Charon: Geologic Map of New Horizons’ Encounter Hemisphere, III

S.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

Tectonics Map Geologic Contacts Mapping Details map boundary boundary, certain Global boundary, approximate Approximate Map Area: 60% of disk* Linear Features Full Map Scale: 1:3M printed map 50” crest of buried crater crest of crater rim Mapping Scale (6×): 1:500,000

depression margin colors used only in tectonics map Vertex Spacing: 2.5 km (⅘ mm) graben trace Min. Crater: 30 km (1 cm) groove ridge crest Min. Feature Length: 15 km (½ cm) catena Min. Unit: 250 km2 scarp base *Map area covers images taken within a few scarp crest hours of closest approach and closely corre- broad warp sponds with the areas imaged at ≲1 km/px. Southern margin of “map boundary” corre- example of offset due to different versions sponds to terminator topography and is not fully of the basemap being used; all lines must Surface Features reflected in incidence / emission angle and pixel be redrafted to the same, most recent solution “Vulcan Planum” Map dark-colored ejecta scale maps. Area is ≈2,800,000 km2. light-colored ejecta Vulcan Planum (informal name) Units Approximate Map Area: 485,000 km2 Cr Crater Scale: 1:500,000 Crb Buried Crater Mapping Scale: 1:100,000

Ej1 Ejecta Type 1 Vertex Spacing: 2.5 km

Ej2 Ejecta Type 2 Min. Crater: 15 km (3 cm) Min. Feature Length: 5 km (1 cm) Ls Landslide Min. Unit: 50 km2 Dm Depressed Material • Basemap control as of March 2017, and Map reflects Jan- uary 2016 SPICE solutions. Mo1 Mons Type 1 • Basemap is LORRI mosaic Mo2 Mons Type 2 with merged MVIC scan. Mapping Progress Pg1 Patterned Ground Type 1 • Line art is being redrafted Done: Mapped global tectonics with March 2017 SPICE solu- Pg2 Patterned Ground Type 2 tions, and being expanded [5] and Vulcan Planum area [6] northward. Rt Rough Terrain using SPICE from Sept. 2016.

Sm Smooth Terrain In Progress: Redrafting to March 2017 SPICE; extending map Sme Smooth Terrain, Elevated northwards based on albedo rather than topography. To Do: • Merge shadow/topography-based

Data Sources Incidence & Emission Angles Pixel Scale Scale Pixel per Surface of Percent Cumulative map (south) with albedo (north) 90 16 100 Basemap: Panchromatic LORRI 90 Histogram map units if possible 14 Cumulative [1] and MVIC [2] images at up to 80 90°=terminator) (0°=noon, Angle Incidence 19.6% of surface not observed • Incorporate topography and min- 60 mapping area 80 160 m/px. Mapping area pixel 70 12 eralogy 30 60 • Develop chronostratigraphy. scale at least 850 m/px. Solar in- 10 60 50 cidence and emission angles are 8 0

Latitude 40 non-uniform and this, with 6 40 30 References & -30 non-uniform pixel scale across 4 datasets, complicates mapping. 20 20 Acknowledgments

-60 Percent of Surface per Pixel Scale 2 area in permanent winter for next several decades 10 Topography: Solutions over most [1] Cheng, A.F. et al. (2008) Long-Range Re- 0 0 0 -90 6 8 2 4 6 8 2 4 6 8 2 4 connaissance Imager on New Horizons. of the encounter hemisphere at 0 90 180 270 360 0.1 1 10 Space Sci. Rev. 140, 187-215. doi: Longitude Pixel Scale (km/px) 10.1007/s11214-007-9271-6. up to 100 m accuracy, down to [2] Reuter, D.C. et al. (2008) Ralph: A Visible/In- 90 90 90 4 frared Imager for the New Horizons Plu- 850 m accuracy [3]. 3 to/Kuiper Belt Mission. Space Sci. Rev. , Emission Angle (0°=directly below spacecraft) below (0°=directly Angle Emission 140 80 2 129-154. doi: 10.1007/s11214-008-9375-7. 60 60 Composition: 4-color mosaics 70 [3] Schenk, P. et al. (2016) Topography of Pluto 10 and Charon: Impact Cratering. Lunar &

6 (km/px) Scale Pixel from MVIC at 650 and 1500 30 60 30 5 Planet. Sci. Conf. 47, Abstract #2795. 4 3 [4] Robbins, S.J. et al. (2017) Craters of the m/px. Hyperspectral imaging at 50 2 Pluto-Charon System. Icarus 287, 187-206. 0 0 doi: 10.1016/j.icarus.2016.09.027. 5,000 m/px of most of encounter Latitude 40 Latitude 1 [5] Beyer, R.A. et al. (2017) Charon Tectonics. hemisphere, composition maps 30 6 -30 -30 5 Icarus 287, 161-174. doi: 4 10.1016/j.icarus.2016.12.018. are in progress to new basemap. 20 3

2 [6] Beyer, R.A. et al. (in prep.) Geology of Char- -60 -60 on’s Smooth Southern Plains. in prep. for area in permanent winter for next several decades 10 area in permanent winter for next several decades Crater Maps: Craters from [4] 0.1 Icarus. 0 and D ≥ 15 km used in this map. -90 -90 0 90 180 270 360 0 90 180 270 360 This work was funded by NASA’s New Horizons

Longitude Longitude mission.

[email protected], 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.