Studies of asteroids are revealing that they might have a watery history. The DAWN spacecraft orbiting Ceres has provided data that suggests water was a major ingredient in the formation and evolution of the crust and mantle of the dwarf planet. This suggests that water is a much bigger player in the solar system than ever thought before.
A Philadelphia-sized lava tube has been identified on the moon, by the Japanese lunar orbiting satellite Selene. Gravity studies indicated its presence. This is an important discovery because Vice President Pence has indicated that the Trump administration will be far more focused on returning to the moon than with pushing for exploration of Mars. Tubes become important in that they can provide needed shielding of human outposts.