The majority of the text in this file was extracted from the Cassini
Mission Plan Document, D. Seal, 2003. [JPLD-5564]
The Cassini spacecraft, including the Huygens Probe, was launched on 15
October 1997 using a Titan IV/B launch vehicle with Solid Rocket Motor
Upgrade (SRMU) strap-ons and a Centaur upper stage. The spacecraft used a
6.7-year Venus-Venus-Earth-Jupiter Gravity Assist (VVEJGA) trajectory to
Saturn, during which cruise observations were conducted to check out,
calibrate, and maintain the instruments as well as to perform limited
science. After Saturn Orbit Insertion (SOI) (1 July 2004), the Huygens
Probe separated and, on the third encounter with Titan, entered the
satellite's atmosphere to make in situ measurements during an approximately
150 minute descent (14 January 2005). The Orbiter continued a tour of the
Saturn system until mid-2008 collecting data on the planet and its
satellites, rings, and environment.
After a highly successful Saturn Orbit Insertion (SOI) in June of 2004
and Huygens Probe descent to the surface of Titan in January of 2005,
Cassini went on to complete its four-year tour of Saturn, its rings,
satellites, and magnetosphere via 75 orbits about Saturn, 45 close Titan
flybys, 4 Enceladus flybys, and 9 close flybys of other icy satellites
along with dozens of Saturn, rings, and Titan radio and Solar occultations.
At the end of the very successful prime mission all instruments and major
spacecraft systems were healthy. Due to the highly successful execution
of the prime mission, the vast quantity of new discoveries and overall
quality of science being returned by the Cassini spacecraft, and the
estimated propellant remaining at the conclusion of the prime mission,
NASA Headquarters allocated funding for the development of a 2-year Cassini
extended mission.
At the conclusion of the prime mission tour phase on 30 June 2008, Cassini
initiated a two-year extended mission named the Equinox Mission (EM) to be
completed on 30 September 2010. This mission will feature an additional 28
Titan flybys, twelve close icy satellite flybys, and 64 orbits of Saturn.
The orbit inclination will move from over 70 degrees at the start of the
Equinox mission down to 0 degrees in a little over a year, then back up to
20 degrees in Jan 2010, and again in July 2010. There are eight Enceladus
flybys along with single flybys of Rhea, Mimas, Dione, and Helene. The
Enceladus flybys are designed to provide close flybys to provide the best
views of the plume expulsions near the South Pole area. In addition, there
are 22 non-targeted, distant flybys of icy satellites. Titan flybys
continue to map the surface of Titan. The scientific intensity and priority
of this phase, as judged by the project and by HQ, is of the same level as
that of the prime mission.
The proposed second extended mission, temporarily called the Extended-
extended mission (XXM) or also the Solstice Mission (SM), is a seven-year
mission that would commence on 30 September 2010 and end on 15 September
2017. The SM features 54 Titan flybys, 23 close icy satellite flybys (which
include 11 Enceladus flybys), and 156 orbits of Saturn. The mission will
continue to explore the features of the Saturnian system such as the rings,
the magnetosphere, and the icy satellites, address new questions raised by
Cassini's Prime and Equinox missions, as well as observing seasonal changei
in the Saturnian system.
The Cassini Orbiter (CO) was a three-axis stabilized spacecraft equipped
with one high gain antenna (HGA) and two low gain antennas (LGAs), three
Radioisotope Thermoelectric Generators (RTGs) for power, main engines,
attitude thrusters, and reaction wheels. It carried twelve orbiter
instruments designed to carry out 27 diverse science investigations. The
Huygens Probe (HP) was equipped with six instruments designed to study the
atmosphere and surface of Titan. It entered the upper atmosphere protected
by a heat shield, then deployed parachutes to descend slowly to the surface
from an altitude of about 200 km. The instruments, with acronym and
Principal Investigator (PI) or Team Leader (TL), are summarized below:
Instrument Acronym PI/TL
----------------------------------------------- ------------
Orbiter:
Cassini Plasma Spectrometer CAPS Young
Cosmic Dust Analyzer CDA Srama
Composite Infrared Spectrometer CIRS Flasar
Ion and Neutral Mass Spectrometer INMS Waite
Imaging Science Subsystem ISS Porco
Magnetometer MAG Dougherty
Magnetospheric Imaging Instrument MIMI Krimigis
Cassini Radar RADAR Elachi
Radio and Plasma Wave Science RPWS Gurnett
Radio Science Subsystem RSS Kliore
Ultraviolet Imaging Spectrograph UVIS Esposito
Visible and Infrared Mapping Spectrometer VIMS Brown
Probe:
Aerosol Collector and Pyrolyser ACP Israel
Descent Imager Spectral Radiometer DISR Tomasko
Doppler Wind Experiment DWE Bird
Gas Chromatograph Mass Spectrometer GCMS Niemann
Huygens Atmospheric Structure Instrument HASI Fulchignoni
Surface Science Package SSP Zarnecki
Mission Phases
==============
LAUNCH 1997-10-15 to 1997-10-17
1997-288 to 1997-290
------
Cassini successfully lifted-off from the Cape Canaveral Air Station complex
40 on 15 October 1997 at 08:55 UTC. The solid rocket motors burned from
liftoff to separation at 2 min 23 sec at an altitude of 68,300 m. Stage 1
ignition began at 2 min 11 sec at an altitude of 58,500 m, and Stage 2
ignition (and Stage 1 separation) occurred at 5 min 23 sec after liftoff at
167,300 m. During the first three minutes and 27 seconds of flight, the
payload fairing shrouded the spacecraft, protecting it from direct solar
illumination.
The Centaur upper stage separated from the launch vehicle at 9 min 13 sec
at 206,700 m. The first Centaur burn began at 9 min 13 sec and lasted
approximately two minutes. This burn placed the Cassini spacecraft into an
elliptical, 170 km by 445 km parking orbit with an inclination of about 30
degrees. After 17 minutes in the parking orbit, the Centaur fired again and
launched Cassini toward Venus en route to Saturn. The injection C3 was 16.6
km^2/s^2.
Immediately after separation from the Centaur (date?), the spacecraft's
Attitude and Articulation Control Subsystem (AACS) pointed the HGA toward
the Sun to achieve a thermally safe attitude in which the HGA served as an
umbrella for the remainder of the spacecraft. X-band uplink and downlink
was established through the LGAs, the Radio and Plasma Wave Science (RPWS)
Langmuir Probe was deployed, instrument replacement heaters and main engine
oxidizer valve heaters were turned on, and the Stellar Reference Unit
(SRU), Imaging Science Subsystem (ISS), and Visible and Infrared Mapping
Spectrometer (VIMS) decontaminations were started.
TCM 1 1997-10-18 to 1997-11-14
1997-291 to 1997-318
-----
The Trajectory Correction Maneuver 1 (TCM 1) phase comprised four one-week
sequences. During most of the TCM 1 phase, the spacecraft was in a
relatively quiescent state with the HGA pointed toward the Sun. Telemetry
downlinked by the spacecraft was utilized to make an initial
characterization of the spacecraft and to assess whether its various
subsystems survived the launch. Deployment, decontamination, tank heating,
and AACS checkout activities were started.
Before the maneuver itself, the fuel and oxidizer tanks were heated in
order to avoid an irreversible overpressure in the propellant lines. If
the tanks fully pressurized before the spacecraft passed through the peak
temperature regime, then (when the spacecraft did enter the maximum thermal
environment) the tank pressure would climb without there being a way to
bring it back down, possibly causing an overpressure.
TCM 1 was an Earth injection clean-up maneuver placed at 25 days after
launch. TCM 1 was executed using the main engine with a delta-V magnitude
of 2.8 m/s. The burn sequence included holding the spacecraft off-Sun after
burn completion to allow the spacecraft heating to be characterized in a
relatively benign environment.
INTERPLANETARY CRUISE 1997-11-14 to 1999-11-07
1997-318 to 1999-311
---------------------
The Interplanetary Cruise Phase extended from 14 November 1997 to 7
November 1999. It consisted of three subphases: Venus 1 Cruise,
Instrument Checkout 1, and Venus 2 - Earth Cruise. During most of this
phase, Cassini's proximity to the Sun constrained the spacecraft to remain
Sun-pointed, and communications were conducted using the Low Gain Antennas.
The downlink capability of the LGAs at large spacecraft-Earth ranges was
very limited. Between 30 and 150 days after launch, for example, the
downlink data rate decreased from 948 to 20 bps.
Beginning on 28 December 1998, the spacecraft approached opposition and the
HGA could be pointed towards Earth for a period of 25 days while the Probe
equipment temperature remained within the required range. This provided a
high data rate window during which checkout activities could be
accomplished.
