A 160-mile-wide asteroid with a dense iron core struck the Moon at a shallow angle, explaining the unique shape of its largest impact basin.
Shaping the South Pole-Aitken Basin
A new study indicates that the Moon's largest impact basin, the South Pole-Aitken (SPA) basin, was likely created by a differentiated asteroid. Using high-resolution 3D simulations, researchers found that the basin's tapered-ellipse shape is best explained by a specific kind of cosmic collision.
Key Simulation Findings
The impactor measured 160 miles across and featured a dense iron core encased in a rocky mantle. It struck the lunar surface at a shallow 30-degree angle, traveling at approximately 8 miles per second.
This unique trajectory caused a dramatic effect: the impactor's upper layers sheared off while the core continued forward, producing the basin's elongated, tapered shape.
Implications for Artemis Missions
The impact would have ejected material from the Moon's mantle toward the south pole, the very region where NASA's Artemis missions plan to land. Samples from that region could help determine the basin's age and reveal the composition of the Moon's deep interior.