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Feb. 18, 1999

Kathleen Burton

NASA Ames Research Center, Moffett Field, CA

(Phone: 650/604-1731)


David F. Salisbury

Stanford University, Stanford, CA

(Phone: 650/725-1944)

RELEASE: 99-11AR

ASTROBIOLOGISTS FIND CLUES TO ORIGIN OF LIFE

A team of scientists from NASA and Stanford University announced today that they 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.

Astrobiologists at NASA's Ames Research Center, Moffett Field, CA, and chemists at Stanford University, Stanford, CA, 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 University 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. The team reported its results in the Feb. 19 issue of the journal Science.

"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, Mountain View, CA. "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 University 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 bulls-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 which 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.

Drs. Max Bernstein, Scott Sandford and Louis 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 the team of J. Seb Gillette, Dr. Simon Clemett and Professor Richard Zare.

Astrobiology is the multi-disciplinary study of the origin, evolution, distribution and destiny of life in the universe. Ames Research Center is NASA's lead for astrobiological research and manages the agency's Astrobiology Institute. More information about Ames' Astrochemistry Lab can be found at:

http://web99.arc.nasa.gov/~astrochm/

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