VENUS 1 CRUISE 1997-11-14 to 1998-09-13
1997-318 to 1998-256
--------------
The Venus 1 Cruise subphase started on 14 November 1997 and continued
through 13 September 1998. The subphase encompassed sequences C5 through C9
and included two TCMs, one planetary swingby, and three switches between
LGA1 and LGA2. Most of the period was dedicated to engineering and
instrument maintenance activities.
VENUS 1 ENCOUNTER 1998-04-26
1998-116
The first Venus encounter occurred on 26 April 1998. The spacecraft
approached Venus from a sunward direction, and closest approach occurred
just after the spacecraft entered the Sun's shadow for a period of about 15
minutes. At closest approach, the altitude was 284 km, with a velocity
relative to Venus of 11.8 km/s. The spacecraft was occulted from Earth for
about 2 hours. The Earth occultation zone started about 15 minutes after
the spacecraft left the Sun occultation zone. Accuracy for the Venus flyby
was assured by using two TCMs (Trajectory Correction Maneuvers), 60 and 20
days before closest approach, and a clean-up maneuver 20 days after the
flyby.
INSTRUMENT CHECKOUT 1 1998-09-14 to 1999-03-14
1998-257 to 1999-073
---------------------
The Instrument Checkout 1 subphase (ICO-1) started on 14 September 1998,
continued through 14 March 1999, and consisted of sequences C10-C13. This
subphase was characterized by the opposition that occurred on 9 January
1999, which allowed use of the HGA for downlink since the Earth and Sun
were nearly aligned as seen from Cassini.
All instruments scheduled checkout activities within the 25 day period
centered on opposition. This was the first opportunity since launch to
exercise and check the status of most instruments outside of routine
maintenance. The 'Quiet Test', for example, allowed each instrument to
monitor other instruments as they turned on and off and provided valuable
insight into how to integrate science observations during the Saturn tour.
During instrument checkout activities, the spacecraft autonomously went
into a safe state. Accumulating star position errors from the slow turn
required to keep the Sun on the -x-axis triggered AACS fault protection.
Most of the instrument checkout activities were rescheduled after a 10 day
safing period. Those that were not completed were rescheduled for the ICO-2
subphase during Outer Cruise.
VENUS 2 - EARTH CRUISE 1999-03-15 to 1999-11-07
1999-074 to 1999-311
----------------------
The Venus 2 - Earth Cruise subphase started on 15 March 1999, 45 days prior
to the second Venus flyby, and continued through 7 November 1999, which was
82 days after the Earth flyby. The subphase encompassed sequences C13
through C16, and included seven scheduled TCMs, two planetary swingbys, and
25 science activities in addition to normal engineering activities. Science
activities included maintenance, calibration, checkout, and science
observations using all of the Cassini instruments except INMS and CIRS.
VENUS 2 ENCOUNTER 1999-06-24
1999-175
TCM-7 was executed 37 days before the Venus 2 Encounter. TCM-8 was
scheduled 21 days prior to Venus 2, but it was canceled. DSN (Deep Space
Network) coverage increased from one to three passes per day in support of
the flyby.
EARTH ENCOUNTER 1999-08-18
1999-230
The Earth flyby occurred 55 days after the Venus 2 flyby. The spacecraft
approached the Earth from approximately the direction of the Sun. Closest
approach occurred right after the spacecraft entered the Sun occultation
zone. The occultation lasted approximately 30 minutes. The altitude at
closest approach was 1175 km, with an Earth-relative velocity of 19.0 km/s.
Trajectory correction maneuvers took place 43, 30, 15 and 6.5 days before
closest approach, and a clean-up maneuver was executed 13 days after the
flyby. Continuous DSN coverage began at the Venus 2 flyby and continued
through the Earth flyby. A week after the Earth Encounter, DSN coverage
dropped to one pass every two days.
Five instruments conducted observations as Cassini passed through the
Earth's magnetotail.
OUTER CRUISE 1999-11-08 to 2002-07-07
1999-312 to 2002-188
------------
The Outer Cruise Phase consisted of four subphases: HGA Transition,
Instrument Checkout 2, Jupiter Cruise, and Quiet Cruise. The Outer Cruise
phase extended from 8 November 1999 (when the spacecraft reached a Sun
range of 2.7 AU) to 7 July 2002 (about two years before Saturn Orbit
Insertion). At 2.7 AU (1 February 2000), the HGA began continuous Earth-
pointing. The one planetary encounter in this phase was the flyby of
Jupiter in December 2000. Science at Jupiter was an opportunity to test
Saturn observation strategies with HGA data rates.
HIGH GAIN ANTENNA TRANSITION 1999-11-08 to 2000-05-06
1999-312 to 2000-127
----------------------------
This subphase included sequences C17 to C19, operation of ISS and VIMS
decontamination heaters, CDA dust calibrations, and Magnetosphere and
Plasma Science (MAPS) observations after the HGA was pointed toward Earth.
During the initial part of the subphase (C17 and part of C18),
telecommunications were via LGA1, and the spacecraft was at the farthest
distance from Earth before transitioning to the HGA for regular use.
Therefore, data rates were very low and activities were kept to a minimum.
C17 included standard maintenance and one Periodic Engineering Maintenance
(PEM) activity. Activities during the LGA1 portion of C18 included a
Periodic Instrument Maintenance (PIM); observations by ISS, VIMS, and UVIS
of the asteroid Masursky near closest approach (1,634,000 km); and ISS dark
frame calibration images directly following the Masursky observations.
The HGA was turned toward Earth for regular use on 1 February 2000, during
C18. Several activities took place during the rest of C18, using the
greater telemetry capabilities available with the HGA: playback of the
Masursky data and ISS dark frames, a Probe checkout, a Huygens Probe S-band
Relay to Cassini Test, a Telemetry-Ranging Interference Test, MAG
calibrations, and a PEM. Regular MAPS observations by CAPS, CDA, MAG, MIMI,
and RPWS began within a few days after transitioning to the HGA.
The first 6 weeks of C19 were used for a checkout of new Flight Software.
The AACS version A7 software was uploaded near the beginning of this
period, and the first 2 weeks were devoted to AACS tests. The next 4 weeks
were originally scheduled for CDS tests of version V7.0. However, these
tests were delayed to late July and August of 2000 to allow time for
additional regression testing. During the AACS checkout period, MAPS
activity ceased. Several activities took place during the last 3 weeks of
C19: resumption of MAPS observations, three RSS activities (HGA pattern
calibration, HGA boresight calibration, and USO characterization), CIRS
Cooler Cover release, and a PIM.
A few days before the end of C19, the command loss timer setting was
increased slightly, to account for the 10-day period at the beginning of
C20 during which superior conjunction made commanding problematic.
INSTRUMENT CHECKOUT 2 2000-05-06 to 2000-11-05
2000-127 to 2000-310
---------------------
The second instrument checkout subphase (ICO-2) was scheduled from 6 May
2000 to 5 November of 2000, after the Spacecraft Office had completed its
engineering checkout activities. ICO-2 included instrument checkout that
required reaction wheel stability and any instrument checkouts that were
not successfully completed during ICO-1. But the CDS Flight Software V7
uplink and checkout, which was delayed from March, was rescheduled to late
July through early September 2000, causing many ICO-2 activities to be
compressed into a shorter and more intense period. Some activities were
postponed until after the Jupiter observations were completed in 2001.
The subphase began with a superior conjunction which precluded early
science or engineering activities. MAPS instruments remained on; but data
return was not attempted during conjunction. Two TCMs were scheduled for
Jupiter targeting, in June and September.
Engineering activities included the continuous use of reaction wheels and,
beginning on 1 October 2000, dual Solid State Recorders (SSRs). There were
no scheduled instrument PIMs during ICO-2 since all instruments had other
activities that accomplished this function. Other engineering activities
included two Reaction Wheel Assembly (RWA) friction tests, two PEMs, and an
SRU calibration.
Science activities began with the MAPS instruments continuing from C19. New
flight software was loaded for eight instruments in late May, and a CDA
software update was done in September. New Quiet Tests, while operating on
reaction wheels, were done in July for most instruments. RSS Quiet Tests
were done in September, and RADAR related tests were done in late June. A
Probe checkout occurred in late July.
Spacecraft turns were done for RADAR observations of the Sun and Jupiter in
June and again in September. The star Alpha Piscis Austrinus (Fomalhaut)
was also observed in September by VIMS with ISS and UVIS doing ride-along
science. No other science turns were scheduled until October. On 1 October,
science began using a repeating 5-day template to gather Jupiter science.
