The evolution of the moon

The origin of the moon has been attributed to a giant impact between an asteroid and the early Earth. The heat produced by this event melted a significant part of the moon, resulting in the lunar magma ocean (LMO). Cooling and crystallisation of the LMO over time resulted in the moon we have now, but the steps in between are still debated.

The EU-funded LUNARMAGMAOCEAN (Late-stage evolution of the lunar magma ocean: An experimental study) project aimed to develop new models to explain how the LMO evolved as it crystallised during its late-stage evolution. Data for this study was drawn from observations on surface lavas (the mare basalts) and the GRAIL spacecraft mission, and supplemented by laboratory experiments.

Using furnaces and presses across a range of pressures and temperatures, researchers mimicked the changing conditions of the early LMO. They used sophisticated equipment to control parameters such as starting compositions, temperature and oxygen pressure. Using a stepwise experimental technique built on successive experiments and modelling, the complete evolution of the LMO was reconstructed.

High-pressure experiments provided a clear understanding of the first evolutionary stages of the LMO. The experiments were combined with geochemical modelling to trace the liquid lines of descent during cooling of the moon.

Researchers also completed low-pressure experiments to simulate the later periods of surface cooling, providing the first detailed picture of how the moon's crust formed. This information will be useful to geologists and astronomers alike.