KT layer helium source

[WOlewiler@aol.com]

March 21, 2000 -- Scientists from the University of Hawaii and NASA have 
unearthed an unlikely collection of time capsules bearing extraterrestrial 
cargo from the distant past when an asteroid collided with Earth. What are 
these durable treasure chests from prehistory? Buckyballs -- tiny molecular 
cages made of 60 or more carbon atoms. 

"We discovered extraterrestrial gases trapped inside buckyballs in a one-inch 
thick sedimentary layer of clay that [formed from the fallout of an asteroid 
impact 65 million years ago]," said Ted Bunch, a scientist at NASA's Ames 
Research Center. The clay layer, known as the Cretaceous/Tertiary boundary, 
marks a period of extreme biological change including mass extinctions and 
the end of the dinosaurs. 
    Fullerenes -- better known as "buckyballs" -- are hollow, cage-like 
molecules made of carbon atoms. They are named in honor of Buckminster 
Fuller, designer of the geodesic dome that resembles the molecule. 
    Bunch and his colleagues, led by Luann Becker, a geochemist at the 
University of Hawaii, believe that the gas must have come from space because 
it contains helium rich in the isotope 3He.
    "Helium from different sources on Earth, like our atmosphere or the 
exhaust from volcanoes, has a ... different isotopic signature from the 
helium in a meteorite," said Becker. The nuclei of most helium atoms have two 
protons and two neutrons. This dominant isotope is called helium-4 (4He). A 
smaller fraction of helium atoms comes in the 3He variety with just one 
neutron. The ratio of 3He to 4He discriminates between terrestrial and 
extraterrestrial samples because cosmic helium has a relatively higher 
concentration of 3He. 
    This isn't the first time Becker and Bunch have uncovered 
extraterrestrial fullerenes. They found similar molecules in samples from the 
4.6-billion-year-old Allende meteorite that landed in Mexico three decades 
ago and inside Australia's Murchison meteorite. The Murchison samples 
contained helium gas rich in the isotope 3He just like the 
Cretaceous/Tertiary boundary clays. That's a sure sign that the buckyballs 
and their contents have a cosmic origin, said the researchers.
    In their most recent work, Becker, Bunch, and Robert Poreda (University 
of Rochester) examined the Cretaceous/Tertiary boundary layer because it is a 
well-studied sediment that contains extraterrestrial iridium. Minerals in the 
layer show signs that they once experienced temperatures greater than 2,000 C 
and pressures of about 400,000 atmospheres, presumably resulting from an 
asteroid impact. The scientists examined clay deposits in Denmark, New 
Zealand and North America. All of them contained fullerenes that encapsulated 
inert gases with unmistakable extraterrestrial and possibly extra-solar 
isotopic signatures.
    Becker said she hopes to expand the research to include other periods of 
mass extinction such as the even more devastating event that formed the 
250-million-year-old Permian/Triassic layer of sediment. Buckyball-encased 
gases in that layer could lend weight to the idea that global extinctions can 
have an extraterrestrial trigger. She added that she hopes to discover 
whether fullerenes on comets and asteroids delivered gases and carbon 
necessary to establish life on Earth. 
    "We now have a powerful new tracer to look at sediment layers very 
carefully," Becker said. "It opens new possibilities in looking at the 
problem of how planetary atmospheres evolved and maybe even how life evolved 
on Earth and perhaps on other moons and planets." 

Peace and grace,

Bill Olewiler+, OSL
United Methodist pastor, Virginia
<"}}}}><
BillRev@alumni.gwu.edu
. . . All manner of things will be well
    -- Julian of Norwich