This involved 11 turns in a 5 day period, including two downlinks. The
turns in the 5-day template involved 4 orientations:
Orbiter Remote Science (ORS) boresights to Jupiter,
Z axis parallel to ecliptic
HGA to Sun, rolling about Z axis
Probe to Sun, rotating about X axis
HGA to Earth, Probe offset from Sun for CDA, not
rotating, downlink orientation
JUPITER CRUISE 2000-11-05 to 2001-04-30
2000-310 to 2001-120
--------------
The Jupiter Cruise subphase extended from 6 November 2000 to 29 April 2001
and included sequences C23 to C25. However Jupiter remote sensing
observations actually began on 1 October 2000, in C22.
JUPITER ENCOUNTER 2000-12-30
2000-365
The Jupiter flyby occurred on 30 December 2000 at an altitude of 9.7
million km. This gravity assist rotated the trajectory 12 deg and increased
the heliocentric velocity by 2 km/s. The Jupiter relative speed at closest
approach was 11.6 km/s. At closest approach, Jupiter filled the Narrow
Angle Camera (NAC) field of view. Extensive Jupiter science was performed
which required additional DSN support: up to two passes every five days,
and a maximum of one pass every 30 hours in the 10 days on either side of
closest approach. Science at Jupiter was an opportunity to test how to
build and execute viable Saturn sequences.
A problem with the RWAs occurred on 16 December 2000. Increased friction on
one of the wheels caused the spacecraft to switch autonomously to the
Reaction Control Subsystem (RCS) for attitude control. With the switch to
RCS, hydrazine usage increased. Two of four joint CAPS-Hubble Space
Telescope observations, a Jupiter North-South map, the Himalia 'flyby', and
a UVIS torus observation were all executed on RCS before the sequence was
terminated on 19 December 2000. MAPS data continued to be recorded at a
reduced rate. All other planned science activities were suspended. After
tests, RWA operation was resumed for attitude control on 22 December, with
the wheels biased away from low RPM regions. The sequence was restarted on
29 December.
QUIET CRUISE 2001-04-30 to 2002-07-08
2001-120 to 2002-189
------------
Quiet Cruise was a 14 month subphase that started at the end of Jupiter
Cruise and ended two years before SOI. During this subphase, routine
maintenance, engineering, and navigation functions were carried out. One
Gravitational Wave Experiment (GWE) was conducted in December 2001, and one
Solar Conjunction Experiment (SCE) was conducted in June 2002.
SCIENCE CRUISE 2002-07-08 to 2004-06-10
2002-189 to 2004-162
--------------
SPACE SCIENCE 2002-07-08 to 2004-01-11
2002-189 to 2004-011
The Space Science subphase began on 8 July 2002 and ran through 11 January
2004. TCMs 18 and 19, two GWEs (December 2002 and December 2003) and one
SCE (June-July 2003) were conducted.
APPROACH SCIENCE 2004-01-12 to 2004-06-10
2004-012 to 2004-162
The Approach Science subphase began six months before SOI and ended three
weeks before SOI, when the spacecraft was approaching Saturn at a rate of 5
kilometers per second. Most of the activities during the Approach Science
subphase were Saturn science observations and preparation for the Phoebe
flyby, SOI, and Tour operations.
The reaction wheels were turned on at the beginning of the subphase to
provide a more stable viewing platform. By this point, the imaging
instruments had begun atmospheric imaging, and making long-term atmospheric
movies. CIRS began long integrations of Saturn's disk. At SOI - 4 months,
Saturn filled one third of the NAC field of view and one half of the CIRS
Far Infrared (FIR) field of view.
The Saturn approach was made toward the morning terminator at a phase angle
of about 75 degrees; VIMS gathered data on the temperature difference
across the terminator. UVIS scans of the Saturn System began 3-4 months
before SOI. Fields, particles, and waves instruments collected solar wind
information and recorded Saturn emissions as the spacecraft neared the
planet. Science data gathered during this period was stored on the SSR and
transmitted back to Earth. Daily DSN tracking coverage began 90 days before
SOI.
The Phoebe approach TCM took place on 27 May 2004, 15 days before Phoebe
closest approach.
TOUR PRE-HUYGENS 2004-06-11 to 2004-12-24
2004-163 to 2004-359
----------------
The Tour Pre-Huygens Phase extended from the Phoebe Encounter through
Saturn Orbit Insertion to separation of the Huygens Probe from the Cassini
Orbiter.
PHOEBE ENCOUNTER 2004-06-11
2004-163
The flyby of Phoebe occurred on 11 June 2004, 19 days before SOI. At
closest approach (19:33 UTC) the spacecraft was 2000 km above the surface.
SATURN ORBIT INSERTION 2004-07-01
2004-183
During Saturn Orbit Insertion (SOI) on 1 July 2004, the spacecraft made its
closest approach to the planet's surface during the entire mission at an
altitude of only 0.3 Saturn radii (18,000 km). Due to this unique
opportunity, the approximately 95-minute SOI burn (633 m/s total delta-V),
required to place Cassini in orbit around Saturn, was executed earlier than
its optimal point centered around periapsis, and instead ended near
periapsis, allowing science observations immediately after burn completion.
The SOI maneuver placed the spacecraft in an initial orbit with a periapsis
radius of 1.3 Rs, a period of 148 days, and an inclination of 16.8 degrees.
After the burn, the spacecraft was turned to allow the ORS instruments to
view the Saturn inner rings that were not in shadow. After periapsis, the
trajectory just grazed the occultation zones behind the planet with the
Earth and Sun being occulted by Saturn. After communication with Earth was
re-established, the spacecraft remained on Earth pointed for nine hours to
play back engineering and science data and to give ground personnel time to
evaluate the spacecraft status.
After SOI a pair of cleanup maneuvers was used to correct for errors in the
SOI burn. The first was immediately before superior conjunction, at SOI + 3
days, and the second was after conjunction at SOI + 16 days.
Probe checkouts were scheduled at SOI + 14 days, Probe Release Maneuver
(PRM) + 4 days, and ten days before separation.
The partial orbit between SOI and the first apoapsis was designated orbit
0. The next three orbits were designated a, b, and c.
TITAN A ENCOUNTER 2004-10-26
2004-300
TITAN B ENCOUNTER 2004-12-13
2004-348
HUYGENS DESCENT 2004-12-24 to 2005-01-14
2004-359 to 2005-014
---------------
HUYGENS PROBE SEPARATION 2004-12-24
2004-359
The probe was released from the Orbiter on 24 December 2004, 11 days after
the second Titan flyby (orbit b). Two days after the Probe was released,
the Orbiter executed a deflection maneuver to place itself on the proper
trajectory for the third encounter.
TITAN C HUYGENS 2005-01-14
2005-014
During the third flyby (orbit c), on 14 January 2005, the Huygens Probe
transmitted data to the orbiter for approximately 150 minutes during its
descent through the atmosphere to the surface.
Because the Orbiter was looking at Titan through most of the corresponding
Goldstone tracking pass, DSN support on this day was primarily through the
70-meter antennas at the Canberra and Madrid tracking complexes. While
approaching Titan, the Orbiter made its last downlink transmission (to the
Madrid station, DSS 63) before switching to Probe relay mode. The Orbiter
then turned nearly 180 degrees to point its HGA at the predicted Probe
impact point, and the Probe Support Avionics (PSA) were configured to
receive data from the Probe. Some Orbiter instruments were put into a low
power state to provide additional power for the PSA. The data from the
Probe were transmitted at S band in two separate data streams, and both
were recorded on each SSR. Following completion of the predicted descent
(maximum 150 minutes), the Orbiter listened for Probe signals for an
additional 30 minutes, in case they continued after landing.
When data collection from the Probe was completed, those data were write
protected on each SSR. The spacecraft then turned to view Titan with
optical remote sensing instruments until about one hour after closest
approach for a total observing window of TBD.
The Orbiter then turned the HGA towards Earth and began transmitting the
recorded Probe data to the Canberra 70-m antenna. The complete, four-fold
redundant set of Probe data was transmitted twice, and its receipt
verified, before the write protection on that portion of the SSR was lifted
by ground command. A second playback, including all of the Probe data and
the Orbiter instrument observations, was returned over the subsequent
Madrid 70-meter tracking pass, which was longer and at higher elevation
angles.
TOUR 2005-01-14 to 2008-06-30
2005-014 to 2008-182
----
The Tour Phase of the mission began at completion of the Huygens Probe and
Orbiter-support playback and ended on 30 June 2008. It included dozens of
satellite encounters and extended observations of Saturn, its rings, and
its environment of particles and fields.
TOUR SEQUENCE BOUNDARIES
The table below shows spacecraft background sequences, orbit revolution,
start epoch (including day-of-year in a separate column), and the length of
the sequence. For completeness, all 'S' sequences are listed even though
the first seven covered times before the Tour phase. Each orbit about
Saturn was assigned a revolution identifier starting with a, b, and c, and
then numerically ascending from 3 to 74; these were not synchronous with
sequences, some of which covered only partial orbits. Full orbits began
and ended at apoapsis; the partial orbit from SOI to the first apoapsis was
orbit 0.
