The porosity of the moon's crust reveals the history of bombardment
About 4.4 billion years ago, the early solar system resembled a game of space rock dodgeball, such as large asteroids and comets, and, later, smaller rocks and galactic debris hit the moon and other terrestrial baby bodies. This period ended about 3.8 billion years ago. On the moon, this turbulent time leaves a heavily cratered surface, and a cracked and porous crust. Now MIT scientists have discovered that the porosity of the moon’s crust, which reaches deep below the surface, can reveal a lot about the history of lunar bombardment. In a study appearing today in Nature Geoscience, the team has shown through simulations that, at the start of the bombardment period, the moon was highly porous — nearly a third as porous as pumice. This high porosity is likely the result of an early and massive impact that destroyed much of the crust. Scientists assume that a continuous onslaught of impacts will slowly build up porosity. Surprisingly, however, the team found that nearly all of the moo