[meteorite-list] NASA solves half-century old moon mystery

From: J. <J._at_meteoritecentral.com>
Date: Thu Apr 22 10:18:29 2004
Message-ID: <007901c2db64$b3b96740$4e8328d1_at_yourus67pi6luv>

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http://www.spaceflightnow.com/news/n0302/22moon/

In the early morning hours of Nov. 15, 1953, an amateur astronomer in =
Oklahoma photographed what he believed to be a massive, white-hot =
fireball of vaporized rock rising from the center of the moon's face. If =
his theory was right, Dr. Leon Stuart would be the first and only human =
in history to witness and document the impact of an asteroid-sized body =
impacting the moon's scarred exterior.=20



Almost a half-century, numerous space probes and six manned lunar =
landings later, what had become known in astronomy circles, as "Stuart's =
Event" was still an unproven, controversial theory. Skeptics dismissed =
Stuart's data as inconclusive and claimed the flash was a result of a =
meteorite entering Earth's atmosphere. That is, until Dr. Bonnie J. =
Buratti, a scientist at NASA's Jet Propulsion Laboratory (JPL) in =
Pasadena, and Lane Johnson of Pomona College, Claremont, Calif., took a =
fresh look at the 50-year- old lunar mystery.=20

"Stuart's remarkable photograph of the collision gave us an excellent =
starting point in our search," said Buratti. "We were able to estimate =
the energy produced by the collision. But we calculated that any crater =
resulting from the collision would have been too small to be seen by =
even the best Earth-based telescopes, so we looked elsewhere for proof." =


Buratti and Lane's reconnaissance of the 35-kilometer (21.75- mile) wide =
region where the impact likely occurred led them to observations made by =
spacecraft orbiting the moon. First, they dusted off photographs taken =
from the Lunar Orbiter spacecraft back in 1967, but none of the craters =
appeared a likely candidate. Then they consulted the more detailed =
imagery taken from the Clementine spacecraft in 1994.=20

"Using Stuart's photograph of the lunar flash, we estimated the object =
that hit the moon was approximately 20 meters (65.6 feet) across, and =
the resulting crater would be in the range of one to two kilometers (.62 =
to 1.24 miles) across. We were looking for fresh craters with a =
non-eroded appearance," Buratti said.=20

Part of what makes a moon crater look "fresh" is the appearance of a =
bluish tinge to the surface. This bluish tinge indicates lunar soil that =
is relatively untouched by a process called "space weathering," which =
reddens the soil. Another indicator of a fresh crater is that it =
reflects distinctly more light than the surrounding area.=20

Buratti and Lane's search of images from the Clementine mission revealed =
a 1.5-kilometer (0.93 mile) wide crater. It had a bright blue, =
fresh-appearing layer of material surrounding the impact site, and it =
was located in the middle of Stuart's photograph of the 1953 flash. The =
crater's size is consistent with the energy produced by the observed =
flash; it has the right color and reflectance, and it is the right =
shape.=20

Having the vital statistics of Stuart's crater, Buratti and Lane =
calculated the energy released at impact was about .5 megatons (35 times =
more powerful than the Hiroshima atomic bomb). They estimate such events =
occur on the lunar surface once every half-century.=20

"To me this is the celestial equivalent of observing a once- =
in-a-century hurricane," observed Buratti. "We're taught the moon is =
geologically dead, but this proves that it is not. Here we can actually =
see weather on the moon," she said.=20

While Dr. Stuart passed on in 1968, his son Jerry Stuart offered some =
thoughts about Buratti and Lane's findings. "Astronomy is all about =
investigation and discovery. It was my father's passion, and I know he =
would be quite pleased," he said.=20

Buratti and Lane's study appears in the latest issue of the space =
journal, Icarus.=20

The NASA Planetary Geology and Planetary Astronomy Programs and the =
National Science Foundation funded Buratti's work. The California =
Institute of Technology manages JPL for NASA.=20

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<DIV><FONT face=3DArial size=3D2><A=20
href=3D"http://www.spaceflightnow.com/news/n0302/22moon/">http://www.spac=
eflightnow.com/news/n0302/22moon/</A></FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT>&nbsp;</DIV>
<DIV>
<P>In the early morning hours of Nov. 15, 1953, an amateur astronomer in =

