PSRD: Recent Gas Escape from the Moon

The Moon is generally thought to be geologically inactive, except for being pummeled by meteoroids of various sizes. The youngest returned igneous rocks are about 3 billion years old, although crater counting suggest some lava flows as young as a billion years. However, Peter Schultz (Brown University), Matthew Staid (Planetary Sciences Institute, Tucson), and Carlé Pieters (Brown University) report an array of data that indicate that the Moon may be active enough inside to occasionally spew puffs of gases that blow off the fine-grained, busted up surface materials known as the regolith. The researchers studied a feature called the Ina structure, a depression containing numerous steep-sided hills, located in a mare region known as Lacus Felicitatis. Ina is fresh in appearance both photographically and spectrally. Calibration of crater counts and spectra with other craters dated by cosmochemists using Apollo lunar samples indicate that Ina could be as young as 1 million years.