Rock from Earth, found on Moon?


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The uncertainty of science: Scientists studying rocks brought back by the Apollo 14 lunar mission have concluded that one sample originally came from the Earth, and if so would be the oldest known Earth rock.

It is possible that the sample is not of terrestrial origin, but instead crystallized on the Moon, however, that would require conditions never before inferred from lunar samples. It would require the sample to have formed at tremendous depths, in the lunar mantle, where very different rock compositions are anticipated. Therefore, the simplest interpretation is that the sample came from Earth.

The team’s analyses are providing additional details about the sample’s history. The rock crystallized about 20 kilometers beneath Earth’s surface 4.0-4.1 billion years ago. It was then excavated by one or more large impact events and launched into cis-lunar space. Previous work by the team showed that impacting asteroids at that time were producing craters thousands of kilometers in diameter on Earth, sufficiently large to bring material from those depths to the surface. Once the sample reached the lunar surface, it was affected by several other impact events, one of which partially melted it 3.9 billion years ago, and which probably buried it beneath the surface. The sample is therefore a relic of an intense period of bombardment that shaped the Solar System during the first billion years. After that period, the Moon was affected by smaller and less frequent impact events. The final impact event to affect this sample occurred about 26 million years ago, when an impacting asteroid hit the Moon, producing the small 340 meter-diameter Cone Crater, and excavating the sample back onto the lunar surface where astronauts collected it almost exactly 48 years ago (January 31–February 6, 1971).

The scientists also admit that their conclusion is controversial and will be disputed. If true, however, it suggests that there is significant material on the Moon from the early Earth that can provide a window into parts our planet’s history that are presently inaccessible.

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2 comments

  • Edward

    “The mystery of the cat,” or where did this rock come from?
    https://www.youtube.com/watch?v=caQqMnueJps (7 minutes, From the series “From the Earth to the Moon”)
    There’s a story here, a story about what happened

    For the astronauts who picked up that rock, they looked for the unusual, the ones with the interesting story to tell. “[Context] and knowing which rocks to pick up in the first place is what might separate you from those little robots, you know, those ones some jaded souls think should have your job.

  • Royal Hiney

    Of course! It looks like somebody forgot to sort this one in the ” from the moon” bin and it would up in the “from the earth” bin and got treated with the results expected.

    I sometimes make mistakes like that when I sort merchandise at my job at Target too.

    It seems like the test results always depend on preconceptions in the shell game called science.

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