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JJet Propulsion LaboratoryCalifornia Institu te of Technology

PD 699-100, Rev NJPL D-5564, Rev N

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CASSINI PROJECT

DOCUMENT CHANGE NOTICE

TITLE: Changes to the Cassini Mission Plan

DOCUMENT TITLE: Cassini Mission Plan,

JPL D-NUMBER

PD 699-100, Rev. N

DOCUMENTCHANGE ID: Revision N

PAGE 1 OF 1

DATE: 10 May 2002

DISTRIBUTION APPROVED BY: [Include document approval authorities and document custodian]

Document Distribution

List:

Dave Seal, Mission Planning Lead Date

DESCRIPTION OF CHANGE:

This revised document reflects changes since revision M. All changes basedon the latest knowledge of mission activities and spacecraft capabilities have

been documented. Changes have been made to reflect the re-desgned ProbeMission, which has affected the SOI burn, Probe release activities, and initialtour orbits. In addition, more detail has been added to descriptions of cruisescience, SOI activities, Probe mission, and Tour activities.

list maintained byMission Planning

Custodian: Jim Frautnick

: JPL D-5564, Rev. N

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MISSION PLANTABLE OF CONTENTS

SECTION 1 IN TRODUCTION.................................................................................................. 1-11.1 Relationship to Oth er Documents ................................................................................ 1-11.2 Sched ule for Document Updates .................................................................................. 1-1

SECTION 2 MISSION OVERVIEW ......................................................................................... 2-1

2.1 Mission Synopsis .............................................................................................................2-12.2 Interplanetary Trajectory ...............................................................................................2-72.3 Tour Overview ................................................................................................................ 2-72.4 Reference tables ............................................................................................................. 2-23

SECTION 3 SCIEN CE OBJECTIVES ....................................................................................... 3-13.1 General Objectives .......................................................................................................... 3-13.2 Specific Objectives Before Saturn ................................................................................. 3-13.3 Specific Objectives at Satu rn .......................................................................................... 3-23.4 Specific Objectives at Titan ............................................................................................ 3-23.5 Specific Objectives at the Rings..................................................................................... 3-23.6 Specific Objectives at the Icy Satellites......................................................................... 3-2

3.7 Specific Objectives at the Saturn Magnetosphere ...................................................... 3-23.8 Orbiter Science Instru ments .......................................................................................... 3-3

3.8.1 Cassin i Plasm a Spectrometer (CAPS) .................................................................. 3-33.8.2 Cosmic Du st Analyzer (CDA)............................................................................... 3-33.8.3 Com posite Infrar ed Spectrom eter (CIRS)............................................................ 3-43.8.4 Ion and N eutral Mass Spectrom eter (INMS) ...................................................... 3-53.8.5 Imaging science subsystem (ISS) .......................................................................... 3-53.8.5 Magnetometer (MAG) ............................................................................................ 3-53.8.6 Rad io Science Subsystem (RSS) ............................................................................3-63.8.7 Ultraviolet Imaging Spectrograph (UVIS)........................................................... 3-73.8.8 Visible an d Infrared Map ping Spectrometer (VIMS) ........................................ 3-83.8.10 RADAR ..................................................................................................................... 3-83.8.11 Radio and Plasm a Wave Spectrom eter (RPWS)................................................. 3-83.8.12 Magnetospher ic Imaging Instrument (MIMI) .................................................... 3-9

3.9 Huygens Probe Instruments ..........................................................................................3-93.9.1 Aerosol Collector Pyrolyzer (ACP) ...................................................................... 3-93.9.2 Gas Chromatograph and Mass Spectrometer (GCMS) ..................................... 3-93.9.3 Descent Imager and Spectra l Radiometer (DISR) ............................................ 3-103.9.4 Dop pler Wind Experiment (DWE) ..................................................................... 3-103.9.5 Huygens Atm osph eric Stru cture Instru men t (HASI)...................................... 3-103.9.6 Surface Science Package (SSP)............................................................................. 3-11

SECTIO N 4 FLIGHT SYSTEM DESCRIPTIO NS .................................................................. 4-14.1 Launch Vehicle Descrip tion .......................................................................................... 4-14.2 Orbiter Descrip tion .........................................................................................................4-2

4.2.1 S/ C Att itude Definit ion ......................................................................................... 4-34.2.2 Attitude Com manding ...........................................................................................4-44.2.3 Inert ial Vector Propagation ................................................................................... 4-54.2.4 Stru ctu re Subsystem ...............................................................................................4-74.2.5 Radio Frequ ency Subsystem ................................................................................. 4-74.2.6 Pow er and Pyrotechnics Subsystem ..................................................................... 4-74.2.7 Com mand and Data Subsystem ........................................................................... 4-74.2.8 Att itude and Articu lation Control Subsystem .................................................... 4-9

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4.2.9 Cabling Subsystem................................................................................................4-124.2.10 Propulsion Module Subsystem ........................................................................... 4-124.2.11 Temperature Con trol Subsystem ........................................................................ 4-154.2.12 Mechanical Devices Subsystem .......................................................................... 4-164.2.13 Electronic Packaging Subsystem ........................................................................ 4-164.2.14 Solid State Recorder Subsystem .......................................................................... 4-164.2.15 Anten na Subsystem .............................................................................................. 4-164.2.16 Science Instruments .............................................................................................. 4-17

4.2.17 Orbiter Consumable Budgets .............................................................................. 4-174.3 The Huygens Probe System......................................................................................... 4-17

4.3.1 Entry Subsystem ....................................................................................................4-174.3.2 Inn er Stru ctu re Subsystem ................................................................................... 4-214.3.3 Therm al Con trol Subsystem ................................................................................ 4-214-4.3.4Electrical Power Subsystem ................................................................................. 4-214.3.5 Command and Data Management Subsystem ................................................. 4-234.3.6 Probe Data Relay Subsystem ............................................................................... 4-234.3.7 Huygen s science Instru mentation ...................................................................... 4-23

SECTIO N 5 OPERATIO NS STRATEG IES ............................................................................. 5-15.1 Op erations Con cepts ...................................................................................................... 5-1

5.1.1 ON -BOARD opera tion s.......................................................................................... 5-15.1.2 Ground plann ing & operations............................................................................. 5-25.1.3 Data distr ibu tion ..................................................................................................... 5-35.1.4 Activ ity Overview ................................................................................................... 5-4

5.2 Telecom munications ....................................................................................................... 5-45.2.1 Anten na Switches ....................................................................................................5-55.2.2 Up link .......................................................................................................................5-55.2.3 Bits to grou nd .......................................................................................................... 5-5

5.3 data storage ...................................................................................................................... 5-85.3.1 Partitionin g ..............................................................................................................5-85.3.2 Data policing.......................................................................................................... 5-135.3.3 Carryover ............................................................................................................... 5-145.3.4 DSN locku p ............................................................................................................ 5-14

5.4 attitude control .............................................................................................................. 5-145.4.1 Spacecraft ar ticu lation .......................................................................................... 5-185.4.2 Target Motion Com pensation ............................................................................. 5-185.4.3 Titan atmosp heric mod el ..................................................................................... 5-195.4.4 Min imum Flyby Altitu des ................................................................................... 5-19

5.5 Navigation ...................................................................................................................... 5-205.5.1 Tracking requ irements ......................................................................................... 5-205.5.2 Maneuvers .............................................................................................................. 5-225.5.3 Encou nter redesign ............................................................................................... 5-23

5.6 Environm ental hazard s & control ..............................................................................5-245.6.1 Rad iation ................................................................................................................ 5-245.6.2 Thermal control and sun Exposu re .................................................................... 5-245.6.3 Debris ...................................................................................................................... 5-26

5.7 period ic activ ities .......................................................................................................... 5-265.7.1 Engineerin g Maintenance .................................................................................... 5-275.7.2 Huygen s Probe Checkouts .................................................................................. 5-275.7.3 Periodic Instru ment Main tenance ...................................................................... 5-30

SECTION 6: LAUN CH AND CRUISE ACTIVITIES.............................................................. 6-16.1 Lau nch Phase ................................................................................................................... 6-1

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6.1.1 Lau nch Sequence subp hase ................................................................................... 6-16.1.2 TCM 1 Subphase ..................................................................................................... 6-4

6.2 Inn er Cruise Phase .......................................................................................................... 6-66.2.1 Venus 1 Flyby Subp hase ........................................................................................ 6-96.2.2 Instru ment Checkout Subp hase............................................................................ 6-96.2.3 Venus 2 - Earth Subp hase .................................................................................... 6-10

6.3 Ou ter Cruise Phase ...................................................................................................... 6-206.3.1 Spacecraft HGA Checkou t subphase ................................................................ 6-22

6.3.2 Instru ment Checkout-2 Subphase ...................................................................... 6-226.3.3 Jupiter Subphase ................................................................................................... 6-236.3.4 Qu iet Cruise Subphase ......................................................................................... 6-26

6.4 Science Cru ise Phase ..................................................................................................... 6-276.4.1 Space Science Subphase ....................................................................................... 6-276.4.2 Ap proach Science Subphase............................................................................... 6-28

SECTION 7: SATURN AND TO UR ACTIVITIES.................................................................. 7-17.1 Saturn approach and phoebe ........................................................................................ 7-17.2 Satu rn Orbit Insert ion..................................................................................................... 7-2

7.2.1 Overview ..................................................................................................................7-27.2.2 SOI Trajectory .......................................................................................................... 7-4

7.2.3 SOI Critical Sequence Overv iew ........................................................................... 7-87.2.4 SOI Burn ...................................................................................................................7-97.2.5 Attitude Con trol Strategy .................................................................................... 7-107.2.6 SSR Strategy ........................................................................................................... 7-117.2.7 Telecom Strategy ................................................................................................... 7-117.2.8 Science Strategy ..................................................................................................... 7-12

7.3 Init ial Orbit ..................................................................................................................... 7-137.4 The Huygen s Probe Mission ....................................................................................... 7-13

7.4.1 Probe Separation ................................................................................................... 7-157.4.2 Probe Relay ............................................................................................................ 7-19

7.5 Op tical Rem ote Sensing Encounters .......................................................................... 7-257.6 RADAR encounters ...................................................................................................... 7-267.7 Rad io Science encounters............................................................................................. 7-29

SECTION 8: OPERATIONAL MO DES, GUID ELINES AND CON STRAINTS, ANDCO NTROLLED SCEN ARIO TIMELINES................................................................................ 8-1

8.1 Mission Planning Fram ework ....................................................................................... 8-18.1.1 Op erational Mod e Definition ................................................................................ 8-18.1.2 Sequence Con structs Defin ition ............................................................................8-18.1.3 Requirem ents on the Design of Op erationa l Mod es.......................................... 8-28.1.4 Requirem ents on the Design of Mod ules ............................................................ 8-3

8.2 Mission Design Gu idelines & Constraints Definition ............................................. 8-108.3 Mission Design Guidelines and Constraint s............................................................. 8-10

8.3.1 Op erational Mod es and Sequ ence Constructs .................................................. 8-108.3.2 Sequence Develop ment ........................................................................................ 8-118.3.3 Spacecraft Point ing ............................................................................................... 8-148.3.4 Telecom munications ............................................................................................. 8-148.3.5 Man agem ent of On-Board Data .......................................................................... 8-168.3.6 Pre-Satu rn Science Activ ities ............................................................................... 8-178.3.7 Satu rn Tour & SOI ................................................................................................ 8-178.3.8 Miscellaneou s ........................................................................................................ 8-18

8.4 Controlled Scenario Timelines .................................................................................... 8-19

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ECR CHAN GE LOGGUID ELINES & CON STRAINTS HISTO RY

APPENDICIESA REQ UIREM EN TS CO MPLIAN CEB SATURN IAN SYSTEM D ESCRIPTIO NK SATURN MYTHOLOGYL CASSIN I AN D H UYG EN S, TH E SCIEN TISTS

ACRON YM LIST

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1-1

SECTION 1 INTRODUCTION

The Mission Plan is the pr incipal reference for high level descriptions of the Cassini mission. Itdocum ents the interp lanetary cruise and Saturn tou r trajectories; high level spacecraft andactivity designs; operational strategies and options; and guid elines and constraints for m issionoperations. It is not w ithin the scope of the Mission Plan to illustrate any one sequence to thegranu larity of second s or m inutes, or describe ind ividual states of spacecraft comp onents.Neither is it to d escribe high level project p olicy. The Mission Plan is the interm ediary betw een

the p roject requ irements -- and their associated documents -- and the detailed missionsequences, along with their associated d ocum ents.

