The Pluto System After New Horizons (PSANH) conference was held at the Johns Hopkins Applied Physics Laboratory in Laurel, Maryland, on July 14–18, 2019. The conference provided an opportunity to summarize our understanding of the Pluto system and the Kuiper belt following the New Horizons encounters with Pluto and 2014 MU₆₉ (nicknamed “Ultima Thule”). Contributions spanning all relevant research on the Kuiper belt, including both observations and theory, were presented.

The conference began with a reception on July 14 to celebrate the fourth anniversary of the New Horizons flyby of Pluto. Scientific sessions filled the next four days with a mix of invited reviews and contributed oral presentations. The morning and evening oral sessions were organized according to the following themes: Pluto Geology, Pluto Composition, Charon, Pluto’s Small Satellites, Pluto Atmosphere (including haze), Pluto Climate, MU₆₉ and KBOs, Potential Future Missions to Pluto and the Outer Solar System, and Origins. For each theme, a panel discussion followed the individual presentations to delve deeper into each subject and to identify any remaining unresolved issues. A two-hour poster session spanning all the scientific themes was held on the afternoon of July 16.

The invited reviews at the conference form the basis for the chapters in a new book being prepared to summarize our current understanding of the Pluto system and the Kuiper belt, following the discoveries and insights provided by both the New Horizons mission and ongoing remote sensing observations. This book will be part of the Space Science Series published by the University of Arizona Press in collaboration with the Lunar and Planetary Institute and will be the successor to the “Pluto and Charon” volume published in 1997.

The results from the New Horizons mission revolutionized our view of the Pluto system, but those findings provide only a snapshot in time of a very dynamic place. Fortunately, the New Horizons results also provide ground truth for ongoing remote sensing observations, informing the interpretation of their results. Hopefully, this rich “third zone” of the solar system will continue to be explored in the years ahead by both in situ spacecraft and ever more sophisticated remote sensing facilities.

For more information about the PSANH conference, including links to the program and abstracts, visit the meeting website at https://www.hou.usra.edu/meetings/plutosystem2019/.

— Summary provided by Hal Weaver