REVISITING APOLLO TRAVERSES WITH LROC NAC DTM SLOPE MAPS

High-resolution digital terrain models (DTMs) allow us to revisit the Apollo rover traverses from a new perspective. Using geometric stereo observations acquired from the Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC), the LROC Science Operations Center team has created DTMs [1] covering the landing sites and traverse areas for the Apollo 15, 16, and 17 missions. These DTMs have pixel scales of 2-5 m and have precisions better than their pixel scales. They have vertical accuracies of < 1 m relative to co-located Lunar Orbiter Laser Altimeter tracks, and are horizontally accurate to within 5 m relative to the Apollo Lunar Surface Experiment Package central stations. For Apollo 15 and 16, a single NAC stereo image pair is sufficient to cover the landing site and traverse region; for Apollo 17, several DTMs are mosaicked together.

Using slope maps derived from these DTMs, along with digitized maps of the rover traverse routes for each mission [2], we extract the slopes of the terrain along the routes to create three dimensional maps of these traverses. This allows us to evaluate the chosen routes for the hazards they posed. It also allows us to compare astronaut commentary from those traverses [3] to our quantitative data. We further re-examine the topography of the regions to compare the historical routes to optimal traverse paths between stations found using the high-resolution topographical data now available.

[1] Henriksen, M. R. et al. (2017) Icarus 283, 122-137. [2] Stooke, P. J. (2018) LPSC XLIX, #1007. [3] Jones, E. M. (2015) Apollo Lunar Surface Journal. https://www.hq.nasa.gov/alsj/.