KECK INSTITUTE FOR SPACE STUDIES

     

Tidal Heating – Lessons from Io and the Jovian System

October 15 - 19, 2018
California Institute of Technology - Pasadena, CA 91125

Final Report

Workshop Overview:

The evolution of planets and satellites and their potential habitability are central questions of planetary science. Recent discoveries from spacecraft missions and telescopic programs have illuminated the central role that tidal heating plays in the evolution of worlds across our solar system and beyond. This fundamental process drives the orbital evolution of planetary-satellite systems as a whole, and shapes the surface environments and geological activity of satellites, impacting the habitability of ocean worlds (Europa, Enceladus, Titan, Ganymede, etc.). However, despite its broad ranging importance, there remain fundamental gaps in our understanding of tidal heating. For example: Where and how is tidal heat actually dissipated? How do we link laboratory experiments of rheology to planetary-scale observations of deformation or heat flow? How are subsurface oceans created and maintained?

While there are well-tested tools in place to study a variety of individual planetary processes, there is no established path forward for unraveling the interconnected roles of tidal heating and orbital evolution. Such investigations will require innovative approaches and new technologies that can pin downthe orbital evolution and deformation of these worlds, integrating laboratory work, spacecraft and ground-based observations, and numerical models. Our study will bring together some of the brightest minds in planetary science, mission design, and instrumentation to generate new, original ideas for revolutionizing our understanding of tidal heating.

Our central objective is to integrate the numerous recent advances across the relevant fields, including recent laboratory studies, new telescopic/spacecraft data, and new instrumentation under development, in order to construct a coherent path forward for establishing a definitive framework for understanding tidal heating and its influence on the evolution of planetary systems. The combination of recent scientific advances as well as the forthcoming Europa Clipper and JUICE missions, the formation of the NASA Ocean Worlds program, and current/future New Frontiers-class missions to tidally heated worlds (Io, Enceladus, Titan) make it clear that now is a critical time for integrating what we know, identifying what we do not know, and creating a clear roadmap for the future science investigations and technologies that will be needed to optimize missions in the coming decades.

Amongst the myriad tidally heated worlds in our solar system, the effects of tidal heating are most prominent within the Laplace resonance between Jupiter’s moons Io, Europa, and Ganymede. Io is the most tidally deformed and heated world in the solar system—as evidenced by the hundreds of continually erupting volcanoes across its surface, and is thus the ideal target for investigating these questions. Furthermore, while several missions are planned to explore the Jovian system in the coming decades (e.g. Europa Clipper and JUICE), our understanding of orbital dynamics and tidal heating in the system will be limited by the lack of measurements of Io. Our study will therefore emphasize the Jovian system, and Io in particular, as the best laboratory for understanding the fundamental processes of tidal heating.

Our study will be framed around three fundamental science questions:

  1. How do solid/liquid planetary bodies and planetary materials respond and deform in response to periodic tidal forcing?
  2. How do tides influence global heat flow and its variations (spatial and temporal), and how does this heat translate into specific geologic processes?
  3. How do the spins and orbits of planetary satellites respond to tides over long timescales, and how does that couple with the thermal evolution?

These questions will serve as the cornerstone for discussion in our study. We will address each question in a three-pronged approach. First, we will review and integrate recent scientific advances and the relevant new or in-development technology and instrumentation. Second, we will identify the key gaps in our current framework for understanding tides and tidal heating. Lastly, we will identify the specific requirements for bridging these gaps, including: the measurements to be acquired, the instrument technologies to be developed or matured, and the new theoretical modeling capabilities and/or data techniques to be developed. The resulting final report will represent a roadmap for future understanding of tidal heating.


