SETI NYT NEWS - Apollo Showed Luna's Violent Birth

Larry Klaes (
Wed, 21 Jul 1999 10:05:33 -0400

>Date: Tue, 20 Jul 1999 21:24:06 -0400
>Organization: SkyViews Astronomy & Space information Web Site
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>Subject: NEWS apollo
>Illustration by William K. Hartmann [attachments removed]
>NASA Buzz Aldrin on the lunar surface, July 20, 1969
>NASA The astronaut Buzz Aldrin, with a package of seismic
> instruments that were deployed on the Moon during the
> three-manby Apollo 11 mission in July 1969.
> July 20, 1999
> Apollo Opened Window on Moon's Violent Birth
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> Join a Discussion on Science in the News
> The Learning Network
> On This Day: July 20, 1969
> Science was low on the agenda when two Americans landed on
the Moon 30
> years ago today, beating the Russians in one of the cold
war's most costly
> and daring contests. But in time, the six lunar landings
from 1969 to 1972, in
> which a dozen people roamed another world for the first time,
probing its
> composition and taking hundreds of rocky samples, led to a
major surprise.
> For centuries scientists had assumed that
> the forces of nature were generally
> uniform, that comets and mountains, cats
> and molecules, all obeyed laws rooted in
> steadfastness. Newton and his intellectual
> heirs often saw the universe as a vast
> clockwork in which precise gears turned
> with slow deliberateness.
> But the 842 pounds of Moon rocks that the
> Apollo astronauts painstakingly gathered
> and brought back to Earth told a different
> story.
> Unforeseen clues led scientists to
> conclude that the Moon was born in
> cataclysm and searing heat. In time,
> evidence of similar violence was seen in
> relation to Mercury, Venus, Mars and
> other worlds that were oddly built, off kilter
> or spinning fast. Routine fury from the
> heavens, scientists eventually argued, had
> even altered life on Earth, periodically
> wiping out families of plants and animals, including the
> In hindsight, scientists and historians now say that the lunar
landings helped
> reveal the secret of cosmic violence, opening a line of
inquiry still advancing
> today.
> "We've learned that big impacts were an important part of
planetary formation,"
> said Dr. David Morrison, head of the space directorate at the
Ames Research
> Center of the National Aeronautics and Space Administration.
"Almost every
> planet shows a major anomaly."
> Apollo evidence of a violent lunar birth, said Dr. Stephen G.
Brush, a science
> historian at the University of Maryland, who has written about
the episode in
> "Fruitful Encounters" (Cambridge University Press, 1996),
"caused people to
> suddenly start thinking about ideas that were out of bounds
> "There was a general change in thinking about catastrophic
events," he said.
> Throughout history, leaders of science
> tended to hunt for uniformity in nature and to
> abhor chance events.
> As Einstein put it, "God does not play dice."
> For instance, the founders of paleontology
> saw periodic mass extinctions of ancient life
> as rooted in natural forces acting over
> millions of years. Their rivals, the
> catastrophists, inspired by religion, laid the
> die-offs to supernatural upheavals like Noah's
> flood.
> So too, planetary scientists. Working from
> assumptions of uniformity, they envisioned
> the Sun and its family of worlds as forming
> slowly over eons.
> When Dr. Immanuel Velikovsky argued
> otherwise in his 1950 book, "Worlds in
> Collision," taking biblical and archeological
> evidence to wild extremes, scientists battled
> him in print and threatened to stop buying
> textbooks from Macmillan, his publisher.
> Macmillan quickly sold the book's rights to
> Doubleday, which found it had acquired a
> best seller.
> Before the Apollo landings, scientists backed
> three rival theories of lunar origin. All were
> rooted in uniformitarianism, as the idea was
> known. And all had nicknames -- the sister,
> the daughter and the pickup theories.
> Sister had the Moon and Earth evolving
> separately from primordial rubble but in the
> same general neighborhood, as siblings. The
> daughter theory had the early Moon spinning
> off from Earth by fission, leaving the Pacific
> basin as a scar. Pickup saw the Moon as a
> small wandering planet that Earth's gravity
> had captured.
> The theorizing began to unravel on July 20,
> 1969, when Neil Armstrong and Buzz Aldrin
> landed on the Moon.
