Searching for the Moon’s Mantle

We’ve studied and examined the Apollo samples of the lunar maria (pronounced MAR-ee-uh) for thirty years but despite the thorough search of these collections, we have never found a sample of the deep mantle from which these lavas were formed. How might such a deeply seated rock find its way to the surface? Large basin-creating [...]

Red symbols on this map of lunar crustal thickness show where the Kaguya team have identified deposits of olivine
We’ve studied and examined the Apollo samples of the lunar maria (pronounced MAR-ee-uh) for thirty years but despite the thorough search of these collections, we have never found a sample of the deep mantle from which these lavas were formed. How might such a deeply seated rock find its way to the surface? Large basin-creating impacts on the Moon might have dug through tens of kilometers of crust (down into its deepest layers) to excavate samples of the mantle. Another occurrence of mantle samples is as small chunks of rock included in lava. Fragments of rock may be ripped away during the ascent of the dense, liquid magma and become inclusions in the solidified lava flows; these “stranger” rocks are called xenoliths. Despite an exhaustive ...