Improved LOLA elevation maps for south pole landing sites: Error estimates and their impact on illumination conditions

We present new high-resolution topographic models of 4 high-priority lunar south pole landing sites based exclusively on the laser altimetry data acquired by the Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter. By iteratively adjusting the LOLA tracks to the LOLA-based digital elevation model (LDEM) in a self-consistent fashion, we reduce the orbital geolocation errors by over a factor of 10 such that the new ground track geolocation uncertainty is similar to 10-20 cm horizontally and similar to 2-4 cm vertically over each 16 x 16 km region. These new and improved 5 m/pix LDEMs will be useful to constrain higher-resolution topographic models derived from imagery, which are not as well controlled geodetically and which can be hindered by shadows. We developed a method to estimate surface height uncertainty in the new LDEMs, which accounts for the reduced orbital errors and interpolation errors by assuming a fractal behavior for the short-scale topography. The LDEM surface height and slope uncertainties have typical RMS values of similar to 0.30-0.50 m and similar to 1.5-2.5 degrees, respectively. Finally, we examine how height uncertainties propagate to variations in horizon elevation and thus the predicted illumination conditions at these polar latitudes, and we show how this error characterization can inform landing site studies.

Automated summary

New high-resolution topographic models of lunar south pole landing sites based on LOLA data have reduced geolocation errors significantly. The uncertainties in surface height and slope in the new LDEMs have typical RMS values of 0.30-0.50 m and 1.5-2.5 degrees, respectively.