January 27, 2012 | David F. Coppedge

Lunar Upsets Challenge Paradigms

Forty years after the last moonwalkers came home, new discoveries about the moon are calling into question what scientists know about our celestial partner.  But is it legitimate for scientists to invoke mystery forces when a favored theory faces falsifying evidence?

Shocking physics:  Looking into the crystal balls Apollo astronauts brought back from the moon, namely zircon minerals, geologists at Curtin University decided their data “challenges” the “current paradigm” known as the Late Heavy Bombardment (see 1/09/2012).  PhysOrg reported about “impact-related shock features in lunar zircon, giving scientists a new conceptual framework to explain the history and timing of meteorite impact events in our solar system.”  When a “new conceptual framework” challenges a “current paradigm,” the ripple effects can undermine textbooks and other related theories.  Since theories about the “timing of meteorite impact events” are built on lunar data, this puts theories of the entire history of the solar system at risk.

Alternative energy source:  The moon had a long-lasting dynamo.  That statement should floor you if you are a typical planetary scientist.  To see why, read on Space.com why physicists are scrambling to find alternative power, like homeowners frantically searching for a backup generator when the lights just went out.  The data come from crystals in basalt sample #10020 from the moon that, according to the evolutionary view of radiometric dating, is 3.7 billion years old – yet has remnant magnetism.  In their dating scheme, that’s almost a billion years after the formation of the moon.  Any primeval dynamo that could have magnetized the rock should have been long gone by then.  PhysOrg put the surprise in the first sentence: “The moon has this protracted history that’s surprising.  This provides evidence of a fundamentally new way of making a magnetic field in a planet a new power source [sic].”

That quote was from Benjamin Weiss, an associate professor of planetary science at MIT, one of the authors of a paper in Science (27 January 2012: Vol. 335 no. 6067 pp. 453-456, doi: 10.1126/science.1215359).  “Such a long-lived lunar dynamo probably required a power source other than thermochemical convection from secular cooling of the lunar interior,” they wrote, referring to the consensus dynamo theory.  “The inferred strong intensity of the lunar paleofield presents a challenge to current dynamo theory.”  What powered it?  “an alternative energy source,” they suggested.  Have they found one?  No.  They tossed out a couple of possibilities at the end of the paper: maybe stirring from precession did it.  Maybe a big meteor walloped the interior into a temporary molten stir.  It hardly seems they considered those options seriously when they ended, “the late, intense paleomagnetic record from 10020 presents a challenge to current dynamo theory.”

Ray tracing algorithm:  This story’s not from our moon, but from the asteroid Vesta, where the DAWN spacecraft is undertaking an orbital reconnaissance.  A new photograph displayed on PhysOrg shows a crater with both dark and light rays.  “There is dark and bright material located across Vesta,” the article said, “but it is unusual to have a crater with both bright and dark ejecta rays.”  Although the press release didn’t say so, the darkness of crater rays is usually taken as an indicator of age.  Looking at our moon, planetary scientists assume that crater rays begin bright and darken over time due to “space weathering,” the effect of solar wind particles on lunar dust.  (See, for instance, in the “Geology of the Moon” article on Ask.com, which states: “The impact process excavates high albedo materials that initially gives the crater, ejecta, and ray system a bright appearance. The process of space weathering gradually decreases the albedo of this material such that the rays fade with time.”)  The new Vesta combo crater shows that dark and light rays can originate from the same impact, potentially undermining the ray-dating algorithm.

Which moon?  We may not be able to talk about “the moon” in our nighttime sky.  New Scientist just announced that “Hundreds of tiny moons may be orbiting Earth.”  The idea is that wandering asteroids may get captured in Earth orbit from time to time.  The Earth sits in a gravity well, after all, so it’s not surprising that it would pull objects into its tractor beam.  “They orbit at distances between five and 10 times as far from Earth as the moon,” the article said.  “Most stay in orbit less than a year, although some stay much longer. One object in the team’s simulations stayed in orbit for almost 900 years.”  This could provide some water cooler conversation.  When someone talks about “the moon,” you might respond, “To which moon are you referring?”  They’ll think you are Looney Tunes till you explain.  You can even quote Shakespeare; “There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy.”

Blue marble:  We end with a breathtaking finale.  The historic Apollo 8 mission in 1968 provided the first human-photographed image of the Earth from a distance.  Subsequent spacecraft have improved on “Earth from space” views over the years.  Now, an Earth-observing spacecraft launched in October, dubbed Suomi NPP, has just released a stunner – a realistic photograph of our “Blue Marble” from 512 miles that is so clear, so beautiful, it deserves to be set to music.  At Space.com you can download it for a screen save in several sizes.  At the Suomi NPP website, you can download the complete highest-resolution image (16.4 mb, 8000 x 8000 pixels) and soar over North and Central America with incredible detail (for starters, check out Lake Mead, Grand Canyon and Lake Powell).  Because the spacecraft flies in a sun-synchronous orbit (see Suomi NPP feature), we can expect more fully-lit images of other faces of our planet as Earth rotates underneath.

Look at the Blue Marble photograph and ponder it awhile.  Think about the proud little creatures running around down there who pretend they can understand the cosmos.

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