This plan serves to guide the d evelopment of detailed event timelines from before launchthrou gh end of mission and will evolve throu ghou t the m ission as a living document. Section 2provides a brief overview of the Cassini mission, including the sp acecraft trajectory d uringcruise and tou r, and a sum mary of the main events d uring th e flight. Section 3 describes thescience objectives of the mission. Section 4 describes the spacecraft, probe, instru men t, andlaunch vehicle systems. Section 5 illustrates the p rimary operational strategies developed orled by th e mission planners to operate the spacecraft and solve some of the m ore difficultproblems which cross systems. Section 6 describes the details of activities during launch andinterplanetary cruise, wh ereas section 7 covers the tour ph ase. Section 8 docum ents m ission-level guidelines and constraints, operational modes, and timelines for crucial periods, and is

un der project level change control. Changes to Section 8 requ ire engineering change requests(ECRs) and the ap proval of the project change control board , whereas changes to theremaining sections require ap prova l of the Mission Plann ing office. Append ices are includ edas reference material.

1.1 RELATIONSHIP TO OTHER DOCUMENTS

The Mission Plan imp lements p roject p olicy docum ented in the Project Policies andRequirements Document (699-004). Other resources listed below are relevant to many sectionsof the Mission Plan and are referred to where possible so as not to dup licate information orrequire parallel up da tes shou ld information change.

Resource Document Number

Project Policies and Requirements 699-004Orbiter Functional Requirements 699-205

Navigation Plan 699-101

Consumables Report 699-523

Post-Jupiter Scoping Package (Internal memorandum)

Risk Management Plan 699-015

1.2 SCHEDULE FOR DOCUMENT UPDATES

Past Mission Plan releases have been as follows:

Version Release Version Release Version Release

Initial Ju l 1988 F Apr 1995 J Jul 1999

A May 1990 G Feb 1997 K Jan 2000B Mar 1993 G.1 Jun 1997 L Jul 2000

C Aug 1993 G.2 Feb 1998 M Jun 2001

D Feb 1994 H Mar 1998 N May 2002

E Sep 1994 I Dec 1998

This version docum ents the state of the mission as und erstood as of the release date. Due tospace limitations, discussion of unu sed m ission op tions and past op erational strategies havebeen removed wh ere they are no longer relevant, and rep laced w ith as-flown descriptions.Refer to previous versions of the Mission Plan for reconstruction of these options.

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2-1

SECTION 2 MISSION OVERVIEW

2.1 MISSION SYNOPSIS

The Cassini spacecraft is a combined Saturn orbiter and Titan atm ospheric probe (to bedelivered on the first or second flyby of Titan). It is a three-axis stabilized spacecraft equipp edfor 27 diverse science investigations w ith 12 orbiter and 6 Hu ygens p robe instrum ents, onehigh gain an d two low gain an tennas, three Radioisotope Thermal Generators (RTGs) forpow er, main engines, attitud e thrusters, and reaction w heels.

Cassini w as successfully launched on 15 October 1997 using the Titan IV/ Centaur launchvehicle with Solid Rocket Motor Up grade (SRMU) strap-ons and a Centau r u pp er stage. Thespacecraft is flying a 6.7-year Venu s-Venu s-Earth -Jup iter Gravity Assist (VVEJGA) tra jectoryto Saturn, du ring w hich cruise science is planned to checkout, calibrate, and maintain theinstrum ents as well as characterize the instru ments an d perform limited science observations.Cru ise science is limited by flight software available on the spacecraft as well as cost,scheduling and workforce constraints. Limited science data collection occurred du ring theVenu s flybys and science and calibration occurred du ring the Earth flyby. As the spacecraftapp roached Jupiter, science activities picked up as Jup iter observations served as p reparationfor the four-year tour of the Saturnian system.

During m ost of the early portion of cruise, the High Gain Antenna (HGA) was requ ired to

shield m ost of the spacecraft from the Sun and only low-rate comm unications via thespacecrafts Low Gain Antennas (LGAs) was possible. Six months after the Earth flyby, thespacecraft was far enough from the Sun to orient the H igh Gain Antenna (HGA) to Earthenabling mu ch faster comm un ications. Following the Jup iter flyby, the spacecraft attemp ts todetect gravitational waves using its Ka-band and X-band rad io equipment. Instrum entcalibrations, checkout, and other tour p repara tions are also conducted d uring th e cru isebetween Jupiter and Saturn. In the six months p receding its arrival at Saturn, the spacecraftwill conduct more intensive science activities, including observations of Phoebe immediatelybefore arrival on 11 June 2004.

During Satu rn Orbit Insertion (SOI) on 1 July 2004, the sp acecraft makes its closest approach tothe p lanets sur face du ring th e entire mission at an altitude of only 0.3 Satu rn rad ii (18,000

km). Due to this unique opp ortun ity, the app roximately 100-minu te SOI burn requ ired toplace Cassini in orbit arou nd Saturn executes sooner than its optimal point centered arou ndperiapsis, and instead end s at p eriapsis, allowing science observations immediately afterclosest app roach.

At the third targeted Titan flyby, the ESA Hu ygens probe d escends through the atm osphere ofTitan to its sur face. This probe is released from the orbiter 21 to 22 days before the first Titanflyby. Eleven days after p robe release, the orbiter performs a d eflection maneuver to p laceitself on the prop er trajectory for the encounter. The probe flies d irectly into Titan'satmosp here, where it relays data to the orbiter for up to 2.5 hours du ring its descent to thesurface.

The orbiter then continues on a tour of the Saturnian system, includ ing mu ltiple close Titan

flybys for gravity assist and science acquisition. The Titan flybys and Satu rn orbits have beendesigned to maximize science coverage wh ile meeting resource and op erations limitations.Targeted and non-targeted flybys of selected icy satellites have also been included todeterm ine icy satellite surface compositions and geologic histories. Cassinis orbital inclinationvaries widely to investigate the field, par ticle, and wave environmen t at high latitud es,includ ing the hyp othesized source of the unique Saturn k ilometric radiation. High inclinationsalso permit high-latitude Saturn radio occultations, viewing of Saturn p olar regions, and morenear ly vertical viewing of Satu rn 's rings. The baseline mission ends in mid -2008, for a totalmission d ur ation of 10.7 years.

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CASSINI MISSION EVENT SUMMARY

Name Epoch DOY DOW Comment

Launch 1997-Oct-15 288 Wed C3 = 16.6 km2/sec2

APHELION 1997-Nov-06 310 Thu Sun range = 1.01 AU

TCM-1 1997-Nov-09 313 Sun V = 2.7 m/sec on MEo Conjunction 1998-Feb-09 040 Mon Inferior conjunctionTCM-2 1998-Feb-25 056 Wed V = 0.2 m/sec on RCSPERIHELION 1998-Mar-27 086 Fri Sun range = 0.67 AU

(TCM-3) 1998-Apr-08 098 Wed Canceled

Venus flyby 1998-Apr-26 116 Sun Altitude = 284 km; Speed = 11.8 km/sec

(TCM-4) 1998-May-14 134 Thu Canceled

DSM 1998-Dec-03 337 Thu V = 450 m/secDSM-5 1998-Dec-03 337 Thu V = 450.2 m/sec on MEAPHELION 1998-Dec-07 341 Mon Sun range = 1.58 AU

HGA 1998-Dec-28 362 Mon 25 day checkout period

o Opposition 1999-Jan-09 009 Sat

LGA 1999-Jan-21 021 Thu Probe thermal constraints restrict HGA usage

TCM-6 1999-Feb-04 035 Thu V = 11.6 m/sec on METCM-7 1999-May-18 138 Tue V = 0.2 m/sec on RCS(TCM-8) 1999-Jun-03 154 Thu Canceled

Venus flyby 1999-Jun-24 175 Thu Altitude = 603 km; Speed = 13.6 km/sec

PERIHELION 1999-Jun-29 180 Tue Sun range = 0.72 AU

TCM-9 1999-Jul-06 187 Tue V = 43.5 m/sec on METCM-10 1999-Jul-19 200 Mon V = 5.1 m/sec on METCM-11 1999-Aug-02 214 Mon V = 36.3 m/sec on METCM-12 1999-Aug-11 223 Wed V = 12.3 m/sec on MEo Conjunction 1999-Aug-17 229 Tue Inferior conjunction

Earth flyby 1999-Aug-18 230 Wed Altitude = 1175 km; Speed = 19.0 km/sec

TCM-13 1999-Aug-31 243 Tue V = 6.7 m/sec on MEo Opposition 1999-Sep-13 256 Mon

Enter Asteroid Belt 1999-Dec-11 345 Sat Sun range = 2.2 AU

HGA 2000-Feb-01 032 Tue HGA is Earth-pointed; use after this date

Exit Asteroid Belt 2000-Apr-12 103 Wed Sun range = 3.3 AU

o Conjunction 2000-May-13 134 Sat Superior Conjunction

TCM-14 2000-Jun-14 166 Wed V = 0.6 m/sec on METCM-15 2000-Sep-14 258 Thu V = 0.2 m/sec on RCSo Opposition 2000-Nov-28 333 Tue Gravity Wave Opportunity

