THE GEOLOGY OF THE APOLLO 17 TAURUS-LITTROW SITE IN LIGHT OF LRO IMAGERY

The Apollo 17 astronauts documented and sampled the geology of the Taurus-Littrow Valley on the Moon, December 11-14, 1972. Low resolution and sun-angle variations in the pre-mission Lunar Orbiter and Apollo 15 photography both limited the level of detail for exploration planning. For example, only one large boulder (Station 6) at the base of either valley wall could be detected. Uncertainty also existed as to the impact or volcanic origin of Shorty Crater (Station 4) and the ejecta or avalanche origin of the light mantle deposit (Stations 2 and 3). New high-resolution images and synthetic aperture radar data from the Lunar Reconnaissance Orbiter (LRO) provide an opportunity to gain new insights about the geology of the region as well as to assess the quality of original exploration planning. Preliminary examination of LRO data raises the following questions:

• Is the dark area on the valley floor north of the Lunar Module Challenger site a concentration of dark pyroclastics or a slope induced photometric effect?
• Can stratigraphic sampling of the North and South Massifs be accomplished using tracks from boulders at the base of the Massifs?
• Can regolith stratigraphy and thickness be mapped combining new data and surface observations on impact crater morphology such as benches, pit craters, boulder and pyroclastic ejecta distribution, etc.?
• Can the original contacts of the "light mantle" avalanche deposit be mapped by fresh crater ejecta brightness at the meter scale?
• Can original flow patterns in the "light mantle" avalanche deposit be mapped with multiple sun angles images and radar data?
• Can the total thrust distance and relative age of the Lee-Lincoln fault be refined?
• Is there a second, buried thrust fault scarp east and parallel to the Lee Lincoln fault?
• Can displacement that creates the moat, including Nansen crater, between the valley basalt fill and the base of the South Massif be quantified?
• Do the low contrast (relative to other Apollo sites) astronaut tracks reflect the local composition or maturity of the regolith?

Apollo 17’s pre-mission field geological plans appear to have been very good. Modifications suggested are 1) integration of the investigation of boulders with tracks from specific levels of the North Massif and 2) sampling the possible pyroclastic area north of the Challenger.