Monday, October 15, 2018
Salvatori Seminar Room, South Mudd Building (3rd floor) - Caltech

Short Course:
Tidal Heating on Solar System Worlds
Introductory Lectures - Open to all interested students, researchers and faculty

Time
Event
Speaker
8:15 - 8:45 Coffee and Refreshments
8:45 - 9:00 Logistics / Introduction Michele Judd and Katherine de Kleer
9:00 ‐ 9:45 Geophysics and Interior Processes of Rocky and Icy Bodies
(5.4 MB .pdf)
Francis Nimmo
9:45 ‐ 10:30 Geological Activity on Tidally‐Heated Solar System Worlds, with an Emphasis on Io
(38 MB .pdf)
Julie Rathbun
10:30 ‐ 11:00 Break
11:00 ‐ 11:45 Planetary Materials and their Response to Tidal Deformation
(14 MB .pdf)
Christine McCarthy
11:45 ‐ 12:30 Linking Tidal, Rotational, and Orbital Evolution
(19.2 MB .pdf)
Jim Fuller
12:30 ‐ 1:30 Short Course Ends: Informal Lunch is provided outside Salvatori Seminar Room

Invitation-Only Workshop Begins:
Keck Center - Think Tank, Room 155

1:30 - 1:45 Walk to Keck Center, pick up badge and welcome packet, find seat in the Think Tank
1:45 - 2:30 Workshop Logistics and Introduction to KISS Michele Judd
2:30 - 3:00 Participant Introductions All
3:00 - 3:30 Study Vision and Goals for this Workshop
(6 MB .pdf)
Alfred McEwen, Ryan Park, and Katherine de Kleer
3:30 - 4:00 Break
4:00 - 5:00 Finalize Study Vision and Workshop Goals via Plenary Discussion and Solicitation of Lightning Talks Ryan Park, Katherine de Kleer, and Alfred McEwen
5:00 - 5:30 Current and Future Spacecraft Missions to Tidally‐Heated Worlds
(48.5 MB .pdf)
Karen Kirby
5:30 - 6:00 Pack up and walk to the Athenaeum All
6:00 Dinner at the Athenaeum

Tuesday, October 16, 2018
Keck Center - Think Tank, Room 155

Time
Event
Speaker
8:00 ‐ 8:30 Institute Opens - FREE THINK TIME
8:30 ‐ 9:00 Coffee and Refreshments at Keck Center
9:00 - 9:15 Logistics and Team Lead Goals for the Day Michele Judd
Team Leads
9:15 - 9:45

Astrometry and Tidal Migration
(13.12 MB .pdf)

Jim Fuller and Valerey Lainey
9:45 - 10:15 Thermal Emission on Io and How this Links to Volcanic Advection
(5 MB .pdf)
Ashley Davies
10:15 - 10:45

Lightning Talks (2):
1) Electrical Properties of Partial Melts
and Application to Planetary Interiors - Anne Pommier
(22.8 MB .pdf)

2) Is Io Impossible (petrologically) - Laszlo Kestay
(3.44 MB .pdf)

Anne Pommier

Laszlo Kestay

10:45 - 11:15 Break
11:15 ‐ 11:25 Selection of initial Breakout Groups All
11:25 ‐ 12:30 Breakout Groups Meet Groups
12:30 ‐ 2:00 Group Picture and Lunch at the Athenaeum
2:00 - 2:45 Report outs from breakout groups (15 mins each) Group leads
2:45 ‐ 3:15

Lightning Talks (2)

TBD by participants

3:15 - 3:30 Selection of Breakout Groups and Topics All
3:30 ‐ 4:00 Break
4:00 - 5:30 Breakout Groups Meet Groups
5:30 - 7:30 POSTER SESSION and Informal food truck dinner at the Keck Center
(dinner starts at 6:30 pm)

Wednesday, October 17, 2018

Keck Center - Think Tank, Room 155

Time
Event
Speaker
8:00 ‐ 8:30 Institute Opens - FREE THINK TIME
8:30 - 9:00 Coffee and Refreshments at Keck Center
9:00 - 9:15 Logistics and Team Lead Goals for the Day Michele Judd and Team Leads
9:15 - 9:45

Report Outs from Breakout Groups (10 mins each)

Group Leads
9:45 ‐ 10:15 Tidal Heating of Ocean Worlds
(6.5 MB .pdf)
Isamu Matsuyama
10:15 ‐ 10:45 Tidal Heating in Rocky Worlds
(1.3 MB .pdf)
David Stevenson
10:45 - 11:15 Break
11:15 ‐ 12:00

Lightning talks (3):

1) How do we study a planetary interior with
gravity and topography? - Anton Ermakov
(4.28 MB .pdf)