(TCM-16) 2000-Dec-07 342 Thu Cancelled

Jupiter flyby 2000-Dec-30 365 Sat Altitude = 9,723,890 km; Speed = 11.6 km/sec

TCM-17 2001-Feb-28 059 Wed V = 1.0 m/sec on MEo Conjunction 2001-Jun-07 158 Thu Superior Conjunction

o Opposition 2001-Dec-16 350 Sun Gravity Wave Experiment - opp20 days

TCM-18 2002-Apr-03 093 Wed V = 1.2 m/sec on MEo Conjunction 2002-Jun-21 172 Fri Conjunction Experiment - conj15 days

o Opposition 2002-Dec-27 361 Fri Gravity Wave Experiment - opp20 days

TCM-19 2003-May-01 121 Thu V = 0.5 m/sec on RCSo Conjunction 2003-Jul-01 182 Tue Conjunction Experiment - conj15 days

o Opposition 2004-Jan-04 004 Sun Early Gravity Wave Experiment - Oct-Nov 2003

TCM-20 2004-May-27 148 Thu V = 35 m/sec on MEPhoebe flyby 2004-Jun-11 163 Fri Altitude = 2000 km; Speed = 6.4 km/sec

TCM-21 2004-Jun-16 168 Wed V = 5.5 m/sec on ME

TCM-22 2004-Jun-21 173 Mon Emergency TCM window if neededSOI 2004-Jul-01 183 Thu V = 633 m/seco Conjunction 2004-Jul-08 190 Thu

PRM 2004-Aug-23 236 Mon V = 391 m/secTitan A 2004-Oct-26 300 Tue Altitude = 1200 km; Speed = 6.1 km/sec

Titan B 2004-Dec-13 348 Mon Altitude = 2346 km; Speed = 6.1 km/sec

Probe Separation 2004-Dec-24 359 Fri

ODM 2004-Dec-29 364 Wed V = 21 m/secTitan C / Huygens 2005-Jan-14 014 Fri Altitude = 60,000 km; Speed = 5.4 km/sec

o Opposition 2005-Jan-13 013 Thu

EOM 2008-Jun-30 182 Mon End of 4-year tour

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Jupiter

Venu

s1

Venu

s2

Earth

Launch

0 200 400 600 800 1000 1200 1400 1600 1800 DAYS FROMLAUNCH

PHASES

DSN COVERAGE

REQUESTED(passes/week)

EVENTS

MANEUVERS

c c c c

EARTH

CONJUNCTIONOPPOSITION

POINTING

ANTENNA

c

HGA

SUN

Laun

ch

Scie

nce

On

EARTH#

HGA#

Inf Inf

PERIHELION/APHELION

A P A P

Refer to Appendix J for more information about data rate capability.*

1.02 AU 0.68 AU 1.58 AU 0.72 AU

LGA LGA

SUN

Superior Conjunction causes degradation of telemetry and radiometric tracking data.

Figure 2.1: Cassini Cruise Segment Timeline

Sup Sup Sup

DSM

HGA

SUBPHASES ICO #1

Inner Cruise Outer Cruise

Launch Sequence

TCM1Venus 1 Venus 2 - Earth Jupiter Quiet Cruise

GWEopp GWE G

Conj.Experiment

c

Indicates actual instrument checkout window.#

21

0

7

14

DOWNLINKDATA RATECAPABILITY(Ranging ON)

high

rates

NOSAJJMAMFJDNOSAJJMAMFJDNOSAJJMAMFJDNOSAJJMAMFJDNOSAJJMAMFJDN O

1997 1998 1999 2000 2001 2002

bps(log scale)

4 0

200

94 8

142 k248 k

HGATransition ICO #2

LGA HGA

22 k

82 k35 k

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CASSINI PHASES, SUBPHASES AND LOAD BOUNDARIES (CRUISE)

Start End Length

Phase Subphase Name Date DOW Date DOW (days)

Launch C0 1997-288T00:00 Wed 1997-290T00:00 Fri 2

C1 1997-290T00:00 Fri 1997-297T00:00 Fri 7

C2 1997-297T00:00 Fri 1997-304T00:00 Fri 7

C3 1997-304T00:00 Fri 1997-311T00:00 Fri 7

C4 1997-311T00:00 Fri 1997-318T00:00 Fri 7

C5 1997-318T00:00 Fri 1998-019T00:00 Mon 66

C6 1998-019T00:00 Mon 1998-075T00:00 Mon 56

C7 1998-075T00:00 Mon 1998-131T00:00 Mon 56

C8 1998-131T00:00 Mon 1998-194T00:00 Mon 63

C9 1998-194T00:00 Mon 1998-257T00:00 Mon 63

C10 1998-257T00:00 Mon 1998-320T00:00 Mon 63

C11 1998-320T00:00 Mon 1999-025T00:00 Mon 70

C12 1999-025T00:00 Mon 1999-074T00:00 Mon 49

C13 1999-074T00:00 Mon 1999-130T00:00 Mon 56

C14 1999-130T00:00 Mon 1999-193T00:00 Mon 63

C15 1999-193T00:00 Mon 1999-249T00:00 Mon 56

C16 1999-249T00:00 Mon 1999-312T00:00 Mon 63

C17 1999-312T00:00 Mon 2000-017T00:00 Mon 70

C18 2000-017T00:00 Mon 2000-066T00:00 Mon 49

C19 2000-066T00:00 Mon 2000-127T00:00 Sat 61

C20 2000-127T00:00 Sat 2000-192T00:00 Mon 65

C21 2000-192T00:00 Mon 2000-255T00:00 Mon 63

C22 2000-255T00:00 Mon 2000-310T05:25 Sun 55

C23 2000-310T05:25 Sun 2001-014T11:00 Sun 70

C24 2001-014T11:00 Sun 2001-071T09:55 Mon 57

C25 2001-071T09:55 Mon 2001-120T00:00 Mon 49

C26 2001-120T00:00 Mon 2001-190T00:00 Mon 70

C27 2001-190T00:00 Mon 2001-252T00:00 Sun 62

C28 2001-252T00:00 Sun 2001-309T00:00 Mon 57

C29 2001-309T00:00 Mon 2002-014T00:00 Mon 70

C30 2002-014T00:00 Mon 2002-070T00:00 Mon 56

C31 2002-070T00:00 Mon 2002-126T00:00 Mon 56

C32 2002-126T00:00 Mon 2002-189T00:00 Mon 63

C33 2002-189T00:00 Mon 2002-266T00:00 Mon 77

C34 2002-266T00:00 Mon 2002-336T00:00 Mon 70

C35 2002-336T00:00 Mon 2003-048T00:00 Mon 77

C36 2003-048T00:00 Mon 2003-104T00:00 Mon 56

C37 2003-104T00:00 Mon 2003-167T00:00 Mon 63

C38 2003-167T00:00 Mon 2003-223T00:00 Mon 56

C39 2003-223T00:00 Mon 2003-293T00:00 Mon 70

C40 2003-293T00:00 Mon 2004-010T00:00 Sat 82

C42 2004-010T00:00 Sat 2004-052T00:00 Sat 42

C43 2004-052T00:00 Sat 2004-094T00:00 Sat 42

C44 2004-094T00:00 Sat 2004-136T00:00 Sat 42

TCM 1Launch

Inner Cruise

Venus2-Earth

ICO-1

Venus 1

Outer Cruise

Quiet Cruise

Jupiter

ICO-2

HGA transition

Science Cruise

Approach Science

Space Science

C41 was merged with C40 for GWE.

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CASSINI PHASES AND LOAD BOUNDARIES (TOUR)*

Start End Length

PhaseName date DOW date DOW (days)

Tour S1 2004-136T00:00 Sat 2004-171T01:38 Sat 35

S2 2004-171T01:38 Sat 2004-212T23:05 Fri 42

S3 2004-212T23:05 Fri 2004-255T19:10 Sat 43S4 2004-255T19:10 Sat 2004-290T18:40 Sat 35

S5 2004-290T18:40 Sat 2004-318T16:59 Sat 28

S6 2004-318T16:59 Sat 2004-351T15:03 Thu 33

S7 2004-351T15:03 Thu 2005-022T10:38 Sat 37

S8 2005-022T10:38 Sat 2005-058T00:36 Sun 36

S9 2005-058T00:36 Sun 2005-099T05:15 Sat 41

S10 2005-099T05:15 Sat 2005-134T02:50 Sat 35

S11 2005-134T02:50 Sat 2005-169T01:34 Sat 35

S12 2005-169T01:34 Sat 2005-210T22:36 Fri 42

S13 2005-210T22:36 Fri 2005-242T21:53 Tue 32

S14 2005-242T21:53Tue

2005-281T15:57Sat

39S15 2005-281T15:57 Sat 2005-316T17:01 Sat 35

S16 2005-316T17:01 Sat 2005-351T14:21 Sat 35

S17 2005-351T14:21 Sat 2006-028T11:23 Sat 42

S18 2006-028T11:23 Sat 2006-070T00:35 Sat 42

S19 2006-070T00:35 Sat 2006-112T05:15 Sat 42

S20 2006-112T05:15 Sat 2006-154T02:39 Sat 42

S21 2006-154T02:39 Sat 2006-196T00:06 Sat 42

S22 2006-196T00:06 Sat 2006-230T22:06 Fri 35

S23 2006-230T22:06 Fri 2006-269T19:53 Tue 39

S24 2006-269T19:53 Tue 2006-295T18:26 Sun 26

S25 2006-295T18:26 Sun 2006-328T16:30 Fri 33

S26 2006-328T16:30 Fri 2007-005T13:50 Fri 42

S27 2007-005T13:50 Fri 2007-048T10:52 Sat 43

S28 2007-048T10:52 Sat 2007-088T08:04 Thu 40

S29 2007-088T08:04 Thu 2007-124T22:00 Fri 37

S30 2007-124T22:00 Fri 2007-162T03:10 Mon 37

S31 2007-162T03:10 Mon 2007-195T01:06 Sat 33

S32 2007-195T01:06 Sat 2007-223T23:20 Sat 29

S33 2007-223T23:20 Sat 2007-265T20:51 Sat 42

S34 2007-265T20:51 Sat 2007-305T18:40 Thu 40

S35 2007-305T18:40 Thu 2007-347T16:15 Thu 42

S36 2007-347T16:15 Thu 2008-021T13:35 Mon 39

S37 2008-021T13:35 Mon 2008-047T11:51 Sat 26

S38 2008-047T11:51 Sat 2008-083T01:50 Sun 36

S39 2008-083T01:50 Sun 2008-110T07:18 Sat 27

S40 2008-110T07:18 Sat 2008-152T04:27 Sat 42

S41 2008-152T04:27 Sat 2008-187T00:00 Sat 35

*Note that S1 begins before the "official" start of tourat SOI on July 1, 2004. This was done to include thePhoebe flyby in the first tour sequence.

