Magnificent desolation

Abstract

The perturbation of the orbits of the Lunar Orbiters had shown that the distribution of mass within the Moon was surprisingly lumpy. Although the flight dynamics team believed they had understood this ‘mascon’ effect, Apollo 8 had been perturbed, and if a landing had been attempted then Frank Borman and Bill Anders would have found themselves descending on unfamiliar terrain. The Apollo 10 LM separated, inserted itself into the descent orbit, and followed through to PDI, at which point it shed the descent stage and rehearsed an abort. At this lower altitude, the perturbation was greater, and if Tom Stafford and Gene Cernan had tried to land they too would have come down off target.