> "It looks like a collection," Col. Aldrin radioed
> back to Earth. The moonscape showed "just
> about every shape, angularity, granularity -- about every
variety of rock you could
> find."
> Hundreds of small craters and outcroppings lay before the
astronauts. In bulky
> spacesuits, they probed the site for 2 hours 21 minutes, at
the end hammering
> coring tubes through dusty soil to capture deeper rock. The
next day, July 21, the
> explorers blasted off for home, bringing back samples that
scientists handled like
> priceless jewels.
> The Moon rocks were full of surprises. Experts found that the
samples had little
> iron, water or other elements common on Earth, like sodium,
potassium and sulfur.
> That finding diminished the sister theory, because no
scientist could see how
> such stark differences might arise.
> Yet the inquiries also found that the Moon and Earth were
similar in terms of their
> mixes of oxygen isotopes, or light and heavy oxygen atoms.
That virtually ruled
> out the pickup theory, because studies of meteorites had shown
> extraterrestrial objects tended to have unique isotopic
> The daughter theory died on its own without the aid of the
Apollo findings.
> Studies of planetary dynamics showed that Earth could never
have spun fast
> enough to give birth.
> As the mystery of the Moon's
> origin deepened, scientists were
> not only confused and frustrated,
> but dwindling in number as Apollo
> money in the early 1970's dried up.
> Still, a few persisted.
> Dr. William K. Hartmann was a
> young astronomer who in the
> 1960's at the University of Arizona
> had peered through telescopes to
> scrutinize the pockmarked Moon.
> Like other scientists, he joined the
> debate over whether the origin of
> the craters was slow and volcanic
> or quick and violent.
> The Apollo program settled the issue in favor of meteorite
crashes, as Dr.
> Hartmann had suspected. The astronauts found that the craters
bore no signs of
> flowing lava and much evidence of great impact forces that had
welded soil and
> rubble into solid rock.
> In 1972, as the Apollo landings ended, Dr. Hartmann was
inspired to extend his
> impact reasoning after reading the translation of a book by a
Soviet scientist,
> Victor S. Safronov. He had speculated that cosmic dust and
rubble spinning
> around the primordial Sun had repeatedly collided and melded
together, forming
> ever larger aggregations, like swarms of asteroids, from which
the planets
> eventually arose.
> Dr. Hartmann went further. Working at the Planetary Science
Institute in Tucson,
> Ariz., with Dr. Donald R. Davis, he reasoned that even larger
bodies had formed,
> perhaps dozens of them.
> One of these might have begot the Moon, Dr. Hartmann and Dr.
Davis found in
> their analyses. Some four and a half billion years ago, they
theorized, the speeding
> wanderer collided with the early Earth and shattered to
smithereens. The
> planetoid's heavy iron core burrowed into the Earth. Its light
crustal remains, as
> well as bits of Earth's crust, were blown into space and then
formed an orbiting
> ring of debris, from which the Moon in turn coalesced.
> The searing heat of such a collision, the Tucson scientists
reasoned, could explain
> why the Moon held no water and few volatile elements. All had
boiled away. And
> the Moon's relative lack of iron was explained by the lost core.
> In 1974, at a meeting at Cornell University, Dr. Hartmann
presented the radical idea
> publicly for the first time. He was nervous. Afterward, a hand
in the audience went
> up. It was Dr. Alastair G. W. Cameron, a top astrophysicist at
Harvard, a man some
> young scientists greatly admired.
> The junior scientist braced for
> the worst, ready for a blast of
> criticism. "I was quaking in my
> boots," Dr. Hartmann recalled.
> Instead, Dr. Cameron agreed,
> saying that he and a young
> colleague, Dr. William R. Ward,
> had arrived at similar
> conclusions by a different route.
> Moreover, the intruder, Dr.
> Cameron and Dr. Ward had
> calculated, was even bigger than
> the Tucson team had
> envisioned.
> "I said it was at least as big as Mars," Dr. Cameron recalled.
So in theory at least,
> the hypothetical impactor was a blockbuster about half the
diameter of Earth.
