An ancient rock believed to be one of the Earth's oldest was found by astronauts on the moon and brought it back to our planet.
A new study suggests a chunk of material brought back by astronauts from the moon contains a tiny piece of Earth, which likely blasted off our planet during a powerful impact that occurred about 4 billion years ago.
David Kring, from Universities Space Research Association (USRA) at the Lunar and Planetary Institute in Houston, and colleagues analyzed lunar samples collected during the February 1971 Apollo 14 mission.
They found lunar sample 14321, also known as Big Bertha, is embedded with a rock fragment made of quartz, feldspar, and zircon. These materials rarely occur on the moon but are common here on Earth.
Chemical analyses showed the fragment crystallized in an oxidized environment at temperatures consistent with those near the subsurface of young Earth.
The evidence suggests the rock crystallized below Earth's surface between 4 billion and 4.1 billion years ago, during the Hadean Eon, when the fledgling Earth was regularly struck by large objects.
Asteroid Strike On Earth Brough Debris To The Moon
The researchers think the fragment reached the moon after a comet or asteroid hit Earth, sending debris into space. At the time, the moon was about three times closer to our planet than it is today.
The fragment endured further trauma on the moon's surface. Researchers said it was partially melted and possibly buried by another impact about 3.9 billion years ago.
It was excavated yet again by another collision 26 million years ago. This same impact created the Cone Crater that astronauts Alan Shepard and Edgar Mitchell explored and sampled during their moon mission nearly half a decade ago.
"It is an extraordinary find that helps paint a better picture of early Earth and the bombardment that modified our planet during the dawn of life," Kring said.
The findings were published in the journal Earth and Planetary Science Letters on Jan. 24.