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2.2 INTERPLANETARY TRAJECTORY

Cassini's baseline trajectory is a VVEJGA (flybys of Venu s tw ice, Earth and Jup iter) trajectory.This multiple gravity-assist trajectory is necessary because no existing launch vehicle/ up perstage combination can p lace a spacecraft of Cassini's mass on a d irect trajectory to Satu rn. Theminimum C3 (or laun ch energy) requ ired for a d irect trajectory in 1997 is 108 km

2/ s2. A JGAtrajectory, with a single gravity-assist at Jup iter, would require a C3 of 83 km

2/ s2. Themaximum C3 achievable by the Titan IV (SRMU)/ Centaur for the launch m ass of Cassini was

34 km2

/ sec2

.This trajectory starts the spacecraft inward from the Earths orbit, toward Venus, where thefirst Venus gravity assist places the spacecraft on a nearly resonant Venus-to-Venus transfer. Aman euver at ap helion of this loop lowers perihelion, allowing the trajectory to intersect Venusearlier, and with a greater flight p ath an gle. The second flyby at Venus targets the spacecraftfor a very quick transfer (approximately eight w eeks) to Earth. This extremely fortuitousplanetary p hasing eliminates the need for an ad ditional trajectory loop in the inner solarsystem. The spacecraft grazes Mars orbit on the Venus 1 - Venus 2 leg, and passes throu gh th easteroid belt on the Earth - Jupiter leg of the trajectory. No asteroid flyby is included in thebaseline du e to a combination of ground system resource constraints and the high V cost totarget to even the closest asteroid encounter. The Jup iter flyby imp arts the remaining velocityrequ ired to reach Saturn, where ar rival occurs on 1 Ju ly 2004. Figures 2.3 and 2.4 show the

spacecraft interplanetary trajectory.

2.3 TOUR OVERVIEW

The reference tour consists of 75 orbits of Saturn with various orientations, orbital periodsranging from 7 to 118 days, and Saturn -centered periapsis radii ranging from abou t 2.7 to 15.6RS (Saturn radii). Orbital inclination with respect to Saturn's equator ranges from 0 75.6 ,provid ing opp ortun ities for ring imaging, magn etospheric coverage, and radio (Earth), solar,and stellar occulta tions of Satu rn, Titan, and the ring system. A total of 45 targeted Titan flybysoccur du ring the reference tour. Of these, 41 have flyby altitudes less than 2800 km and twohave flyby altitudes greater than 10,000 km. Titan flybys are used to control the sp acecraft'sorbit abou t Saturn as well as for Titan science acqu isition. The tou r also contains 7 close flybysof icy satellites, and 30 additional d istant flybys of icy satellites within 100,000 km.

Close Titan flybys are capable of making large chan ges in the orbiters trajectory. A single closeflyby of Titan can change the orbiters Saturn-relative velocity by m ore than 800 m/ s.How ever, Titan is the only satellite of Saturn w hich is massive enough to use for orbit controldu ring a tou r. The masses of the others are so small that even close flybys (within severalhu nd red km) only change the orbiters trajectory slightly. Consequently, the Cassini tourconsists mostly of Titan flybys. This places a restriction that each Titan flyby must p lace theorbiter on a t rajectory lead ing back to Titan. The orbiter cann ot be targeted to a flyby of asatellite other than Titan u nless the flyby lies almost along a return path to Titan. The largenu mber of Titan flybys does result in extensive coverage of Titan (Figure 2.7).

Figure 2.5 shows a view from above Saturn's north pole of all tour orbits in a rotatingcoord inate system in which the Sun direction is fixed. This type of figure is often referred to as

a "petal plot" du e to the resemblance of the orbits to petals of a flower. The broad range of orbitorientations allows d etailed su rvey of the magnetosphere and atmosp here of Saturn . Figure 2.6shows a "side view", from a d irection perp end icular to the plane formed by the Saturn-Sun lineand Saturns north pole, in w hich th e inclination of the orbits is apparen t. The tou r is describedin d etail in the following subsections.

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VENUS 2 FLYBY

24 JUN 1999

DEEP-SPA

MANEUV

DEC 19

EARTH FLYBY

18 AUG 1999

VENUS 1 FLYBY

26 APR 1998

LAUNCH

15 OCT 1997

Figure 2.3 Cassini Cruise Trajectory

TICKS EVERY 30 DAYS

TO

JUPITER

PER27 MAR 1998 0

29 JUN 1999 0

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Figure 2.4 CASSINI CRUISE TRAJECTORY

VENUS 1 SWINGBY

26 APR 1998

VENUS 2 SWINGBY

24 JUN 1999

EARTH SWINGBY18 AUG 1999

DEEP SPACE

MANEUVER

3 DEC 1998

LAUNCH

15 OCT 1997

JUPITER FLYBY

30 DEC 2000

27

29

SATURN ARR

1 JUL 200

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Figure 2.5 Tour Petal Plot-North Pole View

(+X parallel to Satu rn to Sun direction, +Z Saturn N. Pole)

Figure 2.6 Tour Petal Plot - Side View

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Figure 2.7 Titan Groun d Tracks

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Each orbit abou t Saturn is assigned a rev number from 1 to N incrementing at ap oapsis (whereone orbit end s, and the next begins). The p artial orbit from SOI to the first ap oapsis is orbit 0.Each satellite encounter is assigned a u nique satellite encoun ter label consisting of a threedigit rev number on w hich the encounter occurs followed by a two character body ind icator.For the major nine satellites (Mimas, Enceladus, Tethys, Dione, Rhea, Titan, Hyperion, Iapetus,and Phoebe), the first tw o letters are un ique and are used as the body ind icator. Encounters ofsatellites occur either inbound (before Saturn periapsis) or outbound (after Saturn periapsis).

Orbit orientation defines the location of apoapsis of the Saturn centered orbit w ith respect tothe Sun d irection which is an important consideration for observations of Saturnsmagn etosphere and atmosp here. Orbit orientation may be defined by an angle or a local truesolar time (LTST) as dep icted in Figure 2.8. The orbit orientation angle is measured clockwisein the Saturn equatorial plane from the p rojection of the SaturnSun line in the equatorialplane to the projection of the Saturn-apoapsis line. The local true solar tim e (LTST), measuredin hou rs (or hh:mm :ss), is obtained by scaling th e orbit orientation angle by (24 hours/ 360).

DAWNDUSK

SUN

MIDNIG HT / TAIL

S/ C Orbit

View From Saturn N orth Pole

Saturn

Orbit Orientation Angle = 90 ,

Local True Solar Time (LTST)

= 6 AM

LTST = 06:00

= 6 AM

LTST = 0:00= 12 AM

LTST =18:00

= 6 PM

Figure 2.8 Defin ition of Orb it Orientation

NOON

LTST = 12:00 = 12 PM

Projection of Saturn-Sun

Direction in Saturn

Equatorial Plane

Projection of Saturn -

Apoapsis Direction in

Saturn Equatorial Plane

The time available for observations of Saturns lit side decreases as the orbit rotates tow ard theanti-sun d irection. Arrival cond itions at Saturn fix the initial orientation at about 90 wh ich isequivalent to 6 AM LTST. Due to th e motion of Saturn around the Sun, the orbit orientationincreases with tim e, at a rate of orientation of about 1/ month, which over the four-year tourresults in a total rotation of about 48 (3.2 hou rs) in the clockwise direction (as seen from above

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Saturns north pole). Period-changing targeted flybys that rotate th e line of apsides m ay beused to add to or subtract from this dr ift in orbit orientation. The p etal plot of Figure 2.5 showshow targeted flybys combine w ith orbit d rift to rotate the orbit from the initial orientationclockwise most of the w ay aroun d Saturn to near the Sun line. In the coordinate system used inthis figure, the d irection to the Sun is fixed.

A targeted flyby is one where the orbiters trajectory has been d esigned to pass th rough aspecified aimpoint (latitud e, longitud e, and altitude) at closest approach. At Titan, theaimpoint is selected to p rodu ce a desired change in the trajectory using th e satellitesgravitational influence. Flybys within a few th ousand km of Titan m ust be targeted d ue to thelarge V imparted by Titan. At targeted flybys of icy satellites, the aimpoint is generallyselected to optimize the opportunities for scientific observations, since the gravitationalinfluence of those satellites is small. However, in some cases the satellites gravita tionalinfluence is great enou gh to cause unacceptably large V penalties for some aimpoints, whichmakes it necessary to constrain the r ange of allowable aimp oints to avoid th is penalty.

If the closest app roach aimp oint d uring a flyby is not controlled, the flyby is referred to as anon-targeted flyby. Flybys of Titan at d istances greater than 11,000 km (with the notableexcept ion of the Probe Titan flyby 003Tc) are non -targeted flybys. Flybys of satellites otherthan Titan at distances greater than a few th ousand kilometers are usu ally non-targeted flybys.If the closest app roach p oint is far from the satellite, or if the satellites mass is small, the

gravitational effect of the flyby can be sm all enough th at the aim point at the flyby need not betightly controlled in order to ensure a return path to Titan. How ever, the gravitationalinfluence of the flyby is not the sole criteria for d istingu ishing between targeted and non-targeted flybys. Operations constraints on satellite encounter frequency may force some closeicy satellite flybys(usu ally with in a few days of a Titan flyby) to be non-targeted .Opp ortun ities to achieve non-targeted flybys of smaller satellites occur frequently d ur ing thetour. These are importan t for global imaging.

If the transfer angle between two Titan flybys is an integer multiple of 360 (i.e., the two flybysencoun ter Titan at the same p lace in its orbit), the orb it connecting the tw o flybys is called aresonant orbit (Figure 2.9).The period of a Titan-resonant orbit is an integer mu ltiple ofTitan's 16 d orbital period. The plane of the transfer orbit between an y tw o flybys is formed bythe p osition vectors of the flybys with respect to Saturn . In this case, an infinite num ber oforbital planes connect the flybys; therefore, for resonant orbits, the plane of the transfer orbitcan be inclined significantly to Saturns equator. The Titan flyby altitude for resonant transfersis often the m inimum perm itted value of 950 km since maximum inclination change per flybyis usually desired.

If two successive flybys encounter Titan at a d ifferent p lace in its orbit, the orbit connecting thetwo flybys called a non-resonant orbit (Figure 2.10). Non-resonant orbits have orbital periodswh ich are n ot integer mu ltiples of Titan's period. Non -resonant transfer orbits connectinbound Titan flybys to outbound Titan flybys, or visa versa. Except for the special case of a180 tran sfer, the Titan position vectors at successive encounters are not p arallel (i.e., Titan isencountered at d ifferent locations in its orbit), and therefore the orbital plane formed by theposition vectors of the tw o flybys is un ique and lies close to Titans orbital plane (wh ich lies

close to Saturn s equatorial plane). Non resonant tran sfers therefore have near zero orbitinclination. The Titan flyby altitude for nonresonant transfers is usually mu ch greater than theminimu m flyby altitude value of 950 km since inclination is constrained to be near zero andthus the Titan gravity assist must be used solely to obtain a retu rn trajectory to Titan.

A 180 transfer (Figure 2.10) is a very sp ecial case of a Titan non resonant tr ansfer. In a 180transfer, the transfer angle between tw o Titan flybys is an odd mu ltiple of 180. In this case,successive Titan encounters occur first at the ascending node of Titans orbit and then thedescending nod e, or visa versa. Only one 180 tran sfer occurs in the tour. Significant

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inclination and orbit orientation change a re accomp lished du ring a sequence of flybys wh ichincludes a 180 transfer.

RESON ANT TRAN SFER

DEFINITION : Next Titan encounter occurs at SAME place in Titan's orb it as current encounter , i.e.

s/ c orbit is in resonance with Titan orbit. Used pr imarily for changing s/ c orbit inclination or when

already in an inclined orbit, changing s/ c orbit period.

