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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Ring-Plane Crossings
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Proximal Corridor
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Ring-Plane Crossings
D-Ring DetectionBoundary
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Ring-Plane Crossings
Shielded Crossings
D-Ring DetectionBoundary
Minimum Altitudes
Dust Hazard Plan
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Saturn Atmosphere
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1.0E-13
1.0E-11
1.0E-09
1.0E-07
1.0E-05
1.0E-03
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CassiniMission Planning
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D-Ring DetectionBoundary
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D Ring
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D Ring
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D Ring
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D Ring
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Minimum Altitudes
Tumble Boundary forReaction Wheels
D Ring
Proximal Corridor
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Tumble Boundary for Thrusters
Spacecraft Capture Boundary
1-Bar Atmospheric Pressure
CassiniMission Planning Atmosphere Protection
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Thruster Controlled
Tumble Boundary forReaction Wheels
D Ring
Tumble Boundary for Thrusters
Spacecraft Capture Boundary
1-Bar Atmospheric Pressure
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
65 m/pixel (250 feet/pixel)31
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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