> Greatly encouraged, Dr. Hartmann, who paints in his spare
time, began illustrating
> the great-impact idea. Eventually, his colorful visualizations
appeared in many
> science publications, including one reproduction on the cover
of Science Times.
> Despite agreement among the four experts, most scientists at
first ignored or
> disparaged the great-impact idea. It was too radical, too much
like the discredited
> catastrophism of Velikovsky.
> But slowly it caught on, especially as computer simulations of
that distant era of
> rocky creation showed that the collision idea was not crazy.
> In 1984, a dozen years after the last Apollo mission, a
conference was held to
> discuss the Moon's origins. To attract wide participation, it
was held in Hawaii,
> scientists liking paradise as much as anybody else. A hundred
or so planetary
> specialists showed up.
> Surprisingly, a strong consensus emerged that the radical
theory was probably
> right.
> "The conference was incredible," Don E. Wilhelms, a lunar
geologist at the United
> States Geological Survey, recalled in his book, "To a Rocky
Moon" (University of
> Arizona Press, 1993). Beaches and gentle breezes were ignored
as meeting
> participants grew increasingly excited over the idea that "our
satellite is a daughter
> of not one but two parents."
> Dr. George W. Wetherill of the Carnegie Institution of
Washington told meeting
> participants of his supportive calculations, which showed that
four and a half
> billion years ago perhaps 20 or so small planet-sized bodies
sped through the inner
> solar system, making a large impact quite likely.
> His work, Dr. Wetherill said in an
> interview, showed that sketchy
> ideas of planetary upheaval were
> "clearly correct."
> The watershed event encouraged
> scientists to look for signs of
> violence among other planets, and
> led to a flurry of papers. In time,
> cosmic tumult was tied to
> Mercury's lack of a thick crust, to
> Venus's spinning backward, to
> Mars' fast rotation and to Uranus'
> bizarre orientation. Most planets
> have an axis of rotation that is
> more or less perpendicular to the
> plane of the solar system. But the gas giant is tilted, its
axis listing at 97 degrees.
> Today, debate on the Moon's origin is still led by the
great-impact theory, with
> scientists continuing to probe its nuances. In 1997, Dr. Robin
M. Canup, a
> scientist at the University of Colorado at Boulder, working
with Dr. Cameron of
> Harvard, suggested the impactor's mass might have been as
large as three times
> that of Mars.
> In an interview, Dr. Canup, who now works at the Southwest
Research Institute in
> Boulder, said her newest computer models show not only that
large impacts "were
> ubiquitous" in the early days of the solar system but that
moon-forming smashups
> were common. Few of these ancient moons survived, she added,
because most
> were in unstable orbits.
> Skeptics remain, especially among geochemists. Many find
insufficient chemical
> evidence to convince them of the cataclysm. Some would like to
find chemical
> clues of blistering heats on Earth.
> "Although a general picture may be emerging, many issues
remain hotly debated,"
> Dr. Alex N. Halliday, an Earth scientist in Switzerland, and
Dr. Michael J. Drake, a
> planetary scientist at the University of Arizona, wrote in the
March 19 issue of the
> journal Science.
> But suggestive new clues are also emerging. NASA's Lunar
Prospector spacecraft,
> which cost $63 million and arrived in lunar orbit last year,
recently confirmed that
> the Moon has a very small core, bolstering the giant-impact
> "This is a critical finding," said Dr. Alan Binder of the
Lunar Research Institute in
> Tucson, the lead investigator for Lunar Prospector.
> The spacecraft found that the lunar core holds less than 4
percent of the Moon's
> total mass, and probably 2 percent or less. In contrast, the
Earth's iron core is
> about 30 percent of the planetary mass. Dr. Binder said
further analysis of Lunar
> Prospector data might help "pin down for good" whether the
giant-impact model is
> right.
> Dr. Hartmann of the Planetary Science Institute in Tucson, who
helped get the ball
> rolling and is now 60, said he hoped astronauts one day
returned to the Moon,
> greatly expanding the number of rocky samples and perhaps
aiding the idea of the
> colossal smashup.
> "I'm always interested in new data," he said. "There are many
places you might
> look."
> Related Sites
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The Times has no control over their
> content or availability.
> The Origin of the Moon.
> NASA: Apollo 11.
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