cassini tour selection
DESCRIPTION
Cassini Tour Selection. Dr. Kevin R. Grazier IS/SPE With Significant Viewgraph Assistance By: Linda Spilker Cassini Deputy Project Scientist July 26, 2005. History. Tour 89-01 was discussed in the Cassini Announcement of Opportunity (AO) - PowerPoint PPT PresentationTRANSCRIPT
Cassini Tour SelectionCassini Tour SelectionDr. Kevin R. GrazierDr. Kevin R. Grazier
IS/SPEIS/SPE
With Significant Viewgraph Assistance By:With Significant Viewgraph Assistance By:Linda SpilkerLinda Spilker
Cassini Deputy Project ScientistCassini Deputy Project Scientist
July 26, 2005July 26, 2005
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HistoryHistory
Tour 89-01 was discussed in the Cassini Tour 89-01 was discussed in the Cassini Announcement of Opportunity (AO) Announcement of Opportunity (AO)
Discussions about creating a “new tour” began Discussions about creating a “new tour” began at very first PSG meeting (in December, 1990)at very first PSG meeting (in December, 1990)
Tour 92-01 was created after Cassini descope.Tour 92-01 was created after Cassini descope.
Very Galileo-like in its character.Very Galileo-like in its character.– mostly updated tour 89-01 for new Cassini arrival datemostly updated tour 89-01 for new Cassini arrival date
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Tour 92-01Tour 92-01
Characteristics of 92-01Characteristics of 92-01– 63 Orbits63 Orbits– 33 Titan flybys33 Titan flybys
12 inbound, 21 outbound, 10 solar/earth 12 inbound, 21 outbound, 10 solar/earth occulationsocculations
– 4 targeted icy satellite flybys: Enceladus, 4 targeted icy satellite flybys: Enceladus, Dione, Rhea, IapetusDione, Rhea, Iapetus
– 12 non-targeted flybys (d<50,000 km)12 non-targeted flybys (d<50,000 km)– Saturn/ring occultations: 5 earth and sun Saturn/ring occultations: 5 earth and sun
during first 2 occultation sequencesduring first 2 occultation sequences
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Tour Trade StudyTour Trade StudyPSG and Project agreed to a tour design trade PSG and Project agreed to a tour design trade study, scheduled between 1993 and 1996study, scheduled between 1993 and 1996Discipline Working Groups (Atmospheres, Discipline Working Groups (Atmospheres, MAPS, Satellites, Rings) developed a list of tour MAPS, Satellites, Rings) developed a list of tour geometry objectives and guidelinesgeometry objectives and guidelines– DWG tour priorities generated over several PSG DWG tour priorities generated over several PSG
meetingsmeetings– Finalized by DWGs at ESTEC PSG in May 1995Finalized by DWGs at ESTEC PSG in May 1995
Tour design tool (STOCK) provided to teamsTour design tool (STOCK) provided to teams– With software and excel spreadsheets Cassini With software and excel spreadsheets Cassini
scientists could design a Titan-only tourscientists could design a Titan-only tour
New orbit rotation technique identified (Titan 180 New orbit rotation technique identified (Titan 180 transfer)transfer)
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Tour Design ConsiderationsTour Design ConsiderationsTitan flyby strategy Titan flyby strategy Tour redesign implications of change in minimum altitude, Tour redesign implications of change in minimum altitude, number of flybys and occultationsnumber of flybys and occultationsExtent of CCW rotation at beginning of tourExtent of CCW rotation at beginning of tourNumber of moderately inclined (20-50 deg) orbits and Number of moderately inclined (20-50 deg) orbits and location during tourlocation during tourExtent of CW rotation toward magnetotailExtent of CW rotation toward magnetotailMaximum value of high inclination orbitsMaximum value of high inclination orbitsSaturn and Rings sun/earth occultation geometry strategySaturn and Rings sun/earth occultation geometry strategyIcy satellite flyby strategy for given tour Icy satellite flyby strategy for given tour rotation/inclination profilerotation/inclination profileTour strategy relative to horseshoe/tadpole trapped Tour strategy relative to horseshoe/tadpole trapped particle risk regionsparticle risk regionsGround system requirementsGround system requirements
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Selecting a TourSelecting a Tour
Orbiter workshop held in July, 1995Orbiter workshop held in July, 1995– 3 IS-led interdisciplinary teams evaluated 8 3 IS-led interdisciplinary teams evaluated 8
classes of tours (38 Titan-only tours)classes of tours (38 Titan-only tours)– Identified driving requirements and suggested Identified driving requirements and suggested
possible compromise tourspossible compromise tours
At end of tour design trade study, 17 Titan-only At end of tour design trade study, 17 Titan-only tours (T1 – T17) were available for further study tours (T1 – T17) were available for further study
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Some Tours Looked Rather Some Tours Looked Rather FamiliarFamiliar
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Others…. Didn’tOthers…. Didn’t
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Selecting a TourSelecting a Tour
At 8/96 PSG, added one class of tour for further At 8/96 PSG, added one class of tour for further study– T18study– T18Three tours quickly emerged as favored:Three tours quickly emerged as favored:
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T2T2
Quickly eliminated largely because of low science return.Quickly eliminated largely because of low science return.
