Glass on Moon Tells Earth Impact Stories

An international collaboration between researchers from Australia, China, USA, UK, and Sweden has found evidence that asteroid impacts on the Moon coincided with some of the largest meteorite impacts on Earth. Lead author Professor Alexander Nemchin, from Curtin University’s Space Science and Technology Centre (SSTC) in the School of Earth and Planetary Sciences, said the findings imply that the timing and frequency of asteroid impacts on the Moon may have been mirrored on Earth, telling us more about the history of the evolution of our own planet.  

The Curtin University-led research team studied lunar glass found in soil brought back to Earth in December 2020 as part of the Chinese National Space Agency’s Chang’e-5 Lunar mission. The microscopic pieces of glass formed on the Moon due to the heat and pressure of lunar impacts. This glass can be dated using U-Pb (Uranium-Lead) dating methods, which measure the amount of lead within a mineral created by the radioactive decay of uranium. It can be used to date rocks between 1 million to over 4.5 million years old. Using this method led the researchers to their surprising conclusion when they compared these dates with those of major meteoroid impacts on Earth.

“We combined a wide range of microscopic analytical techniques, numerical modelling, and geological surveys to determine how these microscopic glass beads from the Moon were formed and when,” Professor Nemchin said.

“We found that some of the age groups of the lunar glass beads coincide precisely with the ages of some of the largest terrestrial impact crater events, including the Chicxulub impact crater responsible for the dinosaur extinction event.

“The study also found that large impact events on Earth such as the Chicxulub crater 66 million years ago could have been accompanied by a number of smaller impacts. If this is correct, it suggests that the age-frequency distributions of impacts on the Moon might provide valuable information about the impacts on the Earth or inner solar system.”

Co-author Associate Professor Katarina Miljkovic, also from Curtin’s SSTC, said future comparative studies could give further insight into the geological history of the Moon.

“The next step would be to compare the data gleaned from these Chang’e-5 samples with other lunar soils and crater ages to be able to uncover other significant Moon-wide impact events which might, in turn, reveal new evidence about what impacts may have affected life on Earth,” Associate Professor Miljkovic said.