Free-air gravitational anomalies (red = mass excess; blue = mass deficit) and a shaded topographic relief of the Moon’s Orientale impact basin. This gravitational field model, based on measurements acquired from the NASA GRAIL mission, shows the detailed structure of the central basin depression that is filled with dense mare basalts, as well as the rings that formed due to gravitational collapse of the initial crater cavity shortly after the impact. Image courtesy of Ernest Wright/NASA/GSFC Scientific Visualization Studio

Free-air gravitational anomalies (red = mass excess; blue = mass deficit) and a shaded topographic relief of the Moon’s Orientale impact basin. This gravitational field model, based on measurements acquired from the NASA GRAIL mission, shows the detailed structure of the central basin depression that is filled with dense mare basalts, as well as the rings that formed due to gravitational collapse of the initial crater cavity shortly after the impact. Image courtesy of Ernest Wright/NASA/GSFC Scientific Visualization Studio

An international team of scientists led by researchers at the Massachusetts Institute of Technology have reconstructed the extreme collision that created one of the Moon’s largest craters 3.8 billion years ago, as reported by the University of Hawai‘i.

Jeffrey Taylor, a professor in the UH Mānoa School of Ocean and Earth Science and Technology, was among the scientists who retraced the Moon’s dramatic response in the first hours following the massive impact, and identified the processes by which large, multi-ring basins can form in the aftermath of such events.

The findings, published in two papers in the journal Science, may shed light on how giant impacts shaped the evolution of the Moon, and even life on Earth, shortly after the planets formed.

The team’s results pertain to the Moon’s Orientale Basin, an expansive, bull’s eye-shaped depression on the southwestern edge of the Moon, just barely visible from Earth. The basin is surrounded by three concentric rings of rock, the largest one stretching 580 miles across — about six times as wide as the Big Island of Hawaiʻi. Until now, it’s been unclear how massive impacts produced the complex structures displayed by multi-ring basins.

Probes on NASA’s Gravity Recovery and Interior Laboratory (GRAIL) spacecraft took measurements of the basin’s gravity field at high spatial resolution, providing scientists with a precise map of the Moon’s interior mass distribution which enabled the researchers to make revealing geophysical observations and develop a computer model to re-create the impact and its effects.

Taylor’s role in the mission focused on integrating information about the composition of the crust in and around the Orientale Basin into the interpretation of the gravity data.

“In short, using orbital remote sensing data, I helped put these amazing geophysical observations and computer modeling into a mineralogical and geochemical context,” Taylor said.

Measured impact

In one of two Science papers, Maria Zuber, vice president for research and the E.A. Griswold Professor of Geophysics at MIT and her colleagues analyzed GRAIL’s gravity field measurements and were able to solve a key mystery, namely, the size and location of the basin’s transient crater, which is the initial depression created when an asteroid blasts material out from the lunar surface.

The researchers determined that the 3.8-billion-year-old basin was created by a huge impactor that punched an initial, transient crater into the lunar surface, measuring up to 285 miles in diameter. This impact, the researchers calculated, sent at least 816,000 cubic miles of pulverized lunar crust flying out from the impact site — an amount equivalent to 135 times the co