Sequence Rev Epoch (SCET) DOY Duration
In days
-------- --- ----------------- --- --------
S1 - 2004-May-15 00:00 136 35
S2 0 2004-Jun-19 01:38 171 42
S3 0 2004-Jul-30 23:05 212 43
S4 a 2004-Sep-11 19:10 255 35
S5 a 2004-Oct-16 18:40 290 28
S6 a 2004-Nov-13 16:59 318 33
S7 b 2004-Dec-16 15:03 351 37
S8 c 2005-Jan-22 10:38 022 36
S9 3 2005-Feb-27 00:36 058 41
S10 6 2005-Apr-09 05:15 099 35
S11 8 2005-May-14 02:50 134 35
S12 10 2005-Jun-18 01:34 169 42
S13 12 2005-Jul-29 22:36 210 32
S14 14 2005-Aug-30 21:53 242 39
S15 16 2005-Oct-08 15:57 281 35
S16 17 2005-Nov-12 17:01 316 35
S17 19 2005-Dec-17 14:21 351 42
S18 20 2006-Jan-28 11:23 028 42
S19 22 2006-Mar-11 00:35 070 42
S20 23 2006-Apr-22 05:15 112 42
S21 24 2006-Jun-03 02:39 154 42
S22 26 2006-Jul-15 00:06 196 35
S23 27 2006-Aug-18 22:06 230 39
S24 29 2006-Sep-26 19:53 269 26
S25 31 2006-Oct-22 18:26 295 33
S26 33 2006-Nov-24 16:30 328 42
S27 36 2007-Jan-05 13:50 005 43
S28 39 2007-Feb-17 10:52 048 40
S29 41 2007-Mar-29 08:04 088 37
S30 44 2007-May-04 22:00 124 37
S31 46 2007-Jun-11 03:10 162 33
S32 48 2007-Jul-14 01:06 195 29
S33 49 2007-Aug-11 23:20 223 42
S34 50 2007-Sep-22 20:51 265 40
S35 51 2007-Nov-01 18:40 305 42
S36 54 2007-Dec-13 16:15 347 39
S37 56 2008-Jan-21 13:35 021 26
S38 59 2008-Feb-16 11:51 047 36
S39 62 2008-Mar-23 01:50 083 27
S40 65 2008-Apr-19 07:18 110 42
S41 70 2008-May-31 04:27 152 35
SATELLITE ENCOUNTER SUMMARY
This table summarizes the Cassini Orbiter satellite encounters; for
completeness, all recognized encounters are included even though the first
eight preceded the Tour phase. Rev identifies the orbit revolution as
defined above. The three character ID for the encounter is in the second
column; an appended asterisk (*) denotes a non-targeted encounter. The
target, date and time, and day-of-year are in the next three columns.
Altitude above the surface at closest approach, sense of the encounter
(whether on the inbound or outbound leg of an orbit), relative velocity at
closest approach, and phase angle at closest approach round out the
columns.
Rev Name Satellite Epoch (SCET) DOY Alt in/ Speed Phase
km out km/s deg
---- ----- --------- ---------------- --- --- --- ----- ----
0 0PH Phoebe 2004-Jun-11 19:33 163 1997 in 6.4 25
0 0MI* Mimas 2004-Jul-01 00:30 183 76424 in 22.3 80
0 0TI* Titan 2004-Jul-02 09:30 184 338958 out 8.3 67
a aTI Titan 2004-Oct-26 15:30 300 1200 in 6.1 91
b bTI Titan 2004-Dec-13 11:37 348 2358 in 6 98
b bDI* Dione 2004-Dec-15 02:11 350 81592 in 5.3 93
c cIA* Iapetus 2005-Jan-01 01:28 001 64907 in 2.1 106
c cTI Titan 2005-Jan-14 11:04 014 60000 in 5.4 93
3 3TI Titan 2005-Feb-15 06:54 046 950 in 6 102
3 3EN* Enceladus 2005-Feb-17 03:24 048 1179 out 6.6 98
4 4EN Enceladus 2005-Mar-09 09:06 068 499 in 6.6 43
4 4TE* Tethys 2005-Mar-09 11:42 068 82975 out 6.9 64
5 5EN* Enceladus 2005-Mar-29 20:20 088 63785 in 10.1 134
5 5TI Titan 2005-Mar-31 19:55 090 2523 out 5.9 65
6 6MI* Mimas 2005-Apr-15 01:20 105 77233 out 13.6 94
6 6TI Titan 2005-Apr-16 19:05 106 950 out 6.1 127
7 7TE* Tethys 2005-May-02 21:04 122 64990 in 10 118
7 7TI* Titan 2005-May-04 05:10 124 860004 out 10.2 153
8 8EN* Enceladus 2005-May-21 07:19 141 92997 out 8.1 81
9 9TI* Titan 2005-Jun-06 18:50 157 425973 in 5.8 82
10 10TI* Titan 2005-Jun-22 12:27 173 920423 in 3.7 65
11 11EN Enceladus 2005-Jul-14 19:57 195 1000 in 8.1 43
12 12MI* Mimas 2005-Aug-02 03:52 214 45112 in 6.5 83
12 12TI* Titan 2005-Aug-06 12:33 218 841452 out 3.8 62
13 13TI Titan 2005-Aug-22 08:39 234 4015 out 5.8 42
14 14TI Titan 2005-Sep-07 07:50 250 950 out 6.1 84
15 15TE* Tethys 2005-Sep-24 01:29 267 33295 out 7.7 76
15 15TI* Titan 2005-Sep-24 22:01 267 910272 out 10.7 148
15 15HY Hyperion 2005-Sep-26 01:41 269 990 out 5.6 45
16 16TI* Titan 2005-Oct-10 22:20 283 777198 in 9.7 65
16 16DI Dione 2005-Oct-11 17:58 284 500 in 9 66
16 16EN* Enceladus 2005-Oct-12 03:29 285 42635 out 6.6 75
17 17TI Titan 2005-Oct-28 03:58 301 1446 in 5.9 105
18 18RH Rhea 2005-Nov-26 22:35 330 500 in 7.3 87
19 19EN* Enceladus 2005-Dec-24 20:23 358 97169 in 6.9 133
19 19TI Titan 2005-Dec-26 18:54 360 10429 out 5.6 67
20 20TI Titan 2006-Jan-15 11:36 015 2042 in 5.8 121
21 21TI Titan 2006-Feb-27 08:20 058 1812 out 5.9 93
22 22TI Titan 2006-Mar-18 23:58 077 1947 in 5.8 148
22 22RH* Rhea 2006-Mar-21 07:01 080 85935 out 5.3 136
23 23TI Titan 2006-Apr-30 20:53 120 1853 out 5.8 121
24 24TI Titan 2006-May-20 12:13 140 1879 in 5.8 163
25 25TI Titan 2006-Jul-02 09:12 183 1911 out 5.8 148
26 26TI Titan 2006-Jul-22 00:25 203 950 in 6 105
27 27TI* Titan 2006-Aug-18 17:48 230 339190 out 4.8 121
28 28TI Titan 2006-Sep-07 20:12 250 950 in 6 45
28 28EN* Enceladus 2006-Sep-09 20:00 252 39842 out 10.3 116
29 29TI Titan 2006-Sep-23 18:52 266 950 in 6 90
30 30TI Titan 2006-Oct-09 17:23 282 950 in 6 81
31 31TI Titan 2006-Oct-25 15:51 298 950 in 6 25
32 32EN* Enceladus 2006-Nov-09 01:48 313 94410 out 14.1 27
33 33DI* Dione 2006-Nov-21 02:32 325 72293 out 12.3 144
33 33TI* Titan 2006-Nov-25 13:57 329 930525 out 4.5 114
35 35TI Titan 2006-Dec-12 11:35 346 950 in 6 124
36 36TI Titan 2006-Dec-28 10:00 362 1500 in 5.9 62
37 37TI Titan 2007-Jan-13 08:34 013 950 in 6 53
38 38TI Titan 2007-Jan-29 07:12 029 2776 in 5.8 73
39 39TI Titan 2007-Feb-22 03:10 053 953 out 6.3 161
40 40TI Titan 2007-Mar-10 01:47 069 956 out 6.3 149
41 41TI Titan 2007-Mar-26 00:21 085 953 out 6.3 144
42 42TI Titan 2007-Apr-10 22:57 100 951 out 6.3 137
43 43TI Titan 2007-Apr-26 21:32 116 951 out 6.3 130
44 44TI Titan 2007-May-12 20:08 132 950 out 6.3 121
45 45TE* Tethys 2007-May-26 20:57 146 97131 in 11.7 75
45 45TI Titan 2007-May-28 18:51 148 2425 out 6.1 114
46 46TI Titan 2007-Jun-13 17:46 164 950 out 6.3 107
47 47TE* Tethys 2007-Jun-27 19:53 178 16166 in 10.1 90
47 47MI* Mimas 2007-Jun-27 22:56 178 89730 in 16.2 110
47 47EN* Enceladus 2007-Jun-28 01:15 179 90769 out 9.4 55
47 47TI Titan 2007-Jun-29 17:05 180 1942 out 6.2 96
48 48TI Titan 2007-Jul-19 00:39 200 1302 in 6.2 34
49 49TE* Tethys 2007-Aug-29 11:21 241 48324 in 4.7 104
49 49RH* Rhea 2007-Aug-30 01:26 242 5098 out 6.7 46
49 49TI Titan 2007-Aug-31 06:34 243 3227 out 6.1 87
