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Going Out in a Blaze of Glory: Cassini Science

Highlights and Grand Finale

Trina L. Raywith thanks to

Earl Maize and Linda Spilker, and Erick Sturm1

Cassini Orbiter & Huygens Probe

Cassini Spacecraft Specs

• Height: 6.8 m (22 ft)

• Diameter: 4 m (13 ft)

• Mass: 2125 kg (2.8 tons)

(fueled+probe): 5574 kg (6 tons)

• Power: 875 Watts at Launch

670 Watts currently

• .5 GB recorder

• Huygens Probe:

320 kg (~700 lbs)

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Cassini Instruments:

Optical Remote Sensing (ORS)

CIRS: Composite Infrared Spectrometer

ISS: Imaging Science Subsystem

UVIS: Ultraviolet Imaging Spectrograph

VIMS: Visual and Infrared mapping

Spectrometer

Microwave Remote Sensing

RADAR: Cassini Radar

RSS: Radio Science Subsystem

Magnetospheric and Plasma Science

(MAPS)

CAPS: Cassini Plasma Spectrometer

CDA: Cosmic Dust Analyzer

INMS: Ion and Neutral Mass Spectrometer

MAG: Magnetometer

MIMI: Magnetospheric Imaging Instrument

RPWS: Radio and Plasma Wave Science

The 12 Orbiter Instruments

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Launched on October 15, 1997 from KSC

7 year cruise on VVEJGA trajectory

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Cassini-Huygens Mission Overview

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Protecting Saturn’s Ocean Worlds

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Solstice Mission TrajectoryRing-Grazing orbitsGrand Finale orbitsImpact orbit

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Challenges

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Mind the Gap

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Mind the Gap

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Mind the Gap

Ring-planeCrossings

MinimumAltitudes

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Mind the Gap

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Dust Hazard Plan

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Saturn Atmosphere

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CassiniMission Planning

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Tumble Boundary forReaction Wheels

D Ring

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Tumble Boundary for Thrusters

Spacecraft Capture Boundary

1-Bar Atmospheric Pressure

CassiniMission Planning Atmosphere Protection

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Spacecraft Capture Boundary

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Grand Finale ObjectivesBringing Cassini closer to Saturn

than ever before

Planetary Protection

• Spacecraft disposal

Unique Science

• Saturn internal structure• Magnetic & gravity high-order

moment measurements

• Ring mass• Address age of main rings

• In-situ measurements• Ionosphere, inner radiation belts,

auroral region, and D ring particles

• High resolution observations• Rings, poles/aurora, atmosphere

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Grand Finale Objectives36 passes needed, we have 22

Unique Science

• Saturn internal structure• Magnetic & gravity high-order

moment measurements

• Ring mass• Address age of main rings

• In-situ measurements• Ionosphere, inner radiation belts,

auroral region, and D ring particles

• High resolution observations• Rings, poles/aurora, atmosphere

RSS – 6 flybysAntenna to Earth

MAG – 4 flybysRolling about 2 axes

CDA - 8

CIRS – 3 to 4 (at +1hour)

INMS - 8

ISS – 43 Cameras to Saturn

1 Cameras to Ring

RADAR 3 1 Z to Saturn3 Z to Ring

UVIS – 21 Cameras to Saturn (slewing)1 Cameras to Rings (slewing)

VIMS – 5 (cold at +1 hour)

MIMI & RPWS – all (but no pointing constraint)

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Grand Finale Sharing

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Highlights

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Pan

Daphnis

Atlas

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150 m/pixel (500 feet/pixel)

Pan

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168 m/pixel 168 m/pixel (551 feet/pixel)

Daphnis

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Atlas Shoulders Weight of Rings

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Cassini Makes Historic Passage

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Grand Finale Sharing

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Saturn Radio Plasma Waves

What We Expected

What We Saw

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Saturn Noodle

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April 26, 2017 June 29, 2017

Saturn Noodle

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Cassini Grand Finale

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Cassini Grand Finale

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RSS Gravity + Occultation

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Cassini Grand Finale

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Saturn’s Rings at High Resolution

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Saturn’s Rings at High Resolution

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Cassini Grand Finale

It’s hard…not everything goes perfectly49

Puzzles and more puzzles

So far: • the magnetic field is surprisingly well-aligned with the

planet's rotation axis. The tilt is much smaller than 0.06 degrees -- which is the lower limit the spacecraft's magnetometer data placed on the value prior to the start of the Grand Finale. "The tilt seems to be much smaller than we had previously estimated and quite challenging to explain," said Michele Dougherty, Cassini magnetometer investigation lead at Imperial College, London.

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Cassini Grand Finale

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Saturn Southern Aurora

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Nov 29, 2010

July 20, 2017

Cassini Grand Finale

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Project Manager Significant Event

Report for 8/09/17 - 8/15/17

• On August 13th, 2017 Cassini successfully completed its 18th

ringplane passage between Saturn and its innermost rings,

out of a total of 22. This passage was the first of these

crossings where the spacecraft briefly passed through the

upper reaches of Saturn’s atmosphere

• The Ion and Neutral Mass Spectrometer (INMS) was prime

during the passage, and it performed the first-ever direct

sampling of Saturn’s atmosphere. As expected, the spacecraft

had to utilize its thrusters to offset the torque imparted by

atmospheric drag. The torque was higher than predicted,

which was good news about atmospheric density for INMS,

but it remained well within the attitude control system’s control

authority.

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Cassini Grand Finale

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The Last Day

Peggy

Enceladus setting

behind SaturnPropellers

Saturn and Rings

Titan

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Saturn.jpl.nasa.gov

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Questions?

http://saturn.jpl.nasa.gov62