More than 50 years after the last manned moon mission, the Apollo program is still making groundbreaking discoveries.

Lunar rock collected by Apollo 17 is revealing more about the Light Mantle, a distinctive bright streak across the moon’s surface. It’s believed to be the remains of an ancient landslide that happened in the distant past, but the exact cause is unknown.

Asteroid strikes, debris from a nearby mountain and seismic activity are all possibilities, but orbital photographs can only reveal so much. Scientists are now studying a rock core from Apollo 17 that was recently unsealed for the first time in 50 years, allowing new insights into the geology of the area.