Sep 6, 2022 - Science

What the Moon can tell us about Earth

Illustration of the moon with a thought bubble made from Earth

Illustration: Annelise Capossela/Axios

The Moon is a time capsule that could provide key information about Earth's ancient history.

Why it matters: Understanding the early history of our planet and our Moon could help scientists figure out more about how the planets formed and even how life eventually took hold on our world.

  • "When you look at the Moon, you're looking at not just a neighbor in space, but kind of an extension of the Earth," NASA Moon scientist Noah Petro tells Axios.
  • "I like to kind of glibly think of the Moon as the eighth continent of the Earth."

The big picture: As NASA aims to send astronauts back to the Moon for the first time since Apollo as part of its Artemis program, scientific attention is now turning to the Moon, with researchers hopeful that some of their outstanding questions will be answered.

  • Instead of visiting just a few landing sites once like the Apollo missions, Artemis aims to create a sustainable presence on the Moon.
  • That would allow researchers to gain a deep understanding of that part of the lunar surface and potentially stage missions to other areas.
  • "Part of the area where the Artemis missions will be exploring is on the rim of this enormous basin," Petro added. "We don't know how old it is. So for me, understanding the age of that crater becomes a very important point in the history of the Earth and the Moon's history in its formation."

How it works: The movement of Earth's tectonic plates constantly churns away craters and older crust, effectively hiding geological evidence of our planet's ancient past.

  • But the Moon — widely believed to have formed after a collision between Earth and a rocky body called Theia — is a record of that history.
  • Because the Earth and the Moon occupy the same part of space, the craters — formed from collisions — seen on the Moon are likely representative of the same kinds of activity that happened on our planet as well
  • Studying those craters could allow researchers to piece together just what was happening in space millions — if not billions — of years ago, possibly giving them clues about how life arose, how water was delivered to our planet, and how the Earth's crust, mantle and core evolved.
  • Earth's "early record is lost, and we think it may have been really critical to when life was able to form on Earth," planetary geologist Brett Denevi, of Johns Hopkins University Applied Physics Laboratory, tells Axios. "It shapes that habitable environment and really affects it."

Background: Analysis of Moon rocks brought back to Earth during the Apollo program has allowed scientists to get a good idea of how old certain parts of the Moon are and its composition.

  • But those missions only went to a limited number of landing sites in the equatorial region, leaving scientists with more questions to answer.
  • And more recent robotic missions have uncovered other lunar mysteries.
  • "We went to these really wonderful locations," Petro said. "All of the six landing sites are really amazing. But we never went back."
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