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Puzzle: Why are new moon craters appearing faster than expected?

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File:GRAIL's gravity map of the moon.jpg
gravity map of Moon/NASA

From Charles Q. Choi at Space.com:

New craters are forming on the surface of the moon more frequently than scientists had predicted, a new study has found. The discovery raises concerns about future moon missions, which may face an increased risk of being hit by falling space rocks.

The moon is dotted with a vast number of craters, some billions of years old. Because the moon has no atmosphere, falling space rocks don’t burn up like they do on Earth, which leaves the moon’s surface vulnerable to a constant stream of cosmic impacts that gradually churn the top layer of material on its surface. You can see a before-and-after video of a new moon crater here.More.

From New Scientist:

The revised number of craters suggests the moon is pummeled by space rocks much more frequently than predicted, says Kathleen Mandt of the Southwest Research Institute in San Antonio, Texas. It also suggests that the soil on the lunar surface is turning over so often that materials like water molecules could escape into space sooner than previously thought. That could have important implications for researchers trying to date rocks on the moon, or future initiatives hoping to mine resources out of the moon.

“I like it when theories are proven wrong, or exciting new things come up,” she says. “The Lunar Reconnaissance Orbiter is starting to show there’s a lot we don’t know about the moon.” More.

We don’t know nearly as much as we should about our own solar system; better to be cautious about great claims about the universe.

See also: Two models of planet formation duking it out

Note: Paper at Nature. ((paywall))

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3 Replies to “Puzzle: Why are new moon craters appearing faster than expected?

  1. 1
    aarceng says:

    How does that affect estimates of the age of the moon based on the number of craters?

  2. 2
    Vy says:

    How does that affect estimates of the age of the moon based on the number of craters?

    That was done years ago with previous studies showing the mental gymnastics that went into inferring planetary ages from crater counts.

    This study just dumps a few more nails into that coffin.
    From Crev.info:

    Space.com says of the “Impact!” of the finding, “New Moon Craters Are Appearing Faster Than Thought.” Part of the new estimate comes from crater counts by LRO, including a whopping 222 new craters appearing just in the last 7 years, says Alexandra Witze in Nature. The other part comes from estimates of secondary craters formed from each new impact.

    The scientists also found broad zones around these new craters that they interpreted as the remains of jets of debris following impacts. They estimated this secondary cratering process is churning the top 0.8 inches (2 centimeters) of lunar dirt, or regolith, across the entire lunar surface more than 100 times faster than thought.

  3. 3
    tjguy says:

    Aarceng @1 How does this affect the age of the moon?

    Well, it just got 100-fold younger!

    New study of craters shows that moon’s surface gets churned every 81,000 years, not every million years.

    http://crev.info/2016/10/moon-younger/

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