49 49IA Iapetus 2007-Sep-10 12:33 253 1000 out 2.4 65
50 50DI* Dione 2007-Sep-30 06:27 273 56523 in 5.6 47
50 50EN* Enceladus 2007-Sep-30 10:53 273 88174 in 6.1 99
50 50TI Titan 2007-Oct-02 04:48 275 950 out 6.3 67
51 51TI* Titan 2007-Oct-22 00:47 295 455697 in 4.1 29
52 52RH* Rhea 2007-Nov-16 19:52 320 78360 in 9.1 148
52 52TI Titan 2007-Nov-19 00:52 323 950 out 6.3 51
53 53MI* Mimas 2007-Dec-03 05:28 337 79272 in 14.8 138
53 53TI Titan 2007-Dec-05 00:06 339 1300 out 6.3 70
54 54TI Titan 2007-Dec-20 22:56 354 953 out 6.3 61
55 55TI Titan 2008-Jan-05 21:26 005 949 out 6.3 37
57 57TI* Titan 2008-Jan-22 21:06 022 860776 in 4.5 70
59 59TI Titan 2008-Feb-22 17:39 053 959 out 6.4 30
61 61TI* Titan 2008-Mar-10 19:15 070 922539 in 6.3 123
61 61EN Enceladus 2008-Mar-12 19:05 072 995 in 14.6 56
62 62TI Titan 2008-Mar-25 14:35 085 950 out 6.4 21
64 64MI* Mimas 2008-Apr-11 09:38 102 95428 in 16.9 137
66 66TI* Titan 2008-Apr-26 18:22 117 780589 in 5.5 94
67 67TI Titan 2008-May-12 10:09 133 950 out 6.4 35
69 69TI Titan 2008-May-28 08:33 149 1316 out 6.3 23
72 72TI* Titan 2008-Jun-13 04:17 165 372240 in 5.9 89
74 74EN* Enceladus 2008-Jun-30 08:07 182 99092 in 21.6 66
END OF PRIME MISSION 2008-06-30
2008-182
--------------------
EXTENDED MISSION 2008-07-01 to 2010-09-29
2008-183 to 2010-272
----------------
The Cassini prime mission was the most complex gravity-assist tour ever
flown. The extended mission maintains this level of design and navigational
complexity in order to meet and balance the myriad of disparate scientific
objectives requested by the Cassini discipline working groups within the
2.25-year time frame. As a result, compared to the prime mission, the EM
trajectory clearly meets or exceeds the intensity of scientific
opportunities. The two-year extension consists of 28 close Titan flybys,
twelve close icy satellite flybys (of which eight are of Enceladus), 64
orbits around Saturn, and dozens more radio and Solar occultations by
Saturn, its rings, and Titan.
The EM begins at high inclination, where the prime mission left off, with
the apoapsis of its orbit oriented nearly sunward. This geometry is
maintained for nine months for continued in-situ study of Saturn's auroral
region, complementing incomplete observations made at the end of the prime
mission. Also, these high inclinations allowed for high priority stellar
occultations by the main rings, particularly the very dense B ring. Since
one of the ring-plane crossings of this orbit geometry was near Enceladus,
it was also possible to insert three low Enceladus flybys during this phase
while meeting the other objectives. Lastly, the Titan flybys during this
high inclination phase were designed to obtain a mid-northern latitude
Titan radio occultation and a high quality groundtrack over the Huygens
landing site. This first phase completes with a short Titan-Titan
'Pi-transfer' phase, with the first encounter on one side of Titan's orbit
and the second encounter one-half of one orbit later, on the opposite side
of Titan's orbit. This creative strategy was implemented by the Cassini
tour designers as a highly efficient method to transfer the orbit from one
side of Saturn to another, speeding up the exploration of the environment
compared to a more conventional, encounter-by-encounter rotation.
The second major phase of the EM takes place over six months in the poorly
sampled 'dusk sector' of Saturn, i.e. the side outward from Saturn's dusk
terminator. This phase contains the Saturnian equinox in mid-August 2009,
and is Cassini's only chance to study this infrequent geometric event,
as it only occurs every 15 years. During this equinox viewing phase,
Cassini's orbit inclination is slowly reduced, offering a generous variety
of observation geometries for Saturn's rings, where the bulk of the
equinox-related objectives are focused. In addition, Titan flyby
geometries allow for key high-resolution radar mapping and Titan
occultations.
The third major phase is dominated by equatorial orbits and icy satellite
encounters. The fourth through seventh Enceladus encounters occur here, as
well as close flybys of Mimas, Dione, Rhea, and Helene (a Dione coorbital).
Two of the Enceladus encounters, E7 and E9, are designed to pass deep within
the plume emanating from the southern polar region should continuing safety
analyses permit. In addition, two high quality horizontal (ansa to ansa)
ring occultations, long Saturn observation opportunities, a Titan wake
crossing, and mid-northern latitude Saturn occultations are included in
this icy satellite and ansa-to-ansa occultation phase. The final phase
of the Equinox Mission is several months long, and contains a series of
short Titan transfers designed for gravity measurements, more high northern
Titan observations, and a third horizontal ring occultation. It is generally
referred to as the high northern Titan groundtrack phase.
Extended Mission Sequence Boundries
-----------------------------------
Sequence Rev Epoch (SCET) DOY Duration
In days
-------- --- ----------------- --- --------
S42 74 2008-Jul-01 19:08 183 40
S43 80 2008-Aug-11 00:20 224 34
S44 84 2008-Sep-13 22:19 257 35
S45 89 2008-Oct-18 20:21 292 39
S46 94 2008-Nov-26 17:55 331 44
S47 100 2009-Jan-09 15:16 009 39
S48 103 2009-Feb-17 12:35 048 37
S49 106 2009-Mar-26 10:05 085 40
S50 110 2009-May-05 07:16 125 39
S51 112 2009-Jun-13 04:41 164 41
S52 115 2009-Jul-23 21:51 204 32
S53 117 2009-Aug-25 01:00 237 41
S54 119 2009-Oct-05 04:03 278 40
S55 121 2009-Nov-13 19:21 317 39
S56 123 2009-Dec-22 23:26 356 32
S57 125 2010-Jan-23 15:00 023 37
S58 127 2010-Mar-01 19:04 060 34
S59 129 2010-Apr-05 02:49 095 42
S60 131 2010-May-17 13:31 137 34
S61* 133 2010-Jun-25 11:11 176 35
S62* 135 2010-Jul-30 21:10 211 37
S63* 137 2010-Sep-06 06:33 249 35
S64** 139 2010-Oct-11 04:17 284 70
S65** 141 2010-Nov-29 TBS 333 49
S66** 143 2011-Jan-17 TBS 017 49
S67** 146 2011-Mar-07 TBS 066 49 thru 4/24 (114)
*XXM bridge sequences
**XXM transition sequences. Start times To Be Specified (TBS);
not defined at the time of this update.