Titan at curren t encounter

Titan at n ext encounter

Saturn

S/ C OrbitTitan Orbit

n complete Titan revs per m complete s/ c revs

where n , m = 1, 2, 3, ...

Line of Nod es

Figu re 2.9 Definition of Resonan t Transfer

NONRESONANT TRANSFER

DEFINITION: Next Titan encounter occurs at a DIFFERENT place in Titan's orbit as current encounter,i.e. s/c orbit is NOT in resonance with Titan orbit. Used primarily for changing s/c orbit orientation(local solar time of s/c orbit apoapsis).

Titan at current encounter

Titan at next encounter

.8 revs later

Saturn

S/C OrbitTitan Orbit

Transfers are from Titan outbound from Saturn to Titan inbound to Saturn or visa versa. S/C orbit planemust contain Titan at current encounter, Titan at next encounter, and Saturn. Therefore, s/c orbitinclination must be near zero unless Titan encountered at opposite sides of its orbit (i.e., 180 deg. transfer).

Outbound

Inbound

Titan at currentencounter

Titan at nextencounter 1.1 revs

later

Saturn

S/C Orbit

Titan Orbit

Outbound

InboundLine of S/CNodes =

Saturn toTitanDirection

Sample Low Inclination Transfer Sample Inclined 180 deg. Transfer

Figure 2.10 Definition of Non resonant and 180 Transfer

Table 2.3 shows a breakdow n of the tour into segments and shows th e main characteristics ofeach segment. Segments a re d elineated by Titan encounters since only at Titan encounters isthe orbital geometry significantly altered. An expand ed description of each segm ent follows.Recall that the first 3 digits of the encounter label are the rev nu mber and that encoun ter labelsin parentheses use the old encounter n um bering scheme. Tables of satellite encountercond itions as well as an integrated rev by rev sum mary of key tour geometries can be found inSection 2.4.

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Tab le 2.3 Tour Segmen t CharacteristicsEncounte

rsDates Figure Comments

SOI-Tc(SOI-Tc)

Jul 2004 Jan 2005

2.11,2.12

SOI, PRM, target for Probe mission at Tc, reduce period & inclination

Tc-14TI(Tc-T7)

Jan 2005 Sep 2005

2.13,2.14

Reduce inclination to enable nonresonant transfer to establish optimal occultationgeometry, raise inclination for Saturn/ring occultations and lower again to equator.Two targeted Enceladus flybys.

14TI-26TI

(T7-T16)

Sep 2005

Jul 2006

2.15 Rotate clockwise toward anti-sun direction to establish optimal magnetotail

geometry. Targeted Hyperion, Dione, and Rhea flybys.26TI-47TI(T16-T33)

Jul 2006 Jun 2007

2.16,2.17

Deep magnetotail passage initiating 180-deg. transfer sequence (includingseveral revs for ring observations)

47TI-49TI(T33-T35)

Jun 2007 Oct 2007

2.18 Rotate clockwise to optimize atmospheric observation and Saturn/ring occultationgeometries

49TI-End(T35-T44)

Oct 2007 Jul 2008

2.19,2.20

Increase inclination to 75.6 (maximum value in tour). Targeted Iapetus andEnceladus flyby. Last Titan flyby is 69TI (T44).

SOI-Tc (Figures 2.11 and 2.12)

This tour segment has been significantly redesigned since the last Mission Plan release dueProbe mission considerations. The remaining tou r segments only contain a few tw eaks to thelatest T18-5 reference tour and will be described in subsequent segments. The spacecraftapp roaches Saturn from below the r ing plane on a trajectory inclined about 17 with respect to

Saturn s equator [ Satu rns equatorial plane is inclined 26.7 with resp ect to its orbit arou ndthe Sun . Satu rns orbit is itself inclined 2.49 with respect to the ecliptic.]. The first Titan flybyis inbound du e to Probe delivery considerations.

In February 2000, it was d iscovered th at the bit synchronizer of the H uygens r eceiver on theorbiter has a band width th at is too small to accommod ate the Dopp ler shift of the relay signal.In order to recover the Probe mission, the redesign reduces the Dopp ler shift between th eProbe and orbiter. To reduce the relay Dopp ler shift, the closest approach altitude of theorbiter at the Probe relay encounter (Tc) was raised to 60000 km w hich redu ces the radialcomponen t of the orbiters velocity relative to th e Probe and hence the Doppler shift of therelay signal

Three new Titan encounters: Ta, Tb, and Tc have been designed w ith a d istant flyby du ring

Probe delivery on Tc. These three initial Titan encounters replace the first two Titanencoun ters of the T18-5 tou r. The new tour therefore conta ins an add itional Titan flyby albeitat very high altitud e. Following Tc, the tr ajectory rejoins the T18-5 tour a t the 3TI (T3)encoun ter. After the 3TI encoun ter, the encoun ter times d iffer from those in T18-5 by less than4 hours and the geometry of the encounters and occultations remain essentially the same.

The orbiters inclination is gradu ally reduced to enable a nonresonan t transfer in the n ext toursegment needed to establish optimum Saturn / ring occultation geometry. Therefore, the initialseries of Titan flybys must a ll take place at the sam e place in Titans orbit (i.e. they all mu st beresonant, inbound flybys). The initial flybys quickly reduce period, as well as inclination, tomaximize the nu mber of Titan flybys in the tour. These three inboun d, period -reducing flybysrotate the line of apsides coun terclockwise (Figure 2.11). This moves the apoap se toward the

Sun line w hich provides time for observations of Saturns atmosphere and helps establish thegeometry needed for near equatorial Saturn/ ring occultations later in the tour.

If the Probe cannot be d elivered at the Tc flyby, a contingency trajectory exists tha t allows asecond chance to deliver the Probe. This contingency retargets Tc to a lower altitud e andintrodu ces a n ew distant flyby, Td, for Probe d elivery. How ever, this contingency causesCassini to fall off of the tou r and it d oesn't retu rn to the T18-5 tour until the 13TI (T6) flyby. Inthis case, the first two targeted Enceladus flybys w ill be lost as well as 3 of the 7 d iametricSaturn/ ring occultations. Due to the severe science imp act of this contingency, every effortwill be made to deliver the Probe on the nom inal Tc encounter.

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Tc-14TI (Tc-T7) (Figures 2.13 and 2.14)

The 3TI (T3) flyby initiates a nonresonant inbou nd to outbou nd transfer that orients the line ofnodes nearly normal to the Saturn -Earth line. This orientation minimizes the inclinationrequired to achieve an occultation of Saturn and results in Saturn / ring occultations wh ich arecharacterized by ingress and egress close to Saturns equatorial plane (i.e., near-equatorial).The use of outbou nd flybys for the early tour d awn orbit orientation minimizes the Saturn-spacecraft distance du ring these occultations w hich improves science return since thefootprint" projected on the rings is minimized, improving the spatial resolution of the"scattered" radio signal observations. This is an importan t influence on the d esign of the tour .

A targeted Encelad us (4EN, (E1)) flyby is obtained d ur ing the 3TI-5TI (T3-T4) nonresonan ttranfer. Note that targeted flybys of the icy satellites such as 4EN are usually obtained onorbits wh ich are also used to establish d esired Saturn-relative geometries.

The resonant ou tbou nd flybys 5TI (T4) and 6TI (T5) increase inclination to ~22 to set up theSaturn/ ring equatorial occultations.During the 6TI (T5) to 13TI (T6) segmen t, seven near -equatorial occultations of Earth and Sun by Saturn an d its rings (one on each 18.2 d periodorbit) occur. During these seven orbits, the orbiter crosses Saturns equa tor near Enceladu sorbit; on the fourth orbit, Enceladus an d the spacecraft both a rrive at nearly the same p oint inEnceladus orbit at the same time, and th e second targeted flyby of Enceladu s (11EN, (E2))occurs. Enceladus gravity is too weak to displace inclination significantly from the valuerequired to achieve occultations.

The 13TI (T6) flyby decreases inclination once again to near Saturn 's equator to enable anonresonan t transfer in ord er to begin the n ext tour segmen t. Unlike the last officially releasedtour, the 13TI (T6) flyby altitud e was raised from 950 to ~4000 km in ord er to avoid a G ringcrossing but the 14TI (T7) altitud e was low ered from ~4000 to 950 km. These two Titan flybystherefore do not change the d istribution of Titan flyby altitudes.

14TI-26TI (T7-T16) (Figure 2.15)

The 14TI-17TI (T7-T8) nonresonant transfer initiates a series of alternating ou tbound / per iod-redu cing and inbound/ period-increasing flybys lasting abou t 10 mon ths. These flybys areused to rotate the orbit apoap sis clockwise toward the magnetotail to establish the geometry

required for a deep magn etotail passage. The period typ ically alternates between 23 d(outbound ) and 39 d (inbound ) with .8 to 1.1 revs between flybys since this sequence results inthe most rap id change in orbit orientation. The only exceptions to this pattern w ere orbitsused to obtain targeted icy satellites du ring these nonresonant transfers.

Following the 14TI (T7) flyby, a 19 d per iod, 2.8 rev nonresonant tr ansfer is used in ord er toachieve the first ta rgeted flybys of Hyp erion (15HY, (H1)) and Dione (16DI, (D1)) along theway . Comp ared to the last officially released tour , the Dione flyby aimp oint has been loweredin altitud e (to 500 km) and changed in B-plane angle per PSG request . Similarly, following the17TI (T8) flyby, a 28 d , 2.1 rev nonreson ant t ransfer is utilized to obtain the first targeted Rhea(18RH, R1) flyby.

26TI-47TI (T16-T33) (Figures 2.16, 2.17)

The 26TI (T16) flyby places apoapsis near th e ant i-Sun line at an inclinat ion of ~15 to achievepassage throu gh the cur rent sheet in the m agnetotail region. Apoapsis distance is about 49 RS,exceeding the 40 RS MAPS requirement associated with magn etotail passage. At distances thisfar from Saturn , the current sheet is assum ed to be swep t away from Saturn s equatorial planeby the solar wind . This flyby also initiates the 180 transfer sequence.

A series of 17 Titan flybys comprise the 180 tran sfer sequence. A series of 9 resonanttransfers, usually with period of 16 d, increases inclination and decreases orbit eccentricity to apoint at w hich both the ascend ing and descending nodes of the spacecraft orbit are at Titans

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orbital rad ius. At an inclination of ~59, a nonresonant 180 transfer is then p erformed (theorbit show n in bold in Figures 2.16 and 2.17), i.e., the true an omaly of Titan in its orbit at w hichit is encountered by the sp acecraft on su ccessive flybys d iffers by 180 (actually 540). A seriesof 8 16 day per iod orb its then d ecreases inclination back to near zero and increases eccentricityback to its original value. Orbit orienta tion is changed by ~135 to ~8 PM LTST over th e 11month sequence du ration.

Most Titan flyby altitud es are at the minimum perm itted value of 950 km in order to m aximize

the inclination and eccentr icity change at each flyby. Such low altitu de Titan flybys arepreferred for m any science observations. The 31TI (T20) flyby redu ces period to 12 daysresulting in 4 revs over an interval of 48 d between Titan flybys in order to p rovide ad ditionalORS observat ions of the rings at a tim e of favorable observa tional geometry. This 48-dayinterval also serves to reduce operational stress on the groun d system.

