Universe's Edge

The Saturn Expedition left a massive rift and moon dust in its wake. The Voth Moon rings are named after the valiant Captain of the UEV (Unified Earth Vessel) Petra Gowanofski. Captain Courtney Viola Voth kept her spacecraft from slamming into the moon as her crew fought off unknown assailants trying to take over the ship. The U.E.V. Petra Gowanofski scraped by the moon's surface with barely a few meters to spare! With every available thruster at full blast, the ship gouged out a rift kilometers long. The gouge made by the spacecraft across the moon’s face can be seen clearly from Earth. After the Saturn Expedition ended, it was officially named Petra's Rift.

They, say this is how it happened.