Extended Mission Satellite Encounter
------------------------------------
*Targeted fly-by
Rev Name Satellite Epoch (SCET) DOY Alt in/ Speed Phase
km out km/s deg
---- ----- --------- ---------------- --- --- --- ----- ----
74 74TI Titan 2008-Jun-28 15:56 180 730742 in 7.9 107
74 74PM Prometheus 2008-Jun-30 08:13 182 61967 in 22.6 107
74 74EN Enceladus 2008-Jun-30 08:42 182 84978 in 21.1 51
74 74JA Janus 2008-Jun-30 08:55 182 33087 in 22.6 122
74 74ME Methone 2008-Jun-30 09:01 182 87770 in 22.6 93
74 74AT Atlas 2008-Jun-30 09:19 182 77022 out 24.1 118
75 75JA Janus 2008-Jul-07 08:55 189 79291 in 22.6 94
75 75PA Pandora 2008-Jul-07 09:36 189 23856 in 22.6 156
75 75ME Methone 2008-Jul-07 10:00 189 118366 out 23.4 102
76 76DA Daphnis 2008-Jul-14 10:05 196 42601 in 22.6 120
76 76PM Prometheus 2008-Jul-14 10:12 196 31422 in 22.5 130
76 76PL Pallene 2008-Jul-14 10:35 196 93050 in 22.1 85
76 76TI Titan 2008-Jul-15 21:25 196 542450 out 8.4 127
77 77PL Pallene 2008-Jul-21 11:06 203 59024 in 21.0 26
77 77AT Atlas 2008-Jul-21 11:23 203 28457 in 22.7 155
77 77DA Daphnis 2008-Jul-21 11:59 203 86127 out 24.4 118
77 77PN PAN 2008-Jul-21 12:03 203 91248 out 24.6 118
78 78PN PAN 2008-Jul-28 11:25 210 97452 in 23.3 102
78 78PM Prometheus 2008-Jul-28 12:18 210 24666 in 22.6 160
78 78EP Epimetheus 2008-Jul-28 13:01 210 106965 out 24.6 113
78* 78TI Titan 2008-Jul-31 02:13 213 1613 out 6.2 49
79 79MI Mimas 2008-Aug-04 10:27 217 122378 in 19.0 110
79 79EP Epimetheus 2008-Aug-04 12:48 217 101809 out 19.8 143
80 80ME Methone 2008-Aug-11 20:41 224 60470 in 18.4 127
80* 80EN Enceladus 2008-Aug-11 21:06 224 50 in 17.7 110
80 80MI Mimas 2008-Aug-11 21:48 224 81525 out 19.1 137
80 80DA Daphnis 2008-Aug-11 21:55 224 109997 out 20.3 149
81 81TI Titan 2008-Aug-15 20:47 228 302605 in 5.9 22
81 81PL Pallene 2008-Aug-19 06:09 232 44152 in 18.4 134
81 81PN Pan 2008-Aug-19 06:44 232 114866 out 18.4 146
82 82AT Atlas 2008-Aug-26 14:07 239 107399 in 19.9 150
83 83TI Titan 2008-Aug-31 13:12 244 603610 in 6.9 97
83 83JA Janus 2008-Sep-02 23:28 246 87029 in 19.4 156
83 83ME Methone 2008-Sep-03 00:26 247 90910 out 19.2 128
84 84EP Epimetheus 2008-Sep-10 08:51 254 91396 in 19.6 155
85 85TI Titan 2008-Sep-15 23:39 259 902767 in 8.7 99
85 85PA Pandora 2008-Sep-17 16:36 261 106659 in 19.7 143
85 85MI Mimas 2008-Sep-17 16:50 261 61670 in 18.3 139
85 85CA Calypso 2008-Sep-17 17:19 261 60479 in 17.5 45
85 85DA Daphnis 2008-Sep-17 17:55 261 108427 out 20.2 151
86 86TE Tethys 2008-Sep-25 01:24 269 110414 in 17.5 23
86 86AT Atlas 2008-Sep-25 01:41 269 105297 in 19.9 150
86 86PN Pan 2008-Sep-25 02:14 269 105237 in 20.1 157
86 86PL Pallene 2008-Sep-25 03:12 269 114652 out 19.3 118
87 87TE Tethys 2008-Oct-02 11:03 276 78632 in 17.6 70
87 87TI Titan 2008-Oct-03 23:03 277 780488 out 9.3 125
88 88TL Telesto 2008-Oct-09 18:46 283 67251 in 17.2 22
88 88JA Janus 2008-Oct-09 18:56 283 89531 in 19.4 151
88* 88EN Enceladus 2008-Oct-09 19:06 283 25 in 17.7 113
89 89PL Pallene 2008-Oct-17 02:57 291 29037 in 18.1 141
89 89EP Epimetheus 2008-Oct-17 04:22 291 118902 out 20.3 136
89 89TI Titan 2008-Oct-19 05:24 293 397750 out 7.1 125
90 90JA Janus 2008-Oct-24 09:13 298 108155 in 19.5 132
90 90PN Pan 2008-Oct-24 10:07 298 105477 in 20.1 156
90 90MI Mimas 2008-Oct-24 10:24 298 57292 in 18.3 155
91 91ME Methone 2008-Oct-31 16:02 305 116144 in 18.8 102
91 91PA Pandora 2008-Oct-31 16:30 305 111476 in 19.8 138
91 91DA Daphnis 2008-Oct-31 17:13 305 102904 in 19.9 155
91* 91EN Enceladus 2008-Oct-31 17:14 305 196 in 17.7 113
91 91AT Atlas 2008-Oct-31 18:10 305 112339 out 20.3 147
91 91EP Epimetheus 2008-Oct-31 18:35 305 118943 out 20.3 136
91* 91TI Titan 2008-Nov-03 17:35 308 1100 out 6.3 171
92 92PO Polydeuces 2008-Nov-08 21:01 313 121408 in 15.3 12
92 92TL Telesto 2008-Nov-08 21:31 313 64794 in 16.4 84
92 92EN Enceladus 2008-Nov-08 21:51 313 52801 in 16.8 128
93 93TE Tethys 2008-Nov-16 20:14 321 57060 in 15.9 41
93* 93TI Titan 2008-Nov-19 15:56 324 1022 out 6.3 28
94 94HE Helene 2008-Nov-24 08:25 329 65068 in 14.3 14
94 94TE Tethys 2008-Nov-24 08:44 329 24233 in 15.2 159
95 95EN Enceladus 2008-Dec-02 06:35 337 122550 in 15.7 115
95 95CA Calypso 2008-Dec-02 07:16 337 68176 in 15.2 93
95* 95TI Titan 2008-Dec-05 14:25 337 960 out 6.3 25
96 96CA Calypso 2008-Dec-09 18:39 344 74910 out -2.0 155
97* 97TI Titan 2008-Dec-21 12:59 356 970 out 6.3 83
100 100TI Titan 2009-Jan-14 09:26 014 704012 out 9.3 25
102 102RH Rhea 2009-Feb-02 10:43 033 97433 in 10.4 82
102* 102TI Titan 2009-Feb-07 08:50 038 960 out 6.3 136
103 103TI Titan 2009-Feb-13 18:26 044 706923 in 7.7 98
106 106TI Titan 2009-Mar-21 11:50 080 991403 in 8.0 63
106* 106TI Titan 2009-Mar-27 04:43 086 960 out 6.3 84
108* 108TI Titan 2009-Apr-04 01:47 094 4150 in 5.8 151
108 108TI Titan 2009-Apr-11 17:34 101 326591 out 6.0 67
109* 109TI Titan 2009-Apr-20 00:20 110 3600 in 5.8 149
109 109TI Titan 2009-Apr-27 04:03 117 695883 out 6.3 64
110* 110TI Titan 2009-May-05 22:54 125 3244 in 5.8 146
111* 111TI Titan 2009-May-21 21:26 141 965 in 6.0 141
112* 112TI Titan 2009-Jun-06 20:00 157 965 in 6.0 135
113* 113TI Titan 2009-Jun-22 18:32 173 955 in 6.0 128
114* 114TI Titan 2009-Jul-08 17:04 189 965 in 6.0 120
114 114DI Dione 2009-Jul-11 03:12 192 86634 out 9.2 62
115* 115TI Titan 2009-Jul-24 15:34 205 955 in 6.0 112
115 115PM Prometheus 2009-Jul-26 16:18 207 113286 out 10.4 79
115 115PA Pandora 2009-Jul-26 16:48 207 103479 out 10.1 65
115 115JA Janus 2009-Jul-26 17:06 207 94990 out 9.9 59
115 115TE Tethys 2009-Jul-26 18:14 207 68369 out 9.5 89
116* 116TI Titan 2009-Aug-09 14:03 221 970 in 6.0 104
116 116AT Atlas 2009-Aug-11 11:26 223 119005 in 14.4 117
117* 117TI Titan 2009-Aug-25 12:51 237 970 in 6.0 86
117 117PL Pallene 2009-Aug-27 11:03 239 101876 out 7.5 120
117 117TL Telesto 2009-Aug-27 13:12 239 24674 out 5.8 86
118 118PM Prometheus 2009-Sep-20 10:09 263 121198 out 2.7 74
118 118DI Dione 2009-Sep-20 16:52 263 97914 out 9.8 94
118 118TI Titan 2009-Sep-22 06:53 265 293611 out 4.8 113
119* 119TI Titan 2009-Oct-12 08:36 285 1300 in 6.0 99
119 119RH Rhea 2009-Oct-13 16:55 286 40384 in 9.0 82
119 119ME Methone 2009-Oct-14 03:18 287 85989 in 11.8 39
119 119AT Atlas 2009-Oct-14 04:19 287 70794 in 2.9 114
119 119CA Calypso 2009-Oct-14 04:33 287 100778 in 7.7 107
119 119MI Mimas 2009-Oct-14 06:32 287 44193 out 7.9 102
119 119TE Tethys 2009-Oct-14 10:10 287 85262 out 11.9 76
120 120TI Titan 2009-Nov-01 23:57 305 978751 in 9.9 73
120 120PL Pallene 2009-Nov-02 02:07 306 93935 in 12.6 46
120 120EP Epimetheus 2009-Nov-02 05:26 306 105166 out 8.0 6
120 120CA Calypso 2009-Nov-02 06:55 306 86768 out 6.9 117
120* 120EN Enceladus 2009-Nov-02 07:41 306 90 out 7.7 90
