Height-to-diameter ratios of moon rocks from analysis of Lunokhod-1 and -2 and Apollo 11-17 panoramas and LROC NAC images

An analysis is performed of 91 panoramic photographs taken by Lunokhod-1 and -2, 17 panoramic images composed of photographs taken by Apollo 11-15 astronauts, and six LROC NAC photographs. The results are used to measure the height-to-visible-diameter (h/d) and height-to-maximum-diameter (h/D) ratios for lunar rocks at three highland and three mare sites on the Moon. The average h/d and h/D for the six sites are found to be indistinguishable at a significance level of 95%. Therefore, our estimates for the average h/d = 0.6 +/- 0.03 and h/D = 0.54 +/- 0.03 on the basis of 445 rocks are applicable for the entire Moon's surface. Rounding off, an h/D ratio of a parts per thousand 0.5 is suggested for engineering models of the lunar surface. The ratios between the long, medium, and short axes of the lunar rocks are found to be similar to those obtained in high-velocity impact experiments for different materials. It is concluded, therefore, that the degree of penetration of the studied lunar rocks into the regolith is negligible, and micrometeorite abrasion and other factors do not dominate in the evolution of the shape of lunar rocks.