Anton Ermakov

12:00 ‐ 12:30 Plenary Discussion, Selection of Breakout Groups and Topics All
12:30 ‐ 2:00 Lunch at the Athenaeum
2:00 - 3:30 Breakout Groups Meet All
3:30 ‐ 4:00 Break
4:00 - 4:45 Report outs from breakout groups (15 mins each) Group Leads
4:45 - 5:30 Plenary Discussion on Participant Wants and Needs
Selection of Next Day's Breakout Groups
All
5:30 Workshop Day #3 Ends All
6:00 OPTIONAL: No-Host Dinner in Pasadena

Thursday, October 18, 2018

Keck Center - Think Tank, Room 155

Time
Event
Speaker
8:00 - 8:30 Institute Opens - FREE THINK TIME
8:30 - 9:00 Coffee and Refreshments at Keck Center
9:00 - 9:15 Logistics and Team Lead Goals for the Day Michele Judd and Team Leads
9:15 - 9:45

Magnetic Induction Study of Interiors
(7 MB .pdf)

Krishan Khurana
9:45 ‐ 10:15 Seismology of Tidally Active Worlds
(23.07 MB .pdf)
Mark Panning
10:15 - 10:45

Lightning talks (2):

1)A few notes on InSAR - Laszlo Kestay
(1.33 MB .pdf)

2) Plasma interaction at Io and Europa - Camilla Harris
(5.6 MB .pdf)

Laszlo Kestay

Camilla Harris

10:45 - 11:15 Break
11:15 - 12:30 Breakout Groups Meet All
12:30 ‐ 2:00 Lunch on your own
2:00 ‐ 2:30 FREE THINK TIME (individual, or self organizing small groups) All
2:30 ‐ 3:15 Report outs from breakout groups (15 mins each) Group Leads
3:15 ‐ 3:30 Plenary Discussion, Selection of Breakout Groups All
3:30 - 4:00 Break
4:00 - 5:30 Break Out Sessions Group Leads
5:30 Workshop Day #4 Ends All
6:00 Dinner at the Athenaeum (with spouses and significant others)

Friday, October 19, 2018

Keck Center - Think Tank, Room 155

Time
Event
Speaker
8:00 - 8:30 Institute Opens - FREE THINK TIME
8:30 - 9:00 Coffee and Refreshments at Keck Center
9:00 - 9:15 Logistics and Team Lead Goals for the Day Michele Judd and Team Leads
9:15 - 10:00

Breakout Groups Report Out

All
10:00 - 10:30 Open Discussion of Breakout Group Recommendations and Group Feedback All
10:30 - 11:00 Break
11:00 - 12:30 Open Discussion of Breakout Group Recommendations and Group Feedback (continued) All
12:30 - 1:30 Lunch at the Institute
1:30 - 2:30 Possible Break Out Groups / Advocacy / Illustrations / Path Forward? All
2:30 - 3:30 Outline of Final Report All
3:30 - 4:00 Break
4:00 - 4:45 Final Study Activities and Assignments - Group Discussion All
4:45 - 5:00 Workshop Closeout Michele Judd
5:00 Workshop Concludes

Workshop Participants:

  • Carver Bierson - UC Santa Cruz
  • Ashley Davies - JPL
  • Katherine de Kleer - Caltech
  • Daniella DellaGiustina - University of Arizona
  • Anton Ermakov - JPL
  • Jim Fuller - Caltech
  • Christopher Hamilton - University of Arizona
  • Camilla Harris - University of Michigan
  • Hamish Hay - University of Arizona
  • Robert Jacobson - JPL
  • James Keane - Caltech
  • Laszlo Kestay - USGS
  • Krishan Khurana - UCLA
  • Karen Kirby - Johns Hopkins Applied Physics Laboratory
  • Valery Lainey - JPL
  • Isamu Matsuyama - University of Arizona
  • Christine McCarthy - Columbia University
  • Alfred McEwen - University of Arizona
  • Francis  Nimmo - UC Santa Cruz
  • Mark Panning - JPL
  • Ryan Park - JPL
  • Anne Pommier – UCSD
  • Julie Rathbun - Planetary Science Institute
  • Gregor Steinbrügge - University of Texas at Austin
  • Dave Stevenson - Caltech
  • Victor Tsai – Caltech
  • Elizabeth Turtle - Johns Hopkins Applied Physics Laboratory