Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars

TLDR

The paper aims to describe the Mars Orbiter Laser Altimeter’s function and its role in producing global topographic and surface property datasets. The authors processed and corrected laser altimeter observations, converting them into gridded and spherical harmonic models that yield a 1 × 2 km resolution topographic grid with ~1 m vertical accuracy and 100 m spatial accuracy for pulse locations. These measurements produce a global topographic grid, 100 m‑scale surface roughness and 1.064‑μm reflectivity maps with 5 % accuracy, and improve Mars’s geodetic grid by two orders of magnitude.

Abstract

The Mars Orbiter Laser Altimeter (MOLA), an instrument on the Mars Global Surveyor spacecraft, has measured the topography, surface roughness, and 1.064‐μm reflectivity of Mars and the heights of volatile and dust clouds. This paper discusses the function of the MOLA instrument and the acquisition, processing, and correction of observations to produce global data sets. The altimeter measurements have been converted to both gridded and spherical harmonic models for the topography and shape of Mars that have vertical and radial accuracies of ∼1 m with respect to the planet's center of mass. The current global topographic grid has a resolution of 1/64° in latitude × 1/32° in longitude (1×2 km 2 at the equator). Reconstruction of the locations of incident laser pulses on the Martian surface appears to be at the 100‐m spatial accuracy level and results in 2 orders of magnitude improvement in the global geodetic grid of Mars. Global maps of optical pulse width indicative of 100‐m‐scale surface roughness and 1.064‐μm reflectivity with an accuracy of 5% have also been obtained.