Sydney: A wealth of evidence, provided by lunar rock samples, shows how meteorites struck the moon.
The study, headed by microstructural geology experts Nick Timms and Steven Reddy, professor, Western Australian School of Mines (WASM), documents the discovery of impact-related shock features in lunar zircon.
Timms said they stumbled upon the discovery while looking more closely at lunar zircon mineral grains, with the use of microscopy facilities at Curtin University, the journal Meteoritics and Planetary Science reports.
They found the presence of preserved microscopic details, known as planar deformation features (PDFs), as well as micro-twins (impact indicators), which are only ever produced by large-scale meteorite impacts, according to a WASM statement.
"This research is the first to report the presence of PDFs and micro-twins in lunar zircon, which provide unequivocal evidence of the immense pressures that occur during an impact event," Timms said.
"This research also provides a new explanation of how these features form. As shock waves pass through a rock, fractions of a second after a meteorite impact, these features form like microscopic crumple zones which are caused by directional differences in zircon`s elasticity."
Timms said the research was a step closer to the major scientific goal of establishing the absolute timing of meteorite impact events on the moon, and consequently, the inner solar system.
"The current paradigm for the early impact history of our solar system stems from studies of lunar rocks and involves a period of intense impact events around 3.9 billion years ago, known as the `Late Heavy Bombardment`," he said.