For years we've designed structures that would allow us to live on either the Moon or Mars. Would they be inflatable? Would they be domes? Apparently, they wouldn't be either — a network of caves could exist on both celestial bodies that would allow us to move in.
From Heinlein's The Moon is a Harsh Mistress to Bear's Moving Mars, both rocks have had their insides populated by colonists at one point or another in science fiction. With the discovery of a network of tunnels, however, things could get a lot easier.
"Over the past year, NASA's Lunar Reconnaissance Orbiter (LRO) has photographed unusual "pit craters" that poke into the moon's crust for hundreds of feet," writes Ray Villard for Discovery. "These are thought to be the collapsed ceilings of underground lava tubes that crisscross the moon as lunar rilles."
How deep or how extensive the pockets are is still anyone's guess, but Villard posits that a similar network could also exist on Mars: "Mars orbiter photos reveal skylight holes on the flanks of the giant shield volcano Olympus Mons. More can be found along the southeast flank of neighboring Arsia Mons, as well as on the sides of the northern shield volcano Alba Patera."
Living in "lava tubes," as Villard calls them, would hopefully eliminate a lot of the barriers designers face when trying to come up with a living solution that would be enclosed, lightweight enough to transport into space and durable enough to protect against tiny meteor strikes and the like. In tunnels, colonists would have the planet itself to shield them.
Pretty wild, right? I'd sign up for a ticket to the Martian tunnels. Oh yeah, and happy forty-first anniversary of the Apollo 11 moon landing.