The NASA Lunar Reconnaissance Orbiter is 5 years into its mission to “help the world develop a deeper understanding of the lunar environment” and pave the way for mans return to the moon. Maybe even in a more permanent role.
This video released last week outlines many of the discoveries made since launch in 2009, highlighting a variety of ‘hole’ structures. A number of these have been found in the dark lunar maria, ‘seas’ of ancient volcanic activity. Ranging from 5-900m diameter, they widen underground and are though to be the collapsed ceiling of lava tubes. Other pits are formed from meteorite impacts.
The suggestion of the NASA video is that these areas will be suited to prolonged human settlements as they offer protection from radiation and further meteorite impacts. Living underground has the benefit of more stable temperatures as well, though we’ve made use of that since the birth of man right here on earth.