WASHINGTON Tiny green and orange glass balls
brought back from the moon nearly 40 years ago by astronauts
show evidence that water existed there from the very beginning,
scientists reported on Wednesday.
They used a new method of analyzing elements in the lunar
sand samples to show strong evidence of water, dating back 3
Their study, published in the journal Nature, could support
evidence that water persists in shadowed craters on the moon's
surface -- and that the water could be native to the moon and
not carried there by comets.
Most scientists believe the moon was formed when a
Mars-size body collided with Earth 4.5 billion years ago.
The giant impact would have melted both proto-planets and
sent molten debris into orbit around the Earth.
Some of this would have eventually coalesced into the moon,
but the heat of the impact would have vaporized light elements
such as the hydrogen and oxygen needed to make water --
Erik Hauri of the Carnegie Institution for Science in
Washington had developed a technique called secondary ion mass
spectrometry or SIMS, which could detect minute amounts of
elements in samples. His team was using it to find evidence of
water in the Earth's molten mantle.
"Then one day I said, 'Look, why don't we go and try it on
the moon glass?"' Alberto Saal of Brown University, who helped
lead the study, said in a telephone interview.
"It took us three years to convince NASA to fund us."
The space agency was also loath to part with any of the
precious samples brought back by astronauts during the Apollo
missions in the 1970s.
Saal, Hauri and colleagues were able to get about 40 of the
little glass beads and break them apart for analysis.
What they found overturned the conventional wisdom that the
moon is dry.
"For 40 years people have tried (to find evidence of water)
and were not successful," Saal said.
"Common sense tell us there is nothing."
Saal's team did not find water directly, but they did
measure hydrogen, and it resembled the measurements they have
done to detect hydrogen, and eventually water, in samples from
The evidence shows that the hydrogen in the sample
vaporized during volcanic activity that would be similar to
lava spurts seen on Earth today.
"We looked at many factors over a wide range of cooling
rates that would affect all the volatiles simultaneously and
came up with the right mix," said James Van Orman, a former
Carnegie researcher now at Case Western Reserve University.
"It suggests the intriguing possibility that the moon's
interior might have had as much water as the Earth's upper
mantle," Hauri said in a statement.
"But even more intriguing -- if the moon's volcanoes
released 95 percent of their water, where did all that water
Some might still remain at the poles, frozen in the shadows
of craters, he speculated. Several lunar missions have found
just such evidence.
"If parts of the lunar mantle contain as much water as
Earth's, does this imply that the water has a common origin?"
Marc Chaussidon of the Centre de Recherches Petrographiques et
Geochimiques in Vandoeuvre-les-Nancy, France, asked in a
commentary in Nature.
More analysis might answer that question.
"We will pressure NASA for more samples," Saal said.
(Editing by Jackie Frank)