The Moon and Mars will probably be the first places in the Solar System that humanity will try to live after leaving the safety and security of Earth. But those worlds are still incredibly harsh environments, with no protection from radiation, little to no atmosphere, and extreme temperatures. Living on those worlds is going to be hard, it’s going to be dangerous. Fortunately, there are a few pockets on those worlds that’ll make it a tiny little bit easier to get a foothold in the Solar System: lava tubes.