The researchers from Baylor used various sets of data collected from space crafts that measure the gravity around the moon, and compared them to maps and imaging of the moon’s surface. As a result, they found a dense metallic mass pulling down on the floor of the basin.
So, what is it? James and his team surmise it could be metal embedded in the moon’s mantle from the asteroid impact that caused the crater some estimated 4 billion years ago. If that’s true, it could be a time machine — and a gold mine — for scientists studying the history of the universe. All of that metal, and basically the entire area surrounding the mass and the crater, could tell them a lot about how the asteroid impact happened and what the solar system was like when it did.
“[The basin is] one of the best natural laboratories for studying catastrophic impact events, an ancient process that shaped all of the rocky planets and moons we see today,” James said.
Unfortunately the crater — and the mysterious substance below — aren’t visible to mere Earthbound humans, since they’re on, literally, the far side of the moon.