Moon is Battered, Reveals New Gravity Map

    December 5, 2012
    Sean Patterson
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A new gravity map of Earth’s moon shows a record of billions of years of impacts on its surface. The new map, generated by NASA‘s Gravity Recovery and Interior Laboratory (GRAIL) mission, is now the highest resolution gravity field map of any celestial body. It will allow scientists to learn about the internal structure of the moon, its tectonic structures, volcanic landforms, basin rings, crater central peaks, and craters.

“What this map tells us is that more than any other celestial body we know of, the moon wears its gravity field on its sleeve,” said Maria Zuber, GRAIL Principal Investigator at the Massachusetts Institute of Technology (MIT). “When we see a notable change in the gravity field, we can sync up this change with surface topography features such as craters, rilles or mountains.”

The gravity map was created from data taken by two washing machine-sized spacecraft (GRAIL-A and GRAIL-B, or “Ebb” and “Flow”) orbiting the moon. The probes transmit radio signals to each other to precisely measure the distance between them while orbiting the moon. As they pass over areas of greater or lesser gravity on the moon, the distance between them shifts slightly.

The probes also revealed that the bulk density of the moon’s highland crust is “substantially” lower than predicted. The density is, however, consistent with data from the Apollo missions in the 70s. This suggests that samples of the moon brought back by astronauts are a good representation of processes on the moon. The bulk composition of the moon is also similar to that of Earth, providing evidence for models that show the moon was formed from a giant impact with Earth in the early solar system.

“We used gradients of the gravity field in order to highlight smaller and narrower structures than could be seen in previous datasets,” said Jeff Andrews-Hanna, a GRAIL scientist at the Colorado School of Mines. “This data revealed a population of long, linear gravity anomalies, with lengths of hundreds of kilometers, crisscrossing the surface. These linear gravity anomalies indicate the presence of dikes, or long, thin, vertical bodies of solidified magma in the subsurface. The dikes are among the oldest features on the moon, and understanding them will tell us about its early history.”

(Image courtesy NASA/JPL-Caltech/MIT/GSFC)

  • Darryl

    Let me get this right. We slam a nuclar weapon into the moon 6 months or more ago and new findings state that the moon was beat up before from astoroids? Wow! I think the Profs are missing something here! WHAT IS THE HALF LIFE OF YOUR EXPLOSION? Duh the radiation readings your thermal readings in zero gravity … Hey and these are the people of science. They should study common sense.

    • Amalasan

      There was no nuclear explosion on the moon, what are you high??
      Also do you not understand how the gravity map was made?
      It was made by recording micoshifts in orbiting satellites around the moon.
      And as well any fallout radiation would be so miniscule compared to be the normal background solar radiation and have no effect on this recording process.
      You should learn more of BASIC science

      • carl

        OMG!!! WE SET OFF ALL THESE NUCLEAR BOMBS ON THE MOON. What has the moon ever done to us

  • rolf

    well, what w/ all dem nazis on de dark side, what do we expect? flowers?

  • Jim in Boulder

    This short video was neat but a great comparison would have been a side by side surface view. The CSM conclusion about igneous dikes would have been nice to discern if they are radial or ring dikes.

  • http://yahoo.com m

    You can tell wich side of the moon is facing the planet earth and why the moon does not rotate. Very impressive!

    • Amalasan

      Sigh, the moon does rotate. It rotates at same rate as it’s orbit.
      As to why it does this, its a process called tidal drag. The moon’s effect on the oceans shifts energy from the earth’s rotation into the moon’s velocity. When the moon as formed the earth had a 12 hour day and the moon’s orbit was much lower (making look twice as big from the perspective on the earth’s surface). This tidal drag process is still ongoing and on day, millions of years in the future, the earth will be in geosynchronous orbit around the earth while appearing half as small (from a orbit much farther out). Half the world at that time will never see the moon.

  • Ed

    Well I’ll tell what the Moon did to us to deserve the thousand nuclear bombs we blew up on the surface not to mention the ones we detonated two miles under ground. That’s what made the craters on the moon. Anyway I had my Jeep at the beach and it got stuck in the sand. Then the Moon moved around the earth and the Moons gravity sucked the ocean up on top of my Jeep. that why it was a good idea to nuke the moon. That will teach it a lesson or two.