121 121HE Helene 2009-Nov-20 22:04 324 82610 in 6.6 105
121* 121EN Enceladus 2009-Nov-21 02:09 325 1602 in 7.8 87
121 121PA Pandora 2009-Nov-21 04:45 325 59374 in 3.0 103
121 121TI Titan 2009-Nov-21 08:30 325 965087 out 11.1 138
121 121CA Calypso 2009-Nov-21 10:19 325 36984 out 10.0 78
121 121RH Rhea 2009-Nov-21 17:35 325 24417 out 8.7 58
122 122HE Helene 2009-Dec-09 22:28 343 31701 in 9.6 73
122 122PL Pallene 2009-Dec-10 03:33 344 111152 in 13.7 47
122* 122TI Titan 2009-Dec-12 01:03 346 4850 out 5.7 124
123 123TE Tethys 2009-Dec-26 00:35 360 52923 in 11.8 77
123 123PM Prometheus 2009-Dec-26 05:01 360 56433 in 10.5 36
123* 123TI Titan 2009-Dec-28 00:16 362 955 out 5.9 86
124 124PA Pandora 2010-Jan-11 02:08 011 73215 in 7.1 141
124 124ME Methone 2010-Jan-11 02:26 011 27180 in 8.0 145
124 124EN Enceladus 2010-Jan-11 06:47 011 105775 out 11.4 98
124 124CA Calypso 2010-Jan-11 08:17 011 112930 out 8.0 102
124* 124TI Titan 2010-Jan-12 23:10 012 1072 out 5.9 95
125 125TL Telesto 2010-Jan-27 00:29 027 97030 in 7.2 91
125 125ME Methone 2010-Jan-27 01:39 027 72090 in 14.0 60
125 125PN Pan 2010-Jan-27 04:31 027 97922 out 14.8 123
125 125PM Prometheus 2010-Jan-27 04:36 027 32501 out 7.2 112
125 125DI Dione 2010-Jan-27 11:47 027 45083 out 8.7 106
125* 125TI Titan 2010-Jan-28 22:28 028 7490 out 5.7 69
126 126CA Calypso 2010-Feb-13 11:44 044 21216 in 10.1 72
126 126EP Epimetheus 2010-Feb-13 16:16 044 93127 in 12.4 30
126 126JA Janus 2010-Feb-13 16:22 044 114980 in 14.4 29
126 126MI Mimas 2010-Feb-13 17:22 044 9526 out 5.8 99
126 126TE Tethys 2010-Feb-13 18:15 044 111962 out 8.2 114
126 126TI Titan 2010-Feb-14 22:26 045 650578 out 8.8 32
127* 127RH Rhea 2010-Mar-02 17:40 061 100 in 8.6 87
127 127PN Pan 2010-Mar-03 04:37 062 103805 in 6.0 149
127 127CA Calypso 2010-Mar-03 11:03 062 91805 out 12.8 77
127* 127HE Helene 2010-Mar-03 13:40 062 1822 out 9.1 106
128 128TI Titan 2010-Mar-19 14:40 078 648389 in 8.9 119
128 128TL Telesto 2010-Mar-20 16:21 079 89557 in 12.7 72
128 128AT Atlas 2010-Mar-20 20:52 079 106382 in 10.4 137
128 128PM Prometheus 2010-Mar-20 21:14 079 43759 in 4.2 107
128 128DA Daphnis 2010-Mar-20 21:45 079 60921 out 5.3 25
128 128ME Methone 2010-Mar-20 23:34 079 56403 out 11.2 99
128 128PL Pallene 2010-Mar-21 00:07 080 74781 out 12.7 94
128 128PO Polydeuces 2010-Mar-21 04:51 080 33102 out 10.3 70
129* 129TI Titan 2010-Apr-05 15:50 095 7461 in 5.7 73
129* 129DI Dione 2010-Apr-07 05:16 097 503 in 8.4 79
129 129CA Calypso 2010-Apr-07 08:00 097 97923 in 11.7 69
129 129EP Epimetheus 2010-Apr-07 12:45 097 61716 in 2.4 89
129 129JA Janus 2010-Apr-07 13:43 097 74605 out 2.8 40
129 129MI Mimas 2010-Apr-07 13:46 097 97420 out 10.3 124
129 129TE Tethys 2010-Apr-07 14:58 097 70783 out 6.4 103
130 130PM Prometheus 2010-Apr-27 20:38 117 84544 in 1.6 116
130 130TL Telesto 2010-Apr-27 20:45 117 79578 in 6.7 97
130 130TI Titan 2010-Apr-27 21:09 117 989097 in 12.5 94
130 130DA Daphnis 2010-Apr-27 22:41 117 86342 out 1.4 47
130 130PA Pandora 2010-Apr-27 23:05 117 91594 out 1.8 34
130 130PL Pallene 2010-Apr-27 23:46 117 71216 out 9.7 112
130 130PN Pan 2010-Apr-27 23:52 117 113808 out .5 24
130* 130EN Enceladus 2010-Apr-28 00:10 118 99 out 6.5 93
131* 131EN Enceladus 2010-May-18 06:04 138 197 in 6.5 108
131 131ME Methone 2010-May-18 08:19 138 18468 in 4.3 75
131* 131TI Titan 2010-May-20 03:24 140 1400 out 5.9 112
132 132HE Helene 2010-Jun-03 00:38 154 114498 in 11.8 85
132 132CA Calypso 2010-Jun-03 06:10 154 119761 in 8.9 80
132 132PA Pandora 2010-Jun-03 07:15 154 97613 in 14.1 44
132 132TE Tethys 2010-Jun-03 12:56 154 52611 out 9.6 99
132 132RH Rhea 2010-Jun-03 20:31 154 69386 out 8.0 102
132* 132TI Titan 2010-Jun-05 02:26 156 2044 out 5.8 87
133 133RH Rhea 2010-Jun-18 19:49 169 121264 in 10.7 109
133 133PN Pan 2010-Jun-19 07:08 170 28974 out 4.9 113
133 133PO Polydeuces 2010-Jun-19 14:07 170 97267 out 12.4 79
133 133TI Titan 2010-Jun-21 01:27 172 955 out 5.9 82
134 134CA Calypso 2010-Jul-05 00:38 186 112762 in 12.6 70
134 134EN Enceladus 2010-Jul-05 02:06 186 55963 in 11.2 58
134 134DA Daphnis 2010-Jul-05 05:02 186 69384 in 9.0 50
134* 134TI Titan 2010-Jul-07 00:26 188 1004 out 5.9 82
135 135PM Prometheus 2010-Jul-25 03:30 206 70112 out 2.2 69
135 135AT Atlas 2010-Jul-25 04:32 206 89635 out 2.0 37
136 136TI Titan 2010-Aug-11 13:36 223 417010 in 4.0 80
136 136DI Dione 2010-Aug-13 17:43 225 108621 in 11.3 84
136 136CA Calypso 2010-Aug-13 20:29 225 22857 in 7.4 99
136* 136EN Enceladus 2010-Aug-13 22:29 225 2651 in 6.9 85
136 136EP Epimetheus 2010-Aug-13 23:22 225 101275 in 3.8 149
136 136AT Atlas 2010-Aug-14 00:33 226 73634 in 2.1 102
136 136PA Pandora 2010-Aug-14 01:08 226 67383 out 2.3 78
136 136DA Daphnis 2010-Aug-14 01:25 226 74092 out 2.1 68
136 136JA Janus 2010-Aug-14 02:01 226 79900 out 3.4 34
136 136PN Pan 2010-Aug-14 02:05 226 86649 out 1.8 47
136 136TE Tethys 2010-Aug-14 06:02 226 36965 out 9.2 90
137 137PO Polydeuces 2010-Sep-02 18:13 245 60519 in 7.2 95
137 137TL Telesto 2010-Sep-02 20:31 245 78878 in 11.1 73
137 137PM Prometheus 2010-Sep-02 22:52 245 119913 in 1.6 152
137 137TI Titan 2010-Sep-03 02:15 246 985950 out 12.6 103
137 137EP Epimetheus 2010-Sep-03 03:05 246 103009 out 4.0 18
137 137DI Dione 2010-Sep-03 09:04 246 33089 out 9.0 83
138 138EN Enceladus 2010-Sep-23 03:14 266 116859 out 12.9 104
138 138CA Calypso 2010-Sep-23 05:03 266 30357 out 8.5 87
138 138PO Polydeuces 2010-Sep-23 07:32 266 103504 out 11.3 82
138* 138TI Titan 2010-Sep-24 18:45 267 8124 out 5.7 60
139 139TI Titan 2010-Oct-14 17:18 287 177672 in 4.8 80
139 139PO Polydeuces 2010-Oct-16 11:03 289 103515 in 10.5 73
139 139MI Mimas 2010-Oct-16 17:30 289 77824 in 2.6 116
139 139PL Pallene 2010-Oct-16 18:33 289 39943 out 3.8 100
139 139ME Methone 2010-Oct-16 18:48 289 89892 out 5.0 28
139 139TL Telesto 2010-Oct-16 19:06 289 47845 out 5.5 98
139 139GR G_Arc 2010-Oct-16 19:09 289 87310 out 1.9 51
139 139DI Dione 2010-Oct-17 01:30 290 23296 out 7.1 89
139 139RH Rhea 2010-Oct-17 07:07 290 31095 out 7.2 99
140 140DI Dione 2010-Nov-09 11:05 313 93182 in 10.0 74
140 140EN Enceladus 2010-Nov-09 16:36 313 37781 in 6.1 51
140* 140TI Titan 2010-Nov-11 13:45 315 7921 out 5.6 121
141 141HY Hyperion 2010-Nov-28 03:31 332 71598 in 4.9 73
141 141TI Titan 2010-Nov-29 06:28 333 925255 in 10.5 130
141 141AT Atlas 2010-Nov-30 07:16 334 115433 in .7 145
141 141JA Janus 2010-Nov-30 11:11 334 94007 out 2.5 30
141 141EN Enceladus 2010-Nov-30 11:55 334 49 out 6.3 97
142 142TI Titan 2010-Dec-16 19:58 350 849313 in 3.6 91
142 142TI Titan 2010-Dec-20 12:21 354 894223 in 6.3 46
142 142DI Dione 2010-Dec-20 16:57 354 102068 in 5.9 87