Oklahoma photographed what he believed to be a massive, white-hot =
fireball of=20
vaporized rock rising from the center of the moon's face. If his theory =
was=20
right, Dr. Leon Stuart would be the first and only human in history to =
witness=20
and document the impact of an asteroid-sized body impacting the moon's =
scarred=20
exterior. </P>
<P>&nbsp;</P>
<P>Almost a half-century, numerous space probes and six manned lunar =
landings=20
later, what had become known in astronomy circles, as "Stuart's Event" =
was still=20
an unproven, controversial theory. Skeptics dismissed Stuart's data as=20
inconclusive and claimed the flash was a result of a meteorite entering =
Earth's=20
atmosphere. That is, until Dr. Bonnie J. Buratti, a scientist at NASA's =
Jet=20
Propulsion Laboratory (JPL) in Pasadena, and Lane Johnson of Pomona =
College,=20
Claremont, Calif., took a fresh look at the 50-year- old lunar mystery. =
</P>
<P>"Stuart's remarkable photograph of the collision gave us an excellent =

starting point in our search," said Buratti. "We were able to estimate =
the=20
energy produced by the collision. But we calculated that any crater =
resulting=20
from the collision would have been too small to be seen by even the best =

Earth-based telescopes, so we looked elsewhere for proof."=20
<P>Buratti and Lane's reconnaissance of the 35-kilometer (21.75- mile) =
wide=20
region where the impact likely occurred led them to observations made by =

spacecraft orbiting the moon. First, they dusted off photographs taken =
from the=20
Lunar Orbiter spacecraft back in 1967, but none of the craters appeared =
a likely=20
candidate. Then they consulted the more detailed imagery taken from the=20
Clementine spacecraft in 1994.=20
<P>"Using Stuart's photograph of the lunar flash, we estimated the =
object that=20
hit the moon was approximately 20 meters (65.6 feet) across, and the =
resulting=20
crater would be in the range of one to two kilometers (.62 to 1.24 =
miles)=20
across. We were looking for fresh craters with a non-eroded appearance," =
Buratti=20
said.=20
<P>Part of what makes a moon crater look "fresh" is the appearance of a =
bluish=20
tinge to the surface. This bluish tinge indicates lunar soil that is =
relatively=20
untouched by a process called "space weathering," which reddens the =
soil.=20
Another indicator of a fresh crater is that it reflects distinctly more =
light=20
than the surrounding area.=20
<P>Buratti and Lane's search of images from the Clementine mission =
revealed a=20
1.5-kilometer (0.93 mile) wide crater. It had a bright blue, =
fresh-appearing=20
layer of material surrounding the impact site, and it was located in the =
middle=20
of Stuart's photograph of the 1953 flash. The crater's size is =
consistent with=20
the energy produced by the observed flash; it has the right color and=20
reflectance, and it is the right shape.=20
<P>Having the vital statistics of Stuart's crater, Buratti and Lane =
calculated=20
the energy released at impact was about .5 megatons (35 times more =
powerful than=20
the Hiroshima atomic bomb). They estimate such events occur on the lunar =
surface=20
once every half-century.=20
<P>"To me this is the celestial equivalent of observing a once- =
in-a-century=20
hurricane," observed Buratti. "We're taught the moon is geologically =
dead, but=20
this proves that it is not. Here we can actually see weather on the =
moon," she=20
said.=20
<P>While Dr. Stuart passed on in 1968, his son Jerry Stuart offered some =

thoughts about Buratti and Lane's findings. "Astronomy is all about=20
investigation and discovery. It was my father's passion, and I know he =
would be=20
quite pleased," he said.=20
<P>Buratti and Lane's study appears in the latest issue of the space =
journal,=20
Icarus.=20
<P>The NASA Planetary Geology and Planetary Astronomy Programs and the =
National=20
Science Foundation funded Buratti's work. The California Institute of =
Technology=20
manages JPL for NASA. <!--END BODY TEXT --></P></DIV></BODY></HTML>

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Received on Sun 23 Feb 2003 12:55:01 PM PST