Date: Tue, 23 Feb 1999 20:36:55 GMT
From: Ron Baalke <BAALKE@kelvin.jpl.nasa.gov
Subject: [ASTRO] Researchers Find Clues To Life's Origin In Interstellar Clouds
Stanford University
CONTACT: David F. Salisbury, News Service
(650) 725-1944
2/18/99
A team of scientists from NASA and Stanford University have
created some of the chemicals essential for life in an environment similar
to that found in deep space. This finding could shed light on the origin of
life itself. The team reported its results in the Feb. 19 issue of the journal
Science.
Astrobiologists at NASA's Ames Research Center, Moffett Field,
Calif., and chemists at Stanford University conducted lab experiments to simulate
the conditions that exist in interstellar clouds of dust and gas. The dust
in such clouds plays an important role in the life cycles of solar systems.
It is the debris of previous generations of stars and the material from which
new stars and solar systems will develop.
To conduct their experiments, NASA scientists simulated the
dust clouds of the interstellar medium by freezing and then irradiating the
most common carbon-bearing molecules found there. The Stanford researchers
then analyzed the resulting chemical products. Their results confirmed the
presence of organics that served as the building blocks for the development
of life on Earth.
"We wanted to see what chemistry could occur under conditions
like those in molecular clouds — the places where solar systems are made,"
said Max Bernstein, principal author and chemist at Ames and the SETI Institute
in Mountain View, Calif. "The chemical compounds that resulted are similar
to those ubiquitous in living systems today, and play important roles in essential
biological processes," he said. "The importance of this work
is that it increases the odds that carbon-based life may have evolved elsewhere,"
said Richard Zare, chemistry professor and team leader of the Stanford collaborators.
"The molecules that we isolated in our lab experiments
may have been exploited by the Earth's earliest organisms. That may be how
these kinds of compounds become incorporated into our biochemistry,"
said Lou Allamandola, team senior researcher at Ames. "This is the dead
center of the astrobiology bull's-eye," he said, referring to Ames' core
space initiative for the 21st century.
The researchers think that the molecules they created in
the lab were biologically important for pre-biotic cells in two ways: quinones
(oxidized hydrocarbons that are present in St. John's wort, aloe and henna)
play a crucial part in electron transport in cells, and other by-products
of the experiment enable cells to harness light energy for photosynthesis.
The chemical products produced included quinones, aromatic ketones, alcohols
and ethers.
"The same kinds of compounds that we detected in our
experiments have been found in carbon-rich meteorites," said Scott Sandford
of Ames. "We are now seeing how these molecules in meteorites may have
formed."
In space, oxidized hydrocarbons (similar to those the researchers
created in the lab) are made in the interstellar medium and brought to Earth
in interplanetary dust particles (microscopic bits of comets and asteroids)
that drift down by the ton every day.
Previously, Allamandola showed that a family of carbon-containing
compounds, which are common on Earth in coal, soot and automobile exhaust,
are the most abundant class of organic molecules in the universe.
Bernstein, Sandford and Allamandola conducted the experiments
at the Astrochemistry Lab at Ames. The mass spectral analysis was carried
out at the Chemistry Department at Stanford University by graduate student
J. Seb Gillette, Simon Clemett, now at MVA Inc. in Norcross, Georgia, and
Zare.
