
practical. This recommendation has been accepted and a time frame of
March 12-18 is being worked.
The latest status from Spacecraft Operations (SCO) is that work is
continuing on planning the thruster branch swap in mid-March.
Preliminary reviews and file testing will occur in late February. In
early March an end-to-end test will occur exercising both files and
team procedures. An uplink readiness review is tentatively scheduled
An encounter strategy meeting was held today to cover the period
between Feb. 7 and Mar. 27, Titan flybys T50 and T51, and maneuvers
182-184.
Thursday, Jan. 29 (DOY 029):
Today at the Executive Session of the Cassini Project Science Group
meeting, a tour was selected from among four candidates to be part of
a proposal to be made to NASA next week for a follow-on mission after
the current extended Cassini mission is complete.
Friday, Jan. 30 (DOY 030):
An analysis published in the journal Geophysical Research Letters of
recent pictures of Titan's south polar region reveals new lake
features not seen in images of the same region
taken a year earlier. The presence of extensive cloud systems covering
the area in the intervening year suggests that the new lakes could be
the result of a large rainstorm and that some lakes may thus owe their
presence, size and distribution across Titan's surface to the moon's
weather and changing seasons. For more information on this article
link to: http://saturn.jpl.nasa.gov/news/newsreleases/20090129Titan/
and http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=3402
Monday, Feb. 2 (DOY 033):
A non-targeted flyby of Rhea occurred today.
Science Planning (SP) hosted a kick-off meeting today for the S52
Science Operations Plan (SOP) process. The SOP process is intended
to yield a conflict-free sequence, including both science and
engineering activities, down to the command level. Cassini teams
participating in this process include: the Project Science Group,
Instrument Teams, SP, the Spacecraft Office, Mission Planning, Uplink
Operations, the Instrument Operations Team, and Navigation. Outputs
from this process are an integrated conflict-free time-ordered listing
of all science observations, supporting engineering events to satisfy
mission objectives, a constraint-checked pointing profile, and data
volume allocations for the science observations contained in the
plan. At the end of this process, all products are turned over to
Uplink Operations for the final sequence development process along
with any liens and actions remaining unresolved.
Today a Cassini-Huygens Mission Status Report was published to
the Cassini web site: http://saturn.jpl.nasa.gov/news/newsreleases/20090202statusreport/
The story reported on the project's decision to swap from the Reaction
Control Subsystem thruster branch A to branch B. To give you a bit of
the technical information:
Chamber pressure roughness, a measure of efficiency for thrusters, has
been increasing on thrusters Z3A and Z4A, as shown in telemetry data
and as evidenced in the underburn at maneuver-169. Small variations
in chamber pressure roughness and thrust are normal for hydrazine
thrusters, but this recent increase could indicate thruster
degradation. At a Technical Interchange meeting on Jan. 22,
Lockheed Martin Space Systems, the propulsion module contractor,
Aerojet, the thruster manufacturer, and technical experts from the
Propulsion section of Division 35 recommended to the Cassini Project
that a swap be made to the backup thruster set B as soon as
practical. This recommendation has been accepted and a time frame of
March 12-18 is being worked.
The latest status from Spacecraft Operations (SCO) is that work is
continuing on planning the thruster branch swap in mid-March.
Preliminary reviews and file testing will occur in late February. In
early March an end-to-end test will occur exercising both files and
team procedures. An uplink readiness review is tentatively scheduled
for Mar. 6. During the actual uplink
and hardware swap, the
background sequence will be deactivated. This means that all science
and engineering activity will cease on board. Sequence leads have
contacted the instrument teams to determine what states the
instruments should be left in - off, sleep, other - when the
background sequence halts. The science data collected prior to DOY
071 will be preserved on the SSR and will be played back after the
thruster swap procedure has completed. Deactivation is currently
planned for Mar. 10. The B-branch thruster swap is planned for Mar. 12
followed by various checkout and calibration activities until the S48
background sequence is re-activated Mar. 18. The B-branch latch valve
and the B-branch catalyst bed heaters will be placed into their
correct configurations for B-branch operations before the actual swap.
