SPACE: Grail satellite analysis indicates lava tubes on the moon could be up to 1000 to 5000 meters wide which would be ideal sites for massive moon colonies. “Lunar lava tubes may potentially serve a role as enclosures for human habitats. Tunnels up to 5000 meters in diameter may exist, lying under 40 to 500 meters (130 ft) or more of basalt with a stable temperature of −20 °C (−4 °F). These natural tunnels provide protection from cosmic ray radiation, meteorites, micrometeorites, and ejecta from impacts. They are shielded from the variations in temperature at the lunar surface, which would provide a stable environment for inhabitants. Lunar lava tubes are typically found along the boundaries between lunar mares and highland regions. This would give ready access to elevated regions for communications, basaltic plains for landing sites and regolith harvesting, as well as underground mineral resources.”