Gravity maps of moon reveal deeply fractured crust

SAN FRANCISCO Wed Dec 5, 2012 7:23pm EST

A penumbral eclipse of the moon is seen in the night sky in Manila November 28, 2012. REUTERS/Romeo Ranoco

A penumbral eclipse of the moon is seen in the night sky in Manila November 28, 2012.

Credit: Reuters/Romeo Ranoco

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SAN FRANCISCO (Reuters) - Asteroids and comets colliding with the moon not only pitted its surface but also severely fractured its crust, researchers with NASA said on Wednesday, in a finding that could help crack a Martian puzzle.

On Mars, similar fracturing would have given water on the surface a way to penetrate deep in the ground, where it may remain today, they said.

"Mars might have had an ancient ocean and we're all wondering where it went. Well, that ocean could well be underground," planetary scientist Maria Zuber, with the Massachusetts Institute of Technology, told reporters at the American Geophysical Union conference in San Francisco.

The discovery that the moon's crust is deeply fractured came from a pair of small probes that comprise NASA's Gravity Recovery and Interior Laboratory, or GRAIL, mission. The identical spacecraft have been following each other around the moon for nearly a year.

Scientists have been monitoring the distance between the two, which changes slightly as they fly over denser regions of the moon.

The gravitational pull of the additional lunar mass causes first the leading probe and then the other one to speed up, altering the gap between them.

The data, assembled into the first detailed gravity maps of the moon, reveal that asteroids and comets cratered the surface and fractured the crust, possibly all the way down to the mantle.

"If you look at the surface of the moon and how heavily cratered it is, all terrestrial planets look that way, including the Earth," said Zuber, the lead GRAIL scientist.

Evidence of the phenomenon on Earth was wiped out by tectonic plate movements, erosion and other natural events.

"If we want to study those early periods, we need to go someplace else to do it and the moon is the closest and the most accessible example," Zuber said.

For Mars, the finding that a planet's crust can be so deeply fractured has implications in the search for extraterrestrial life.

The fractures provide a pathway for water to move from inside the planet to the surface, and vice versa. Scientists believe Mars was once much warmer and wetter than the cold, dry desert it is today.

"If there ever were microbes on the surface that had to head away to a better environment, they could have gone very deep within the crust of Mars," Zuber said.

The research is published in this week's journal Science.

(Editing by Tom Brown and Xavier Briand)

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Comments (5)
ccharles wrote:
Theres no serious evidence that the moon is pock marked by impact craters. How many times since we have been capable of viewing and recording have we seen a impact on the moon? none. There is some that look like impact, but there is alot more that do not. They are clean pock marks with no ejector pattern.

Dec 09, 2012 7:40pm EST  --  Report as abuse
OzBolts wrote:
Yes, but the time we have spent viewing and recording the moon is an incredibly insignificant amount of time in the universe. I know we humans like to think we are the be-all and end-all of creation and science… but the truth is our time within existence has been pitifully short. Though, you wouldn’t know that by our arrogance.

Dec 09, 2012 8:39pm EST  --  Report as abuse
amibovvered wrote:
Water on the surface or below clearly relies on the atmosphere that prevents water from evaporating into the cosmos. Life as we know it utterly depends on the the existence of the atmosphere, after all. The focus should be on that fact.

Dec 10, 2012 12:14am EST  --  Report as abuse
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