47TI-49TI (T33-T35) (Figure 2.18)

The 47TI (T33) and 48TI (T34) nonresonant t ransfers rotate the orb it petal furth er clockwise(toward noon) to enable Saturn atm ospheric observations at both great d istance (> 40 Rs) andlow phase angle. This tour segment p rovides mu ch of the long integration time daytimeatmosp heric observation opportun ities. The nonresonant tran sfers also move the line of nodescloser to the Sun line in order to establish the geometry needed for near p olar Saturn / ringoccultations in th e next tour segm ent.

49TI-End Baseline Mission (post 69TI) on Rev 74 (T35-post T44) (Figures 2.19 and 2.20)

This segment is comp rised solely of resonant transfers wh ich gr adu ally raise inclination to themaximu m value attained in the tour. The first targeted Iapetu s encounter (49IA (I1)) isobtained on the 49TI-50TI (T35-T36) resonant tran sfer at an inclinat ion of ~6. Note that theascend ing nod e on which this targeted Iapetus encoun ter is obtained differs ~180 from theascend ing node desired for the maximum inclination sequence. The desired ascend ing nodefor the maximum inclination segment places periapsis below the ring plane such that th espacecraft can view th e illum inated side of the rings at Saturn p eriapsis (note Solar d eclinationis negative during this time period). The third targeted Enceladus (61EN, (E3)) encounter isobtained on th e 59TI-62TI (T41-T42) tran sfer. Note that th is Enceladus flyby is occulted from

the Sun at closest approach.Following th e targeted 49IA (I1) Iapetu s flyby, starting at 50TI (T36), a series of 10 outbou ndTitan r esonant tran sfers are u sed increase inclination as mu ch as possible for ring observationsand in-situ fields and p articles measurements. These resonant transfers continue until the endof the baseline tou r on July 1, 2008 (rev 74) four years after insertion in to orbit about Satu rn .The LTST of these orbits is near noon to enable near polar Saturn / ring occultations at closedistances.

The maximum inclination possible is dictated primarily by the Titan-relative V-infinity (fixed),orbital period (free), and the num ber of Titan flybys (constrained by time left in tour ) devotedto increasing inclination. The closest approach altitudes d uring this segment are kept at theminimu m allowed value of 950 km to maximize inclination change at each flyby. The orbitalperiod m ust be grad ually redu ced in ord er to furth er increase inclination wh ich d ecreases thedescending nod e crossing distance to the point w here ring hazard avoidance becomes alimiting constraint. The orbital characteristics after the last Titan flyby in the tour, 69TI (T44),are a per iod of 7.1 d, inclination of 75.6, and descending node distance of 2.7 Rs. Fiveperiapses are completed at this maximum inclination before the end of the baseline tour .

The aimpoint at the last Titan flyby is chosen to target the orbiter to a Titan flyby on 7/ 31/ 08(64 days an d 9 revs after the 69TI (T44) flyby), providing th e opp ortun ity to p roceed with moreflybys du ring an extended m ission, if resources allow. Nothing in th e design of the tourprecludes an extend ed mission.

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Figure 2.12 Tour Segm ent SOI-Tc Sid e View

Figure 2.13 Tou r Segm en t Tc-14TI (Tc-T7)

(+X parallel to Saturn to Sun direction, +Z Saturn N. Pole)

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Figure 2.14 Tou r Segm en t Tc-14TI (Tc-T7) Side View

Figure 2.15 Tour Segment 14TI-26TI (T7-T16) [~Zero Inclination]

(+X parallel to Saturn to Sun direction, +Z Saturn N . Pole)

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1 80 Transf er

Orbit

i=59

Orbit

Orientation

Change Titan location first9 inbound flybys

Titan location last

8 outbound flybys

Titan Orbit

i=25 ,

period=16 d

i=2 ,

period=16 d

i=15 ,

period= 24 d

SUN

Midnight

Dusk

Figure 2.16 Tour Segm en t 26TI-47TI (T16-T33)

(+X parallel to Satu rn to Su n direction, +Z Saturn N. Pole)

180 Transfer Ori=59

Figure 2.17 Tour Segm en t 26TI-47TI (T16-T33) Side View

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Figure 2.18 Tour Segment 47TI-49TI (T33-T35) [~Zero Inclination]


Figure 2.19 Tour Segmen t 49TI-End Baseline Mission (post 69TI) on Rev 74 (T35-pos t T44)


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2-23

Figure 2.20 Tour Segment 49TI-End Baselin e Mission (post 69TI)

on Rev 74 (T35-post T44) Sid e View

2.4 REFERENCE TABLES

The following tables provide reference data for the Cassini mission. Encoun ters du ring thenominal tour and a ll events dur ing the tour are given. Finally, a utility table translates betweencalendar date, weekday and day of year for planning purposes.

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CASSINI TOUR ENCOUNTER SUMMARY

RevName Old Event Epoch (SCET) DOY DOW Altitude Inbound/ Speed Phase To Next

Name km outbound km/s deg Targ

0 0PH (t) P1 Phoebe 2004-Jun-11 19:33 163 Fri 1,997 inbound 6.4 25

0 0MI (nt) Mimas 2004-Jul-01 00:30 183 Thu 76,424 inbound 22.3 80

0 0TI (nt) Titan 2004-Jul-02 09:30 184 Fri 338,958 outbound 8.3 67

a aTI (t) N/A Titan 2004-Oct-26 15:30 300 Tue 1,200 inbound 6.1 91 48b bTI (t) N/A Titan 2004-Dec-13 11:37 348 Mon 2,358 inbound 6.0 98 32

b bDI (nt) Dione 2004-Dec-15 02:11 350 Wed 81,592 inbound 5.3 93

c cIA (nt) Iapetus 2005-Jan-01 01:28 001 Sat 64,907 inbound 2.1 106

c cTI (t) N/A Titan 2005-Jan-14 11:04 014 Fri 60,000 inbound 5.4 93 32

3 3TI (t) T3 Titan 2005-Feb-15 06:54 046 Tue 950 inbound 6.0 102 22

3 3EN (nt) Enceladus 2005-Feb-17 03:24 048 Thu 1,179 outbound 6.6 98

4 4EN (t) E1 Enceladus 2005-Mar-09 09:06 068 Wed 499 inbound 6.6 43 22

4 4TE (nt) Tethys 2005-Mar-09 11:42 068 Wed 82,975 outbound 6.9 64

5 5EN (nt) Enceladus 2005-Mar-29 20:20 088 Tue 63,785 inbound 10.1 134

5 5TI (t) T4 Titan 2005-Mar-31 19:55 090 Thu 2,523 outbound 5.9 65 16

6 6MI (nt) Mimas 2005-Apr-15 01:20 105 Fri 77,233 outbound 13.6 94

6 6TI (t) T5 Titan 2005-Apr-16 19:05 106 Sat 950 outbound 6.1 127 89

7 7TE (nt) Tethys 2005-May-02 21:04 122 Mon 64,990 inbound 10.0 118

7 7TI (nt) Titan 2005-May-04 05:10 124 Wed 860,004 outbound 10.2 1538 8EN (nt) Enceladus 2005-May-21 07:19 141 Sat 92,997 outbound 8.1 81

9 9TI (nt) Titan 2005-Jun-06 18:50 157 Mon 425,973 inbound 5.8 82

10 10TI (nt) Titan 2005-Jun-22 12:27 173 Wed 920,423 inbound 3.7 65

11 11EN (t) E2 Enceladus 2005-Jul-14 19:57 195 Thu 1,000 inbound 8.1 43 39

12 12MI (nt) Mimas 2005-Aug-02 03:52 214 Tue 45,112 inbound 6.5 83

12 12TI (nt) Titan 2005-Aug-06 12:33 218 Sat 841,452 outbound 3.8 62

13 13TI (t) T6 Titan 2005-Aug-22 08:39 234 Mon 4,015 outbound 5.8 42 16

14 14TI (t) T7 Titan 2005-Sep-07 07:50 250 Wed 950 outbound 6.1 84 19

15 15TE (nt) Tethys 2005-Sep-24 01:29 267 Sat 33,295 outbound 7.7 76

15 15TI (nt) Titan 2005-Sep-24 22:01 267 Sat 910,272 outbound 10.7 148

15 15HY (t) H1 Hyperion 2005-Sep-26 01:41 269 Mon 990 outbound 5.6 45 16

16 16TI (nt) Titan 2005-Oct-10 22:20 283 Mon 777,198 inbound 9.7 65

16 16DI (t) D1 Dione 2005-Oct-11 17:58 284 Tue 500 inbound 9.0 66 16

16 16EN (nt) Enceladus 2005-Oct-12 03:29 285 Wed 42,635 outbound 6.6 75

17 17TI (t) T8 Titan 2005-Oct-28 03:58 301 Fri 1,446 inbound 5.9 105 30

18 18RH (t) R1 Rhea 2005-Nov-26 22:35 330 Sat 500 inbound 7.3 87 30

19 19EN (nt) Enceladus 2005-Dec-24 20:23 358 Sat 97,169 inbound 6.9 133

19 19TI (t) T9 Titan 2005-Dec-26 18:54 360 Mon 10,429 outbound 5.6 67 20

20 20TI (t) T10 Titan 2006-Jan-15 11:36 015 Sun 2,042 inbound 5.8 121 43

21 21TI (t) T11 Titan 2006-Feb-27 08:20 058 Mon 1,812 outbound 5.9 93 20

22 22TI (t) T12 Titan 2006-Mar-18 23:58 077 Sat 1,947 inbound 5.8 148 43

22 22RH (nt) Rhea 2006-Mar-21 07:01 080 Tue 85,935 outbound 5.3 136

23 23TI (t) T13 Titan 2006-Apr-30 20:53 120 Sun 1,853 outbound 5.8 121 20

24 24TI (t) T14 Titan 2006-May-20 12:13 140 Sat 1,879 inbound 5.8 163 43

25 25TI (t) T15 Titan 2006-Jul-02 09:12 183 Sun 1,911 outbound 5.8 148 20

26 26TI (t) T16 Titan 2006-Jul-22 00:25 203 Sat 950 inbound 6.0 105 48

27 27TI (nt) Titan 2006-Aug-18 17:48 230 Fri 339,190 outbound 4.8 121

28 28TI (t) T17 Titan 2006-Sep-07 20:12 250 Thu 950 inbound 6.0 45 16

28 28EN (nt) Enceladus 2006-Sep-09 20:00 252 Sat 39,842 outbound 10.3 11629 29TI (t) T18 Titan 2006-Sep-23 18:52 266 Sat 950 inbound 6.0 90 16

