Roughness of the lunar soil

Three stereoscopic close-up photographs taken of the lunar surface by Apollo 11 and 12 astronauts were analyzed to investigate the roughness of the lunar soil at millimeter resolution. Most existing measurements of regolith roughness were based on radar measurements at wavelengths of about 8.6 mm. Several statistical parameters were determined for they landing site. The surace roughness has been found to be nearly Gaussian. The rms slopes were obtained over scales between 0.5 mm and 5 cm. They steadily decrease with increasing scale length from 58 deg to 2 deg and are in reasonable agreement with radar-measured values. The autocorrelation coefficient of the height distribution has also been obtained; it has a scale length of 0.7 mm.