Cone Crater This is Cone Crater, a 370-meter diameter impact crater in the Fra Mauro Formation on the Moon. On February 6, 1971, Apollo 12 astronauts Alan Shepard and Edgar Mitchell retrieved rock samples from near the rim of this crater for study back on Earth.
In 2018, a team of researchers led by Jeremy Bellucci of the Swedish Museum of Natural History and including David Kring of the Center for Lunar Science and Exploration (part of NASA’s Solar System Exploration Research Virtual Institute) was conducting a detailed study of Apollo 14 rock samples and discovered something remarkable. Among the samples was a piece of rock that stood out. Analysis of the rock’s composition, enriched in quartz, feldspar and zircon, seemed to indicate that it originated not on the Moon, but formed between 4 and 4.1 billion years ago, about 12.4 miles below Earth’s surface. At that time, the young Earth, only about a half billion years old, was being repeatedly bombarded by great asteroid impacts. One or more of these impacts apparently excavated the rock, brought it to Earth’s surface, and then blasted it into space to land on the surface of the Moon. There, about 3.9 billion years ago, subsequent impacts seem to have partially melted the rock, fused it to surrounding lunar rock, and buried it beneath the lunar surface.
Then, 26 million years ago, another asteroid impact blasted the Moon forming Cone Crater, bringing the rock back to the Moon’s surface. There it lay until 1971 when it was picked up by the crew of Apollo 14 and returned to Earth.
It’s an amazing story. But even more amazing may be what this rock preserved on the Moon could tell us about our home world. The calculated age of this rock is older than any rock that has been found on Earth, where erosion and plate tectonics destroy records of the past. A preserved piece of the very young Earth could be one of the greatest treasures that has yet been returned from the Moon.