Charon: Geologic Map of New Horizons’ Encounter Hemisphere, IVS.J. Robbins0,1, J.R. Spencer1, R.A. Beyer2,3, P. Schenk4, J.M. Moore3, W.B. McKinnon5, R.P. Binzel6, M.W. Buie1, B.J. Buratti7, A.F. Cheng8, W.M. Grundy9,

I.R. Linscott10, H.J. Reitsema11, D.C. Reuter12, M.R. Showalter2, G.L. Tyler1, L.A. Young1, C.B. Olkin1, K. Ennico3, H.A. Weaver8, S.A. Stern1,the New Horizons Geology & Geophysics Investigation Team, LORRI Instrument Team, MVIC Instrument Team, and the New Horizons Encounter Team

0stuart@boulder.swri.edu, Southwest Research Institute, @DrAstroStu, 1Southwest Research Institute, 1050 Walnut Street, Suite 300, Boulder, CO 80302. 2Sagan Center at the SETI Institute. 3NASA Ames Research Center, Moffett Field, CA 84043. 4Lunar and Planetary Institute, Houston, TX. 5Washington University in St. Louis, St. Louis, MO.6Massachussetts Institute of Technology, Cambridge, MA. 7NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA. 8The Johns Hopkins University, Baltimore, MD. 9Lowell Observatory, Flagstaff, AZ. 10Stanford University, Stanford, CA. 11Ball Aerospace (retired), Boulder, CO. 12NASA Goddard Space Flight Center, Greenbelt, MD.

Units

Ej

Ls

Dm

Mo

Pg

Rt

Sm

Sme

Cr

Linear Featurescrest of crater rim (120)depression margin (20)graben trace (37)groove (506)ridge crest (83)catena (1)

broad warp (15)

scarp base (31)scarp crest (174)

Geologic Contactsmap boundaryboundary, certainboundary, approximate

Surface Features

Crater Ejecta (12)

Landslide (6)

Depressed Material (13)

Mons / Outcrops (55)

Patterned Ground (23)

Rough Terrain (1)Smooth Terrain (2)(“Vulcan Planum” background unit)

Smooth Terrain, Elevated (2)

Crater (120)

Bl Blocky Terrain (1)(“Oz Terra” background unit)

dark-colored ejecta

light-colored ejecta

dark-colored halo

dark-colored mantling

light-colored halo

Linear Features Only Surface Features over Units

Geologic Units and Linear Featuresover LORRI Basemap

Molleweide Projectionprinted scale: ≈1:6M

References &Acknowledgments[1] Cheng, A.F. et al. (2008) Long-Range Reconnaissance

Imager on New Horizons. Space Sci. Rev. 140, 187-215. doi: 10.1007/s11214-007-9271-6.

[2] Reuter, D.C. et al. (2008) Ralph: A Visible/Infrared Imager for the New Horizons Pluto/Kuiper Belt Mission. Space Sci. Rev. 140, 129-154. doi: 10.1007/s11214-008-9375-7.

[3] Schenk, P. et al. (2016) Topography of Pluto and Charon: Impact Cratering. Lunar & Planet. Sci. Conf. 47, Abstract #2795.

[4] Robbins, S.J. et al. (2017) Craters of the Pluto-Charon System. Icarus 287, 187-206. doi: 10.1016/j.icarus.2016.09.027.

[5] Buratti, B. et al. (2017) Global albedos of Pluto and Charon from LORRI New Horizons Observations. Icarus 287, 207-217.doi: 10.1016/j.icarus.2016.11.012.

[6] Grundy, W.M. et al. (2016) The formation of Charon’s red poles from seasonally cold-trapped volatiles. Nature 539, 65-68. doi: 10.1038/nature19340.

[7] Beyer, R.A. et al. (2017) Charon Tectonics. Icarus 287, 161-174. doi: 10.1016/j.icarus.2016.12.018.

[8] Beyer, R.A. et al. (in prep.) The nature and origin of Charon’s Smooth Plains. in prep. for Icarus.

[9] Robbins, S.J. et al. (2018) Investigation into Charon’s craters with abrupt terminus ejecta, comparisons with other icy bodies, and formation implications. JGR 123, 17p. doi: 10.1002/2017JE005287.

This work was funded by NASA’s New Horizons mission.

Data SourcesBasemap: Panchromatic LORRI [1] and MVIC [2] images at up to 160 m/px. Mapping area pixel scale at least 850 m/px. Solar in-cidence and emission angles are non-uniform and this, with non-uniform pixel scale across datasets, complicates mapping.

Topography: Solutions over most of the encounter hemisphere at up to 100 m accuracy, down to 850 m accuracy [3].

Composition: 4-color mosaics from MVIC at 650 and 1500 m/px. Hyperspectral imaging at 5,000 m/px of most of encounter hemisphere, composition maps are in progress to new basemap.

Crater Maps: Craters from [4] and D ≥ 15 km used in this map.

Incidence & Emission Angles

-90

-60

-30

0

30

60

90

Latit

ude

360270180900

Longitude

90

80

70

60

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40

30

20

10

0

Incidence Angle (0°=noon, 90°=terminator)

-90

-60

-30

0

30

60

90

Latit

ude

360270180900

Longitude

90

80

70

60

50

40

30

20

10

0

Emission Angle (0°=directly below

spacecraft)

area in permanent winter for next several decades

area in permanent winter for next several decades

Pixel Scale

-90

-60

-30

0

30

60

90

Latit

ude

360270180900

Longitude

0.1

2

3456

1

2

3

456

10

2

34

Pixel Scale (km/px)

16

14

12

10

8

6

4

2

0

Perc

ent

of S

urfa

ce p

er P

ixel

Sca

le

6 80.1

2 4 6 81

2 4 6 810

2 4

Pixel Scale (km/px)

100

80

60

40

20

0

Cumulative Percent of Surface per Pixel Scale

Histogram Cumulative

19.6% of surface not observedmapping area

area in permanent winter for next several decades

Mapping ProgressAll features have been re-drafted to the latest (final) SPICE solu-tion from mid-2017:

☑ Units map based on images, color, and topography.

☑ Linear features map based on images and topography.

☑ Albedo features map based on images, color, and albedo [5].

In Progress:◻ Refine/iterate chronostratigraphy.◻ Iterate on feature interpretation.

Related WorkSeveral published or in prepara-tion related works will be incorpo-rated into map interpretation:﹅ Charon’s red pole [6]﹅ Charon’s tectonics [7]﹅ Charon’s “Vulcan Planum” [8]﹅ Charon’s crater ejecta [9]

Mapping DetailsGlobal

Approximate Map Area: 60% of disk*

Full Map Scale: 1:3Mprinted map 50”

Mapping Scale (3×): 1:1MVertex Spacing: 1 km (⅓ cm)Min. Crater: 15 km (½ cm)Min. Feature Length: 9 km (⅓ cm)Min. Unit: 30 km2

Min. Albedo Feature: 50 km2

*Map area covers images taken within a few hours of closest approach and closely corre-sponds with the areas imaged at ≲1 km/px. Southern margin of “map boundary” corre-sponds to terminator and is not fully reflected in incidence / emission angle and pixel scale maps. Area is ≈3,800,000 km2.