142 142PN Pan 2010-Dec-20 20:35 354 116360 in .3 142
142 142PA Pandora 2010-Dec-20 20:41 354 109916 in 1.1 144
142 142DA Daphnis 2010-Dec-20 23:34 254 83742 out 1.3 62
142* 142EN Enceladus 2010-Dec-21 01:12 355 47 out 6.3 102
143 143PA Pandora 2011-Jan-10 14:41 010 96658 in 1.5 135
143 143ME Methone 2011-Jan-10 17:28 010 88471 out 9.7 127
143 143TI Titan 2011-Jan-11 03:19 011 839835 out 5.9 140
143* 143RH Rhea 2011-Jan-11 04:57 011 200 out 8.1 101
143 143TI Titan 2011-Jan-14 09:29 014 774014 out 3.6 96
144 144EP Epimetheus 2011-Jan-31 02:15 031 68194 in 2.6 116
144 144CA Calypso 2011-Jan-31 03:49 031 78430 out 6.7 95
144 144PM Prometheus 2011-Jan-31 04:46 031 104606 out 1.2 33
144 144EN Enceladus 2011-Jan-31 05:53 031 59635 out 9.6 110
144 144HE Helene 2011-Jan-31 10:18 031 28880 out 7.5 92
145* 145TI Titan 2011-Feb-18 16:04 049 3639 in 5.8 62
145 145EN Enceladus 2011-Feb-20 14:02 051 65902 out 4.2 133
145 145PL Pallene 2011-Feb-20 14:47 051 92857 out 2.8 55
145 145TE Tethys 2011-Feb-20 17:10 051 45142 out 6.6 123
146 146TL Telesto 2011-Mar-20 12:30 079 10422 out 4.4 83
147 147GR G_Arc 2011-Apr-17 09:07 107 118988 in .6 114
147 147HE Helene 2011-Apr-17 14:07 107 66896 out 5.2 81
147* 147TI Titan 2011-Apr-19 05:10 109 9995 out 5.6 101
EXTENDED-EXTENDED MISSION 2010-09-30 to 2017-09-15
2010-273 to 2017-258
-------------------------
The proposed XXM is a seven-year extended mission which will continue
exploring the features of the Saturnian system such as the rings, the
magnetosphere, Titan, and the icy satellites, especially Enceladus. The
seven year extension will also allow for the observation of the Northern
summer solstice at Saturn.
The proposed tour contains five phases; two contain equatorial orbits
while the other phases are characterized by inclined orbits. The proposed
XXM features 54 Titan flybys, 23 close icy flybys (which include 11
Enceladus flybys), and 156 orbits of Saturn.
The first inclined phase, In-0, begins where the EM ended. The inclination
is decreased over four months such that the subsequent transfer is
equatorial. The second phase of the proposed SM takes place over 18 months
and is characterized by equatorial orbits. During this phase, high northern
Saturn occultations and Saturn observations free of ring obstruction will
be completed. The first seven targeted Enceladus flybys occur here, as well
as close flybys of Rhea, Helene, Dione (twice), Tethys and Methone. Several
of the Enceladus flybys will include plume passages.
The third phase is dominated by highly inclined orbits. These orbits will
enable ring observations, magnetotail crossings, and Saturn high-latitude
occultations. Titan flyby geometries allow for many low altitude,
non-equatorial groundtracks.
The fourth phase is eight months long and is comprised of equatorial orbits.
The final three targeted Enceladus encounters and two close Dione flybys
will occur here. This phase is important for setting up the orbit geometry
for the proximal orbits in the final tour phase. The final phase of the
tour contains a series of Titan flybys which allow for numerous Titan polar
occultations, as well as low altitude groundtracks. This phase also
includes long duration Saturn occultations to enable Saturn eclipse imaging.
The F-ring orbits begin on 29-Nov-2016.
The periapse radii of these 20 orbits is ~2.5 RS which puts the spacecraft
between the F-ring and the G-ring. These orbits will allow for quality,
close-up observations of the rings and other features of the Saturnian
system at low phase.
Extended-Extened Mission Sequence Boundries
-------------------------------------------
Sequence Rev Epoch (SCET) DOY Duration
In days
-------- --- ----------------- --- --------
To Be Specified; not defined at the time of this update
Extended-Extended Mission Satellite Encounter
---------------------------------------------
Rev Name Satellite Epoch (SCET) DOY Alt in/ Speed Phase
km out km/s deg
---- ----- --------- ---------------- --- --- --- ----- ----
To Be Specified; not defined at the time of this update
END OF MISSION 2017-09-15
2017-258
--------------
The Cassini navigation team has discovered that it is possible to move the
spacecraft orbit's inner ring-plane crossing all the way over Saturn's
entire main ring system, from just beyond the F ring, to the cleared gap
between Saturn's upper atmosphere and inner portion of the main rings, using
one single Titan flyby. So far, it has been impossible to get very close to
Saturn itself due to the presence of the main rings out to over 140,000 km
from the center of Saturn. During SOI the spacecraft passed 18,000 km from
the cloud tops, and that is the closest the project ever expected to get to
the planet and rings, enabled by the hyperbolic approach trajectory. It was
thought that there was no feasible way to construct an orbit with reasonable
period that gets any closer to Saturn and yet does not pass through the main
rings - the implementation of which would undoubtedly destroy the
spacecraft. No safe gaps in the main ring system exist that could be
employed as intermediate steps.
This proximal orbit geometry is implemented by raising the orbit inclination
to a moderately high level (~63 degrees) and placing the inner ring-plane
crossing barely but safely outside the main rings. The other ring-plane
crossing is located at Titan, as usual, since Cassini must continually
encounter Titan to employ its significant gravity assist resources. Then,
with one flyby, the orbit is altered to move the ring-plane crossing to
between 2,000 and 5,000 above the 'cloud tops' of Saturn (1 bar level). The
environment is known well enough for the project to conclude with sufficient
confidence that the risk of debris impact or atmospheric tumbling is
acceptably small. Furthermore, the radiation environment is not
significantly different from that experienced during SOI.
The proposed end phase includes 22 orbits in this region, called proximal
orbits. This Juno-like mission phase offers significant unique science
opportunities for Cassini, including gravity mapping measurements, high
resolution ring observations, and in-situ measurements of Saturn's
atmosphere.
Final disposal of the spacecraft will take place within Saturn's atmosphere
on 15 September 2017. This entire trajectory, starting after the last
targeted proximal-injecting Titan flyby, is entirely ballistic, requiring
no further maneuvers. In other words, the end of mission is assured
regardless of the spacecraft condition. It is anticipated that this disposal
strategy will be acceptable for Planetary Protection.
END OF MISSION
--------------