07.05.2011 - The Lunar Orbiter Laser Altimeter (LOLA) aboard the Lunar Reconnaissance Orbiter (LRO) sends laser pulses down to the surface of the Moon from the orbiting spacecraft. These pulses bounce off of the Moon and return to LRO, providing scientists with measurements of the distance from the spacecraft to the lunar surface. As LRO orbits the Moon, LOLA measures the shape of the lunar surface, which includes information about the Moon's surface elevations and slopes.
LOLA's laser pulse is split into 5 separate beams that hit the lunar surface in a cross-shaped pattern. The reflected pulses from these beams provide 5 parallel profiles along the surface directly beneath LRO. This pattern allows scientists to calculate slopes on the surface of the Moon in a variety of directions on scales of approximately 25 meters.
This image shows the slopes found near the south pole of the Moon, poleward of 75 degrees South. The bright red to white areas have the highest slopes (25 degrees or more) while the dark blue to purple areas have the lowest slopes (5 degrees or less). The steepest slopes are found in impact crater rims, which appear as brightly colored circular features throughout the image.
 Smith, D. E., et al., 2010. The Lunar Orbiter Laser Altimeter Investigation on the Lunar Reconnaissance Orbiter Mission. Space Sci. Rev. 150: 209-241.
 Rosenburg, M. A., et al., 2011. Global surface slopes and roughness of the Moon from the Lunar Orbiter Laser Altimeter. J. Geophys. Res., 116, E2, E02001.