30 30TI (t) T19 Titan 2006-Oct-09 17:23 282 Mon 950 inbound 6.0 81 16

31 31TI (t) T20 Titan 2006-Oct-25 15:51 298 Wed 950 inbound 6.0 25 48

32 32EN (nt) Enceladus 2006-Nov-09 01:48 313 Thu 94,410 outbound 14.1 27

33 33DI (nt) Dione 2006-Nov-21 02:32 325 Tue 72,293 outbound 12.3 144

33 33TI (nt) Titan 2006-Nov-25 13:57 329 Sat 930,525 outbound 4.5 114

35 35TI (t) T21 Titan 2006-Dec-12 11:35 346 Tue 950 inbound 6.0 124 16

36 36TI (t) T22 Titan 2006-Dec-28 10:00 362 Thu 1,500 inbound 5.9 62 16

37 37TI (t) T23 Titan 2007-Jan-13 08:34 013 Sat 950 inbound 6.0 53 16

38 38TI (t) T24 Titan 2007-Jan-29 07:12 029 Mon 2,776 inbound 5.8 73 24

This list only includes flybys of Titan < 1,000,000 km and icy satellites < 100,000 km

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CASSINI TOUR ENCOUNTER SUMMARY

Rev Name Old Event Epoch (SCET) DOY DOW Altitude Inbound/ Speed Phase To Next

Name km outbound km/s deg Targ

39 39TI (t) T25 Titan 2007-Feb-22 03:10 053 Thu 953 outbound 6.3 161 16

40 40TI (t) T26 Titan 2007-Mar-10 01:47 069 Sat 956 outbound 6.3 149 16

41 41TI (t) T27 Titan 2007-Mar-26 00:21 085 Mon 953 outbound 6.3 144 16

42 42TI (t) T28 Titan 2007-Apr-10 22:57 100 Tue 951 outbound 6.3 137 16

43 43TI (t) T29 Titan 2007-Apr-26 21:32 116 Thu 951 outbound 6.3 130 16

44 44TI (t) T30 Titan 2007-May-12 20:08 132 Sat 950 outbound 6.3 121 16

45 45TE (nt) Tethys 2007-May-26 20:57 146 Sat 97,131 inbound 11.7 75

45 45TI (t) T31 Titan 2007-May-28 18:51 148 Mon 2,425 outbound 6.1 114 16

46 46TI (t) T32 Titan 2007-Jun-13 17:46 164 Wed 950 outbound 6.3 107 1647 47TE (nt) Tethys 2007-Jun-27 19:53 178 Wed 16,166 inbound 10.1 90

47 47MI (nt) Mimas 2007-Jun-27 22:56 178 Wed 89,730 inbound 16.2 110

47 47EN (nt) Enceladus 2007-Jun-28 01:15 179 Thu 90,769 outbound 9.4 55

47 47TI (t) T33 Titan 2007-Jun-29 17:05 180 Fri 1,942 outbound 6.2 96 19

48 48TI (t) T34 Titan 2007-Jul-19 00:39 200 Thu 1,302 inbound 6.2 34 43

49 49TE (nt) Tethys 2007-Aug-29 11:21 241 Wed 48,324 inbound 4.7 104

49 49RH (nt) Rhea 2007-Aug-30 01:26 242 Thu 5,098 outbound 6.7 46

49 49TI (t) T35 Titan 2007-Aug-31 06:34 243 Fri 3,227 outbound 6.1 87 10

49 49IA (t) I1 Iapetus 2007-Sep-10 12:33 253 Mon 1,000 outbound 2.4 65 22

50 50DI (nt) Dione 2007-Sep-30 06:27 273 Sun 56,523 inbound 5.6 47

50 50EN (nt) Enceladus 2007-Sep-30 10:53 273 Sun 88,174 inbound 6.1 99

50 50TI (t) T36 Titan 2007-Oct-02 04:48 275 Tue 950 outbound 6.3 67 48

51 51TI (nt) Titan 2007-Oct-22 00:47 295 Mon 455,697 inbound 4.1 29

52 52RH (nt) Rhea 2007-Nov-16 19:52 320 Fri 78,360 inbound 9.1 148

52 52TI (t) T37 Titan 2007-Nov-19 00:52 323 Mon 950 outbound 6.3 51 16

53 53MI (nt) Mimas 2007-Dec-03 05:28 337 Mon 79,272 inbound 14.8 138

53 53TI (t) T38 Titan 2007-Dec-05 00:06 339 Wed 1,300 outbound 6.3 70 16

54 54TI (t) T39 Titan 2007-Dec-20 22:56 354 Thu 953 outbound 6.3 61 16

55 55TI (t) T40 Titan 2008-Jan-05 21:26 005 Sat 949 outbound 6.3 37 48

57 57TI (nt) Titan 2008-Jan-22 21:06 022 Tue 860,776 inbound 4.5 70

59 59TI (t) T41 Titan 2008-Feb-22 17:39 053 Fri 959 outbound 6.4 30 19

61 61TI (nt) Titan 2008-Mar-10 19:15 070 Mon 922,539 inbound 6.3 123

61 61EN (t) E3 Enceladus 2008-Mar-12 19:05 072 Wed 995 inbound 14.6 56 13

62 62TI (t) T42 Titan 2008-Mar-25 14:35 085 Tue 950 outbound 6.4 21 48

64 64MI (nt) Mimas 2008-Apr-11 09:38 102 Fri 95,428 inbound 16.9 137

66 66TI (nt) Titan 2008-Apr-26 18:22 117 Sat 780,589 inbound 5.5 94

67 67TI (t) T43 Titan 2008-May-12 10:09 133 Mon 950 outbound 6.4 35 16

69 69TI (t) T44 Titan 2008-May-28 08:33 149 Wed 1,316 outbound 6.3 23

72 72TI (nt) Titan 2008-Jun-13 04:17 165 Fri 372,240 inbound 5.9 8974 74EN (nt) Enceladus 2008-Jun-30 08:07 182 Mon 99,092 inbound 21.6 66

This list only includes flybys of Titan < 1,000,000 km and icy satellites < 100,000 km

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CASSINI TOUR EVENT SUMMARY All times are in SCET. For events with nonzero duration, epoch given is start.

Seq Rev Name Event Epoch (SCET) Date DOW Comment

S1 0 S1 Begins 2004-136T00:00 May15 Sat Duration = 35 days

S1 0 TCM-20 2004-148T23:45 May27 Thu Phoebe targeting

S1 0 0PH (t) Phoebe 2004-163T19:33 Jun11 Fri Was P1; inbound 1,997 km, v= 6.4 km/s, Phase=25 deg

S1 0 TCM-21 2004-168T22:40 Jun16 Wed SOI targeting

S2 0 S2 Begins 2004-171T01:38 Jun19 Sat Duration = 42 days

S2 0 TCM-22 2004-173T22:15 Jun21 Mon Backup SOI targeting (contingency)

S2 0 0MI (nt) Mimas 2004-183T00:30 Jul01 Thu inbound 76,424 km, v= 22.3 km/s, Phase=80 deg

S2 0 Ring CRX Ascending 2004-183T00:47 Jul01 Thu r=2.6 Rs

S2 0 SOI Start 2004-183T01:12 Jul01 Thu SOI burn start, V= 632 m/s, ~102 min. durationS2 0 Earth OCC Ring 2004-183T01:35 Jul01 Thu Duration = 166 min.

S2 0 Sun OCC Ring 2004-183T01:36 Jul01 Thu Duration = 166 min.

S2 0 Periapse 2004-183T02:38 Jul01 Thu r=1.3 Rs, Phase=94 deg

S2 0 SOI End 2004-183T02:54 Jul01 Thu SOI burn end

S2 0 Earth OCC Saturn 2004-183T03:33 Jul01 Thu Duration = 36 min.

S2 0 Sun OCC Saturn 2004-183T03:36 Jul01 Thu Duration = 32 min.

S2 0 Ring CRX Descending 2004-183T04:34 Jul01 Thu r=2.6 Rs

S2 0 0TI (nt) Titan 2004-184T09:30 Jul02 Fri Was T0; outbound 338,958 km, v= 8.3 km/s, Phase=67 deg

S2 0 OTM-001 SOI c/u 2004-185T21:40 Jul03 Sat SOI cleanup

S2 0 SEP=3 deg Conjunction 2004-187T04:20 Jul05 Mon SEP Decreasing, successful commanding not req.

S2 0 SEP=2 deg Conjunction 2004-188T10:12 Jul06 Tue SEP Decreasing, plan for RTE-1896, no SSR playback

S2 0 SEP=1 deg Conjunction 2004-189T16:27 Jul07 Wed SEP Decreasing, schedule no DSN passes

S2 0 SEP=1 deg Conjunction 2004-192T01:04 Jul10 Sat SEP Increasing, plan for RTE-1896, no SSR playback

S2 0 SEP=2 deg Conjunction 2004-193T07:11 Jul11 Sun SEP Increasing, successful commanding not req.

S2 0 SEP=3 deg Conjunction 2004-194T12:51 Jul12 Mon SEP Increasing

S2 0 OTM-001A SOI c/u 2004-199T21:00 Jul17 Sat SOI cleanup

S3 0 S3 Begins 2004-212T23:05 Jul30 Fri Duration = 43 days

S3 0 OTM-002 PRM 2004-236T17:00 Aug23 Mon Periapsis raise V= 392 m/s

S3 a Apoapse 2004-240T12:38 Aug27 Fri P=123.8 d, i=17.6, r=150.5 Rs, Phase=87 deg, LTST=5:47

S3 a OTM-003 PRM c/u 2004-251T18:00 Sep07 Tue Periapsis raise clean up

S4 a S4 Begins 2004-255T19:10 Sep11 Sat Duration = 35 days

S5 a S5 Begins 2004-290T18:40 Oct16 Sat Duration = 28 days

S5 a OTM-004 ATI-3 2004-297T07:30 Oct23 Sat

S5 a aTI (t) Titan 2004-300T15:30 Oct26 Tue Was T N/A; inbound 1,200 km, v= 6.1 km/s, Phase=91 deg

S5 a Ring CRX Ascending 2004-300T16:53 Oct26 Tue r=19.5 Rs

S5 a Periapse 2004-302T10:19 Oct28 Thu r=6.2 Rs, Phase=104 deg

S5 a Ring CRX Descending 2004-302T19:58 Oct28 Thu r=8.1 Rs

S5 a OTM-005 ATI+3 2004-303T13:30 Oct29 Fri

S6 a S6 Begins 2004-318T16:59 Nov13 Sat Duration = 33 days

S6 b Apoapse 2004-326T08:41 Nov21 Sun P=47.9 d, i=13.8, r=78.1 Rs, Phase=77 deg, LTST=5:09

S6 b OTM-006 APO 2004-326T05:00 Nov21 Sun

S6 b OTM-007 BTI-3 2004-345T04:00 Dec10 Fri

S6 b bTI (t) Titan 2004-348T11:37 Dec13 Mon Was T N/A; inbound 2,358 km, v= 6.0 km/s, Phase=98 degS6 b Ring CRX Ascending 2004-348T13:29 Dec13 Mon r=19.3 Rs

S6 b bDI (nt) Dione 2004-350T02:11 Dec15 Wed inbound 81,592 km, v= 5.3 km/s, Phase=93 deg

