“If we want to study those early periods, we need to go someplace else to do it and the moon is the closest and the most accessible example,” Zuber said.

For Mars, the finding that a planet’s crust can be so deeply fractured has implications in the search for extraterrestrial life.

The fractures provide a pathway for water to move from inside the planet to the surface, and vice versa. Scientists believe Mars was once much warmer and wetter than the cold, dry desert it is today.

“If there ever were microbes on the surface that had to head away to a better environment, they could have gone very deep within the crust of Mars,” Zuber said.

The research is published in this week’s journal Science.