Cassini s Grand Finale Science Highlights & End of Mission Scott G. Edgington and Linda J. Spilker Jet Propulsion Laboratory/California Institute of Technology September 6, 2017
Cassini-Huygens Mission Overview 2
Protecting Saturn s Ocean Worlds
Solstice Mission Trajectory Ring-Grazing orbits Grand Finale orbits Impact orbit 4
Key Characteristics of Final Orbits 42 short-period orbits Nov. 2016 to Sept. 2017 20 F ring orbits Periapses just outside Saturn s F ring Sets up Cassini for final jump to orbits inside D ring 22 Grand Finale orbits Periapses in 2,400 km clear zone
Titan Clouds Reappear
Saturn s Rings in High-Def Mon, Aug 14, 2017 Cassini Grand Finale - Div. 39 Noontime Seminar 7
Probing Saturn s Interior Gravity will es;mate: size of rocky core depth of winds mass distribu;on
Probing Saturn s Interior Magne;c field measurements will determine: rota;on rate depth of magne;c dynamo region
Ring Mass: Constrain age of rings 74,500 km 92,000 km 117,580 km 122,200 km 136,780 km C-Ring B-Ring GM= 1.9 km 3 /s 2 (Voyager) Cassini Division A-Ring Current uncertainty in ring mass is 100% of nominal value 6 gravity passes to measure total ring mass will reduce uncertainty to about 5% Less massive: young rings; more massive: old rings 10
First In-Situ Measurements of Exosphere and Innermost Radiation Belts Strength of innermost radiation belt Plasma composition Saturn s auroral magnetosphere 11
Final Orbits Science: Unique Observations First ever direct measurements of ring par;cle composi;on Highest resolu;on main ring observa;ons Radio occulta;on, imaging First ac;ve Radar Highest resolu;on Saturn polar observa;ons and aurora
Flying Through the Gap 22 Times
Proximal Corridor 64500 Distance from the Center of Saturn (km) 64000 63500 63000 62500 62000 61500 61000 60500 Ring-Plane Crossings Minimum Al;tudes 60000
Dust Hazard Plan Distance from the Center of Saturn (km) 64500 64000 63500 63000 62500 62000 61500 61000 60500 Ring-Plane Crossings Shielded Crossings D-Ring Detec;on Boundary Minimum Al;tudes 60000
What We Expected Saturn Radio Plasma Waves What We Saw Where are the predicted large ring par/cles?
Soaring Over Saturn s North
The First Grand Finale Crossing
Saturn Noodle
Saturn Noodle April 26, 2017 June 29, 2017
Saturn Southern Aurora Nov 29, 2010 July 20, 2017
C Ring Plateau Structure Highest Resolu;on Image AWer Processing Mon, Aug 14, 2017 Cassini Grand Finale - Div. 39 Noontime Seminar 22
Rings Inside-Out A few orbits ago, in a Ring System Not-Too-Far Away.
A Cassini Family Portrait Jupiter Pluto Uranus Mon, Aug 14, 2017 Neptune Earth and Moon
Magnetic Field Observations Tilt of Magnetic field < 0.06º
Probing Saturn s Interior & Ring Mass Early analysis of gravity data so far shows discrepancies compared with parts of leading models of Saturn's interior.
Cassini Grand Finale
Cassini s Last Days Saturn and Rings Titan Peggy Enceladus setting behind Saturn Propellers
Skimming the Atmosphere First Passage on August 13, 2017 Cassini Grand Finale - Div. 39 Noontime Seminar
Final Hour with 10 -Lat Ticks Mon, Aug 14, 2017 Cassini Grand Finale - Div. 39 30
Final 90 Seconds with 10-sec Ticks An;cipated Measurements of: Exosphere/Thermosphere (H 2, HD, He, CH 4, ) Temperature vs. Pressure Ionosphere (e -, H +, OH -, ) Ring rain Magne;c Field Plasma Waves Mon, Aug 14, 2017 Cassini Grand Finale - Div. 39 31
Grand Finale Movie
Questions?
Backup 34
Last View of the Earth
Soaring Over Saturn s North
The View from the Gap 7:50 7:56 7:58 8:11 8:27 9:00
Opening Pandora s Box
From Cassini s Vista: A Pan-tastic View
Atlas Shoulders the Weight of the Rings
Saturn s Rings at High Resolution
November 30, 2016 F-ring Orbits Begin 20 orbits 3 maneuvers Grand Finale Timeline April 22, 2017 Last Targeted Titan Flyby Produces Grand Finale trajectory April 23, 2017 Grand Finale Begins 22½ orbits 9 non-targeted Titan flybys April 26, 2017 First dive through gap September 11, 2017 Last Non-targeted Titan Flyby Puts Cassini on impact trajectory September 15, 2017 Saturn Impact