IN 1989 VOYAGER 2 ENCOUNTERED THE NEPTUNE SYSTEM AND RETURNED IMAGES OF ITS LARGEST MOON (~1350 KM RADIUS) TRITON AND THESE IMAGES REMAIN THE PRIMARY DATA FOR OUR UNDERSTANDING OF THE SATELLITE (FIG. 1). TRITON WAS REVEALED TO BE A GEOLOGICALLY ACTIVE MOON [SMITH ET AL. 1989] AND ITS ACTIVITY HAS BEEN LINKED TO ITS DYNAMICAL HISTORY AS A CAPTURED KUIPER BELT OBJECT (KBO) [E.G. MCKINNON ET AL. 1995]. UNTIL THE NEW HORIZONS MISSION FLEW BY PLUTO IN 2015 TRITON WAS THE ONLY KBO VISITED BY SPACECRAFT; HOWEVER TRITONS ROLE AS OUR ONLY CLOSE-UP EXAMPLE OF A PROBABLE KBO WAS ALWAYS DOGGED BY THE QUESTION OF WHETHER ITS GEOLOGY WAS REPRESENTATIVE OF OTHER KBOS OR RESULTED FROM ITS UNIQUE HISTORY. THAT QUESTION HAS NOT YET BEEN RIGOROUSLY REASSESSED IN THE POST PLUTO-ENCOUNTER ERA. ADDITIONALLY TRITON BRIDGES A GAP BETWEEN KBOS AND ICY SATELLITES. AS A LIKELY KBO CAPTURED INTO NEPTUNE S ORBIT [E.G. MCKINNON ET AL. 1995] IT CONTRIBUTES TO THE DIVERSE POPULATION OF ICY SATELLITES BUT ITS ORIGIN IS UNIQUE RELATIVE TO THOSE OF THE ICY SATELLITES AND LIKELY CONTRIBUTES TO ITS YOUNG SURFACE AND EXOTIC TERRAINS (FIG. 2) [SCHENK&JACKSON 1993]. THE CAPTURE OF TRITON BY NEPTUNE LIKELY RESULTED IN A MASSIVE HEATING EVENT THAT RESULTED IN RESURFACING [MCKINNON 1984; 1992] POSSIBLY BY CRYO-VOLCANISM [CROFT 1990; SCHENK 1992]. CRATER COUNTS FOR BOTH TRITON [SCHENK&ZAHNLE 2007] AND PORTIONS OF PLUTO [STERN ET AL. 2015] SUGGEST THAT BOTH SURFACES ARE EXCEPTIONALLY YOUNG WHICH MAY INDICATE THAT NEITHER TRITON NOR PLUTO RETAIN THEIR ORIGINAL SURFACES. THE SUCCESSFUL NEW HORIZONS FLYBY THROUGH THE PLUTO SYSTEM OPENED THE DOOR TO ANOTHER PART OF THE SOLAR SYSTEM REVEALING AN EXTRAORDINARY DIVERSITY OF TERRAINS RENEWING INTEREST IN THE ORIGIN EVOLUTION AND DIVERSITY OF KBOS [STERN ET AL. 2016] AND BY EXTENSION TRITION. VOYAGER 2 S ENCOUNTER WITH TRITON AND NEPTUNE OCCURRED ON AUGUST 25 1989 WITH CLOSEST APPROACH TO TRITON OF 39 800 KM [CHAPMAN&CRUIKSHANK 1995; STONE&MINER 1989] BUT THE INHERENT CHALLENGE WITH FLYBY MISSIONS ESPECIALLY IN THE OUTER SOLAR SYSTEM MEAN EXTREMELY LIMITED DATA SETS WITH LONG TIME LAPSES BETWEEN MISSIONS. THESE OBSTACLES ARE OVERCOME BY CREATIVE SOLUTIONS FOR MAXIMIZING THE DATA RETURN INCLUDING DETAILED GEOLOGIC MAPPING AND GENERATION OF DIGITAL ELEVATION MODELS (DEMS) FROM OFTEN NON-TARGETED STEREO PAIRS. WE PROPOSE TO PRODUCE A COMPLETE FRAMEWORK OF ACCESSIBLE DATA PRODUCTS AND ESTABLISH THROUGH MAPPING A GEOLOGICAL FOUNDATION TO FACILITATE AND FOSTER THE RESURGING INTEREST IN TRITON AND KBOS. WE PROPOSE TO CREATE A USGS GLOBAL-SCALE GEOLOGIC MAP OF TRITON TO INFORM ONGOING AND FUTURE EXPLORATION OF TRITON AND OTHER KBOS. ADDITIONALLY WE AIM TO RESTORE AND ARCHIVE VOYAGER 2 DATA PRODUCTS THAT EXIST ONLY ON COMPACT DISKS (CDS) AT THE USGS ASTROGEOLOGY SCIENCE CENTER. ADDITIONALLY WE PROPOSE TO PRODUCE A COMPREHENSIVE AND COMPLETE SET OF HIGH-LEVEL (PROCESSED) TRITON DATA PRODUCTS THAT MAXIMIZE THE LIMITED DATA SET RETURNED FROM THE VOYAGER 2 FLYBY ENCOUNTER AND MAKE THEM READILY AVAILABLE TO THE COMMUNITY.
$142,433FY2017National Aeronautics and Space AdministrationNASA
Smithsonian Institution, Washington DC