Tuesday, Feb. 3 (DOY 034):
The Orbit Determination (OD) and Maneuver solutions for Orbit Trim
Maneuver (OTM)-181 are very stable and very little movement is
expected in the next few days. Without an OTM, the flyby at Titan 50
is predicted to be about 9.3 km high. The OTM has a magnitude of
about 40 mm/sec, however cancellation would save about 1.2 m/s. The
no OTM solution has been provided to science, and RADAR - potentially
the most impacted team - found it to be acceptable. SCO recommended
cancellation due to concerns related to the A-branch thrusters.
Navigation recommended and the project has concurred with the
cancelation of OTM 181.
The sequence leads for S49 reported that the Titan 51 and Titan 52
Radio Science bistatic observations would be tested in the Integrated
Test Laboratory prior to being executed. A Simulation Coordination
meeting was held today to support this activity. On Thursday the team
will review the procedures for these tests. S49 begins execution on
board the spacecraft on Mar. 26.
Activity has now begun for the fourth Live Inertial Vector Propagator
Update in S47. The update will be based on the maneuver #182 OD
solution. The OD will be published by end-of-day Monday. Execution is
planned for DOY 44-45 with vector updates for Saturn and Titan. The
schedule is very tight - there are less than two days to turn around
and process this update. The Kickoff Meeting is scheduled for Monday,
Feb. 9.
------------------------
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<http://saturn.jpl.nasa.gov/news/mailinglistsignup/>
------------------------
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<http://saturn.jpl.nasa.gov/feedback/>
------------------------
Visit the JPL Cassini home page for more information about the Cassini Project: <http://saturn.jpl.nasa.gov/>
------------------------
background sequence will be deactivated. This means that all science
and engineering activity will cease on board. Sequence leads have
contacted the instrument teams to determine what states the
instruments should be left in - off, sleep, other - when the
background sequence halts. The science data collected prior to DOY
071 will be preserved on the SSR and will be played back after the
thruster swap procedure has completed. Deactivation is currently
planned for Mar. 10. The B-branch thruster swap is planned for Mar. 12
followed by various checkout and calibration activities until the S48
background sequence is re-activated Mar. 18. The B-branch latch valve
and the B-branch catalyst bed heaters will be placed into their
correct configurations for B-branch operations before the actual swap.
Tuesday, Feb. 3 (DOY 034):
The Orbit Determination (OD) and Maneuver solutions for Orbit Trim
Maneuver (OTM)-181 are very stable and very little movement is
expected in the next few days. Without an OTM, the flyby at Titan 50
is predicted to be about 9.3 km high. The OTM has a magnitude of
about 40 mm/sec, however cancellation would save about 1.2 m/s. The
no OTM solution has been provided to science, and RADAR - potentially
the most impacted team - found it to be acceptable. SCO recommended
cancellation due to concerns related to the A-branch thrusters.
Navigation recommended and the project has concurred with the
cancelation of OTM 181.
The sequence leads for S49 reported that the Titan 51 and Titan 52
Radio Science bistatic observations would be tested in the Integrated
Test Laboratory prior to being executed. A Simulation Coordination
meeting was held today to support this activity. On Thursday the team
will review the procedures for these tests. S49 begins execution on
board the spacecraft on Mar. 26.
Activity has now begun for the fourth Live Inertial Vector Propagator
Update in S47. The update will be based on the maneuver #182 OD
solution. The OD will be published by end-of-day Monday. Execution is
planned for DOY 44-45 with vector updates for Saturn and Titan. The
schedule is very tight - there are less than two days to turn around
and process this update. The Kickoff Meeting is scheduled for Monday,
Feb. 9.
------------------------
To unsubscribe from Cassini Spacecraft Updates or to subscribe with a different email address, visit:
<http://saturn.jpl.nasa.gov/news/mailinglistsignup/>
------------------------
This email address is not monitored. For comments and questions, please contact Cassini Outreach at:
<http://saturn.jpl.nasa.gov/feedback/>
------------------------
Visit the JPL Cassini home page for more information about the Cassini Project: <http://saturn.jpl.nasa.gov/>
------------------------
