Roadmaps to Ocean Worlds (ROW): Trans-Neptunian objects

Bonnie Buratti, Kelsi Singer, Amanda Hendrix, and the ROW Team SBAG

June 13, 2017

NASA funding acknowledged All images NASA

Background: 1. Congressional directive

“[Congress] directs NASA to create an Ocean World Exploration Program whose primary goal is to discover extant life on another world using a mix of Discovery, New Frontiers and Flagship class missions consistent with the recommendations of current and future Planetary Decadal surveys.” ROW included Ceres, Pluto and TNOs in general in its definition of Ocean Worlds. With a large team led by Amanda Hendrix and Terry Hurford, ROW produced a Goals, Objectives, Investigations (GOI) Report in order to identify and characterize ocean worlds, evaluate their habitability, and search for life

Background: 2. OPAG (SBAG) charge to ROW Team

• Identify and prioritize science objectives for Ocean Worlds (tied to the Decadal Survey)

• Design roadmap to explore these worlds to address science objectives - Include mission sequences, sustained exploration effort • Assess where each Ocean World fits into the overall roadmap • Summarize broad mission concepts - Consider mission dependences & international cooperation • Recommend technology development and detailed mission studies in

support of the next decadal survey • Place exploration of Ocean Worlds into the larger context of Solar

System exploration

Ocean on Pluto • A single flyby such as that of New

Horizons isn’t capable of determining whether Pluto has a subsurface ocean.

• Existence of subsurface ocean on Pluto is based on theoretical modeling that computed heating from rock/radioactive isotope fractions; ocean’s existence is uncertain

• Some nearly crater-free surfaces on Pluto that are most likely made of water ice (Wright Mons and the plateau to the west) also suggest a possible internal ocean

• Note that Pluto and Charon differentiated after formation as their densities are similar

Owen et al. 1993; Hussman et al., 2006; Robuchon and Nimmo, 2011; Kimura et al., 2017; McKinnon et al., 2017

Interior of Pluto

Charon: obvious melting

Evidence for other Ocean Worlds in the Kuiper Belt

• High albedos near unity have been indicators of activity on planets and moons, such as as is the case for Enceladus (Buratti et al., 1984; Verbiscer et al., 2005). A possible liquid ocean on Pluto was based on models that computed heating from rock/radioactive isotope fractions. Density of Pluto is 1.9 gm/cc, and near-unit albedo on Sputnik Planitia was discovered by New Horizons (Stern et al., 2015)

• Eris: The density of Eris is even larger (2.5 gm/cc), and its geometric albedo is 1.0 (Sicardy et al., 2011). These results suggest Eris likely has current cryovolcanic activity on its surface

• Other explanations are possible, such as condensation of CH4 frost without the “tholins” that Pluto has, for example.

• Many binaries in the Kuiper Belt may provide tidal heating

• Relatively high densities of KBOs indicate radioactive nuclides for heat source.

Eris and Dysnomia Enceladus

Pluto

Progress on Science Questions

Progress on Mission Design

– ROW Townhall at LPSC in March 2017 and Vision 2050 Workshop – Within ROW, collation and vetting mission concepts and measurements needed to address science questions and to put into Ocean Worlds Missions Scenarios, Roadmaps & Technologies document – A draft Goals, Objectives and Investigations (GOI) document has been posted on the OPAG/ROW website for initial feedback -- Ultimately the ROW documents will be provided to the Decadal mid-term review committee and to the next Decadal Survey group to hopefully influence them to advocate for an Ocean Worlds program, which includes TNOs

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