S6 b Periapse 2004-350T05:58 Dec15 Wed r=4.8 Rs, Phase=109 deg

S6 b Ring CRX Descending 2004-350T11:14 Dec15 Wed r=5.8 Rs

S7 b S7 Begins 2004-351T15:03 Dec16 Thu Duration = 37 days

S7 b OTM-008 PTM 2004-353T03:45 Dec18 Sat Probe targeting

S7 b OTM-009 PTM c/u 2004-357T03:30 Dec22 Wed Probe targeting cleanup

S7 b Probe Release 2004-359T09:00 Dec24 Fri At entry interface - 21 d

S7 b OTM-010 ODM 2004-364T03:00 Dec29 Wed Orbit deflection V= 26 m/s

S7 c Apoapse 2004-366T07:17 Dec31 Fri P=31.9 d, i=8.6, r=59.5 Rs, Phase=71 deg, LTST=4:45

S7 c cIA (nt) Iapetus 2005-001T01:28 Jan01 Sat inbound 64,907 km, v= 2.1 km/s, Phase=106 deg

S7 c Probe Entry 2005-014T09:00 Jan14 Fri Entry interface alt=1270 km, Tc-2.1 h

S7 c cTI (t) Titan 2005-014T11:04 Jan14 Fri Was T N/A; inbound 60,000 km, v= 5.4 km/s, Phase=93 deg

S7 c Ring CRX Ascending 2005-014T14:55 Jan14 Fri r=19.1 Rs

S7 c Periapse 2005-016T06:27 Jan16 Sun r=4.9 Rs, Phase=107 deg

S7 c OTM-011 CTI+2 2005-016T09:30 Jan16 Sun

S7 c Ring CRX Descending 2005-016T11:57 Jan16 Sun r=5.9 RsS8 c S8 Begins 2005-022T10:38 Jan22 Sat Duration = 36 days

S8 c OTM-012 ~APO 2005-028T15:13 Jan28 Fri

S8 3 Apoapse 2005-032T03:25 Feb01 Tue P=31.8 d, i=8.5, r=59.2 Rs, Phase=73 deg, LTST=4:53

S8 3 OTM-013 3TI-3 2005-043T07:15 Feb12 Sat

S8 3 3TI (t) Titan 2005-046T06:54 Feb15 Tue Was T3; inbound 950 km, v= 6.0 km/s, Phase=102 deg

S8 3 Earth OCC Titan 2005-046T07:01 Feb15 Tue Duration = 25 min

S8 3 Sun OCC Titan 2005-046T07:05 Feb15 Tue Duration = 16 min

S8 3 Ring CRX Ascending 2005-047T23:38 Feb16 Wed r=3.6 Rs

S8 3 Periapse 2005-048T00:54 Feb17 Thu r=3.5 Rs, Phase=115 deg

S8 3 3EN (nt) Enceladus 2005-048T03:24 Feb17 Thu outbound 1,179 km, v= 6.6 km/s, Phase=98 deg

S8 3 OTM-014 3TI+3 2005-048T07:16 Feb17 Thu

S8 3 Ring CRX Descending 2005-051T13:40 Feb20 Sun r=30.4 Rs

This list only includes flybys of Titan < 1,000,000 km and icy satellites < 100,000 km. Saturn occultation times computed using 100

mbar pressure surface (Appendix B). 1 Rs = 60330 km.

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CASSINI TOUR EVENT SUMMARY All times are in SCET. For events with nonzero duration, epoch given is start.

Seq Rev Name Event Epoch (SCET) Date DOW Comment

S9 3 S9 Begins 2005-058T00:36 Feb27 Sun Duration = 41 days

S9 4 Apoapse 2005-058T06:20 Feb27 Sun P=20.5 d, i=.3, r=44.3 Rs, Phase=65 deg, LTST=4:20

S9 4 OTM-015 ~APO 2005-061T04:50 Mar02 Wed

S9 4 OTM-016 4EN-3 2005-065T04:35 Mar06 Sun

S9 4 4EN (t) Enceladus 2005-068T09:06 Mar09 Wed was E1; inbound 499 km, v= 6.6 km/s, Phase=43 deg

S9 4 Ring CRX Ascending 2005-068T10:18 Mar09 Wed r=3.6 Rs

S9 4 Periapse 2005-068T11:38 Mar09 Wed r=3.5 Rs, Phase=115 deg

S9 4 4TE (nt) Tethys 2005-068T11:42 Mar09 Wed outbound 82,975 km, v= 6.9 km/s, Phase=64 degS9 4 OTM-017 4EN+3 2005-071T03:20 Mar12 Sat

S9 4 Ring CRX Descending 2005-071T22:13 Mar12 Sat r=30.0 Rs

S9 5 Apoapse 2005-078T17:25 Mar19 Sat P=20.5 d, i=.4, r=44.4 Rs, Phase=66 deg, LTST=4:22

S9 5 OTM-018 ~APO 2005-078T18:19 Mar19 Sat

S9 5 OTM-019 5TI-3 2005-087T02:00 Mar28 Mon

S9 5 5EN (nt) Enceladus 2005-088T20:20 Mar29 Tue inbound 63,785 km, v= 10.1 km/s, Phase=134 deg

S9 5 Ring CRX Ascending 2005-088T22:22 Mar29 Tue r=3.6 Rs

S9 5 Periapse 2005-088T23:26 Mar29 Tue r=3.5 Rs, Phase=114 deg

S9 5 5TI (t) Titan 2005-090T19:55 Mar31 Thu Was T4; outbound 2,523 km, v= 5.9 km/s, Phase=65 deg

S9 5 Ring CRX Descending 2005-090T21:58 Mar31 Thu r=21.3 Rs

S9 5 OTM-020 5TI+3 2005-094T02:22 Apr04 Mon

S9 6 Apoapse 2005-096T23:23 Apr06 Wed P=16.0 d, i=7.0, r=38.0 Rs, Phase=72 deg, LTST=4:50

S10 6 S10 Begins 2005-099T05:15 Apr09 Sat Duration = 35 days

S10 6 OTM-021 ~APO 2005-100T02:00 Apr10 Sun

S10 6 OTM-022 6TI-3 2005-104T02:40 Apr14 Thu

S10 6 Ring CRX Ascending 2005-104T22:11 Apr14 Thu r=2.7 Rs

S10 6 Periapse 2005-104T23:10 Apr14 Thu r=2.6 Rs, Phase=108 deg

S10 6 Earth OCC Ring 2005-104T23:47 Apr14 Thu Duration = 101 min.

S10 6 Sun OCC Ring 2005-104T23:56 Apr14 Thu Duration = 105 min.

S10 6 6MI (nt) Mimas 2005-105T01:20 Apr15 Fri outbound 77,233 km, v= 13.6 km/s, Phase=94 deg

S10 6 Earth OCC Titan 2005-106T19:05 Apr16 Sat Duration = 7 min

S10 6 6TI (t) Titan 2005-106T19:05 Apr16 Sat Was T5; outbound 950 km, v= 6.1 km/s, Phase=127 deg

S10 6 Sun OCC Titan 2005-106T19:06 Apr16 Sat Duration = 8 min

S10 6 Ring CRX Descending 2005-106T19:51 Apr16 Sat r=20.9 Rs

S10 6 OTM-023 6TI+3 2005-110T00:00 Apr20 Wed

S10 7 Apoapse 2005-113T23:10 Apr23 Sat P=18.2 d, i=21.7, r=40.6 Rs, Phase=65 deg, LTST=4:19

S10 7 OTM-024 ~APO 2005-118T23:45 Apr28 Thu

S10 7 7TE (nt) Tethys 2005-122T21:04 May02 Mon inbound 64,990 km, v= 10.0 km/s, Phase=118 deg

S10 7 Ring CRX Ascending 2005-122T23:02 May02 Mon r=3.9 Rs

S10 7 Periapse 2005-123T01:08 May03 Tue r=3.6 Rs, Phase=115 deg

S10 7 Earth OCC Ring 2005-123T02:23 May03 Tue Duration = 97 min.

S10 7 Sun OCC Ring 2005-123T02:51 May03 Tue Duration = 99 min.S10 7 Earth OCC Saturn 2005-123T04:07 May03 Tue Duration = 144 min.

S10 7 Sun OCC Saturn 2005-123T04:38 May03 Tue Duration = 154 min.

S10 7 Earth OCC Ring 2005-123T06:33 May03 Tue Duration = 93 min.

S10 7 Sun OCC Ring 2005-123T07:18 May03 Tue Duration = 94 min.

S10 7 7TI (nt) Titan 2005-124T05:10 May04 Wed outbound 860,004 km, v= 10.2 km/s, Phase=153 deg

S10 7 Ring CRX Descending 2005-125T01:50 May05 Thu r=21.5 Rs

S10 8 Apoapse 2005-132T03:22 May12 Thu P=18.2 d, i=21.9, r=40.6 Rs, Phase=66 deg, LTST=4:22

S11 8 S11 Begins 2005-134T02:50 May14 Sat Duration = 35 days

S11 8 Ring CRX Ascending 2005-141T03:29 May21 Sat r=3.9 Rs

S11 8 Periapse 2005-141T05:37 May21 Sat r=3.6 Rs, Phase=114 deg

S11 8 Earth OCC Ring 2005-141T06:57 May21 Sat Duration = 97 min.

S11 8 8EN (nt) Enceladus 2005-141T07:19 May21 Sat outbound 92,997 km, v= 8.1 km/s, Phase=81 deg

S11 8 Sun OCC Ring 2005-141T07:23 May21 Sat Duration = 99 min.

S11 8 Earth OCC Saturn 2005-141T08:42 May21 Sat Duration = 146 min.

S11 8 Sun OCC Saturn 2005-141T09:09 May21 Sat Duration = 154 min.

S11 8 Earth OCC Ring 2005-141T11:12 May21 Sat Duration = 93 min.

S11 8 Sun OCC Ring 2005-141T11:51 May21 Sat Duration = 95 min.S11 8 Ring CRX Descending 2005-143T05:37 May23 Mon r=21.3 Rs

S11 9 Apoapse 2005-150T08:00 May30 Mon P=18.2 d, i=21.9, r=40.6 Rs, Phase=66 deg, LTST=4:25

S11 9 9TI (nt) Titan 2005-157T18:50 Jun06 Mon inbound 425,973 km, v= 5.8 km/s, Phase=82 deg

S11 9 Ring CRX Ascending 2005-159T08:09 Jun08 Wed r=3.9 Rs

S11 9 Periapse 2005-159T10:20 Jun08 Wed r=3.6 Rs, Phase=114 deg

S11 9 Earth OCC Ring 2005-159T11:48 Jun08 Wed Duration = 98 min.

S11 9 Sun OCC Ring 2005-159T12:09 Jun08 Wed Duration = 99 min.

S11 9 Earth OCC Saturn 2005-159T13:34 Jun08 Wed Duration = 149 min.

S11 9 Sun OCC Saturn 2005-159T13:56 Jun08 Wed Duration = 155 min.

S11 9 Earth OCC Ring 2005-159T16:08 Jun08 Wed Duration = 93 min.

S11 9 Sun OCC Ring 2005-159T16:38 Jun08 Wed Duration = 95 min.

S11 9 Ring CRX Descending 2005-161T09:09 Jun10 Fri r=21.0 Rs

This list only includes flybys of Titan < 1,000,000 km and icy satellites <

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