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T9T9
LOVED by MAPS, Rings, Titan (two 180 transfers; 51 Titan flybys)!LOVED by MAPS, Rings, Titan (two 180 transfers; 51 Titan flybys)!Too difficult operationally (too many consecutive 16-day orbits)Too difficult operationally (too many consecutive 16-day orbits)
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The Winner Is: T18The Winner Is: T18
At 3/99 PSG selected T18-1 as final tourAt 3/99 PSG selected T18-1 as final tourLess science return than T9-1Less science return than T9-1Still difficult operationally, but we decided to “bite the bullet”.Still difficult operationally, but we decided to “bite the bullet”.Since T18-1, there have been 4 major revisions and at least 14 minor.Since T18-1, there have been 4 major revisions and at least 14 minor.
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Current Reference TourCurrent Reference Tour
74 Orbits74 Orbits
45 Titan flybys45 Titan flybys
8 targeted icy satellite flybys: Phoebe, 8 targeted icy satellite flybys: Phoebe, Enceladus (3), Dione, Rhea, Hyperion, IapetusEnceladus (3), Dione, Rhea, Hyperion, Iapetus
~30 non-targeted flybys (d < 100,000 km)~30 non-targeted flybys (d < 100,000 km)
Many Saturn/ring occultation opportunitiesMany Saturn/ring occultation opportunities– Early, middle and late in tourEarly, middle and late in tour
One Titan 180 transferOne Titan 180 transfer
One high inclination sequence at end of tourOne high inclination sequence at end of tour
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Our Pre-launch GoalsOur Pre-launch Goals
Scan Platform Working Group: 11/91Scan Platform Working Group: 11/91– Sequencing process Sequencing process must start earlymust start early, before , before
launch, if possiblelaunch, if possible– Tour fully designed before SOI (minimizes Tour fully designed before SOI (minimizes
impact of burnout, divorce, suicide, murder, impact of burnout, divorce, suicide, murder, etc. during tour)etc. during tour)
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Cassini Tour T18-5Cassini Tour T18-5Looking down from Saturn’s North PoleOuter dotted circle: Orbit of IapetusInner dotted circle: Orbit of TitanSun along +X Axis – Plot shows phase
Looking in Saturn’s Ring PlaneExcursions in inclination different from Galileo
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-5Orbit Insertion and Huygens MissionOrbit Insertion and Huygens Mission
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-5 Huygens Mission – Rev B Probe ReleaseHuygens Mission – Rev B Probe Release
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-5 Huygens Mission – Rev B Probe MissionHuygens Mission – Rev B Probe Mission
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-52005 FEB 15 to 2005 SEP 07 2005 FEB 15 to 2005 SEP 07
Mid-Rev 3 to Mid-Rev 14Mid-Rev 3 to Mid-Rev 14 Occultation SequencesOccultation Sequences
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-52005 FEB 15 to 2005 SEP 07 2005 FEB 15 to 2005 SEP 07
Mid-Rev 3 to Mid-Rev 14Mid-Rev 3 to Mid-Rev 14 Occultation SequencesOccultation Sequences
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-52005 SEP 07 to 2006 JUL 22 2005 SEP 07 to 2006 JUL 22 Mid-Rev 14 to Mid-Rev 26 Mid-Rev 14 to Mid-Rev 26
Magnetotail and Icy SatellitesMagnetotail and Icy Satellites
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-52005 SEP 07 to 2006 JUL 22 2005 SEP 07 to 2006 JUL 22 Mid-Rev 14 to Mid-Rev 26 Mid-Rev 14 to Mid-Rev 26
Magnetotail and Icy SatellitesMagnetotail and Icy Satellites
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CASSINI TOUR T18-5CASSINI TOUR T18-52006 JUL 22 to 2007 JUN 30 2006 JUL 22 to 2007 JUN 30 Mid-Rev 26 to Mid-Rev 47 Mid-Rev 26 to Mid-Rev 47
180 Transfer: Rings and MAPS180 Transfer: Rings and MAPS
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-52006 JUL 22 to 2007 JUN 30 2006 JUL 22 to 2007 JUN 30 Mid-Rev 26 to Mid-Rev 47 Mid-Rev 26 to Mid-Rev 47
180 Transfer: Rings and MAPS180 Transfer: Rings and MAPS
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CASSINI TOUR T18-5CASSINI TOUR T18-52007 JUN 30 to 2007 AUG 31 2007 JUN 30 to 2007 AUG 31
Mid-Rev 47 to Mid-Rev 49 Mid-Rev 47 to Mid-Rev 49 Iapetus Flyby Preparation/Icy SatellitesIapetus Flyby Preparation/Icy Satellites
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CASSINI TOUR T18-5CASSINI TOUR T18-52007 AUG 09 to 2007 SEP 142007 AUG 09 to 2007 SEP 14
Rev 49 Rev 49 Titan Gravity Assist and Iapetus FlybyTitan Gravity Assist and Iapetus Flyby
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CASSINI TOUR T18-5CASSINI TOUR T18-52007 AUG 09 to 2007 SEP 142007 AUG 09 to 2007 SEP 14
Rev 49 Rev 49 Titan Gravity Assist and Iapetus FlybyTitan Gravity Assist and Iapetus Flyby
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CASSINI TOUR T18-5CASSINI TOUR T18-52007 AUG 31 to 2008 JUL 01 2007 AUG 31 to 2008 JUL 01
Mid-Rev 49 to EOMMid-Rev 49 to EOM High Inclination Revs: Rings and MAPS High Inclination Revs: Rings and MAPS
All units in Rs
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CASSINI TOUR T18-5CASSINI TOUR T18-52007 AUG 31 to 2008 JUL 01 2007 AUG 31 to 2008 JUL 01
Mid-Rev 49 to EOMMid-Rev 49 to EOM High Inclination Revs: Rings and MAPS High Inclination Revs: Rings and MAPS
