Geological Society of America

T48 Friends of Hoth: Satellites of the Outer Solar System

Sunday, 25 September 2016
1:30 PM - 5:30 PM
Room 201

WHAT HAVE WE LEARNED ABOUT CHARON FROM NEW HORIZONS?

Paper number: T48-4
Program: Technical Sessions
Time: 2:10 PM – 2:30 PM

Authors

W.M. Grundy Presenting Author
Lowell Observatory, Flagstaff, AZ
D.P. Cruikshank
NASA Ames Research Center, Moffett Field, CA
C.M. Dalle Ore
SETI Institute, Mountain View, CA
C.M. Dalle Ore
NASA Ames Research Center, Moffett Field, CA
A.M. Earle
Massachusetts Institute of Technology, Cambridge, MA
K. Ennico
NASA Ames Research Center, Moffett Field, CA
D.E. Jennings
NASA Goddard Space Flight Center, Greenbelt, MD
C.J.Α. Howett
Southwest Research Institute, Boulder, CO
R.I. Kaiser
University of Hawai’i at Manoa, Honolulu, HI
T.R. Lauer
National Optical Astronomy Observatory, Tucson, AZ
I.R. Linscott
Stanford, CA
C.M. Lisse
Johns Hopkins University, Laurel, MD
K.L. Berry
Northern Arizona University and United States Geological Survey, Flagstaff, AZ
A.W. Lunsford
NASA Goddard Space Flight Center, Greenbelt, MD
W.B. McKinnon
Department of Earth and Planetary Sciences and McDonnell Center for the Space Sciences, Saint Louis, MO
J.M. Moore
NASA Ames Research Center, Moffett Field, CA
F. Nimmo
University of California Santa Cruz, Santa Cruz, CA
C.B. Olkin
Southwest Research Institute, Boulder, CO
A.H. Parker
Southwest Research Institute, Boulder, CO
J.Wm. Parker
Southwest Research Institute, Boulder, CO
S. Philippe
Université Grenoble Alpes, CNRS, Grenoble
S. Protopapa
University of Maryland, College Park, MD
E. Quirico
Université Grenoble Alpes, CNRS, Grenoble
R.a. Beyer
NASA Ames Research Center, Moffett Field, CA
H.J. Reitsema
Ball Aerospace (retired), Boulder, CO
D.C. Reuter
NASA Goddard Space Flight Center, Greenbelt, MD
S.J. Robbins
Southwest Research Institute, Boulder, CO
P.M. Schenk
Lunar and Planetary Institute, Houston, TX
B. Schmitt
Université Grenoble Alpes, CNRS, Grenoble
F. Scipioni
NASA Ames Research Center, Moffett Field, CA
M.R. Showalter
SETI Institute, Mountain View, CA
K.N. Singer
Southwest Research Institute, Boulder, CO
J.R. Spencer
Southwest Research Institute, Boulder, CO
J.A. Stansberry
Space Telescope Science Institute, Baltimore, MD
R.P. Binzel
Massachusetts Institute of Technology, Cambridge, MA
S.A. Stern
Southwest Research Institute, Boulder, CO
C.C.C. Tsang
Southwest Research Institute, Boulder, CO
G.L. Tyler
Stanford, CA
O.M. Umurhan
NASA Ames Research Center, Moffett Field, CA
A.J. Verbiscer
University of Virginia, Charlottesville, VA
H.A. Weaver
Johns Hopkins University, Laurel, MD
O.L. White
NASA Ames Research Center, Moffett Field, CA
L.A. Young
Southwest Research Institute, Boulder, CO
A.M. Zangari
Southwest Research Institute, Boulder, CO
V.J. Bray
University of Arizona, Tucson, AZ
M.W. Buie
Southwest Research Institute, Boulder, CO
B.J. Buratti
NASA Jet Propulsion Laboratory, La Cañada Flintridge, CA
A.C. Cheng
Johns Hopkins University, Laurel, MD
J.C. Cook
unaffiliated, Westminster, CO

Abstract

NASA's New Horizons probe explored the Pluto system in 2015. Its instrument suite recorded a trove of data for Pluto's large satellite Charon, most of which has now been transmitted back to Earth. The New Horizons observations revealed Charon to be a complex world in its own right. This talk will give an overview of what has been learned.

There is a striking dichotomy between Charon's smoother southern plains and more rugged northern hemisphere, with the boundary featuring a belt of tectonically broken terrain. These two major provinces are spectroscopically very similar in the near infrared, with H₂O ice absorptions dominating the reflectance spectra in both areas. In the south, small wrinkles and pits hint at a cryovolcanic resurfacing episode. In the north, deep, but highly eroded chasms separate highland blocks, suggesting a global expansion early in Charon's history.

Impact craters are abundant across Charon's encounter hemisphere, but are not saturated, and craters smaller than ~10 km are relatively scarce. Craters exhibit a variety of albedo patterns in their ejecta with some having bright distil rays combined with darker inner ejecta. At least one crater shows an infrared absorption feature attributed to NH₃ice, while other similar-looking craters do not.

Charon's northern polar region is distinctly dark and red compared with lower latitudes. The southern pole is similarly dark. The dark poles are interpreted as resulting from seasonal cold-trapping of escaping gas from Pluto's atmosphere, feeding photolytic production of heavier and less volatile molecules that go on to produce tholin-like macromolecular organics.

Charon's complexities suggest that comparably-sized objects elsewhere in the Kuiper belt are equally fascinating and worthy of exploration.

This work was supported by NASA’s New Horizons project.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-286971

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