A Matter of Life

The rock was only lukewarm when it was picked up in a field near the southern Australia town of Murchison last year. By last week, it had become the hottest sensation in the scientific world. After carefully examining a chunk of the meteorite, NASA scientists reported that it contains the strongest evidence ever found that the chemical precursors of life can evolve elsewhere in the universe.

That evidence was in the form of 17 different amino acids found in the meteorite and identified by a team led by Ceylonese-born Cyril Ponnamperuma, 47. Significantly, half a dozen of those amino acids are among the 20 or so that are the building blocks of proteins--and thus of all terrestrial organisms. Convinced of the discovery's importance, the NASA team boldly asserted that it is "probably the first conclusive proof-of extraterrestrial chemical evolution."

Mirror Image. The NASA scientists are not the first to report finding amino acids in meteorites, which are believed to be fragments from the thousands of asteroids that circle the sun between the orbits of Mars and Jupiter. But previous claims have invariably been discredited because the amino acids were suspected to be of terrestrial origin; they could easily have contaminated the meteorites during or after their plunge through the earth's atmosphere. Even Ponnamperuma, a highly respected exobiologist (extraterrestrial biologist) at NASA's Ames Research Center in California, admits that only a thumbprint on a beaker could introduce amino acids into a meteorite sample. But his conclusion about the Murchison meteorite is strongly buttressed by other impressive evidence.

Besides the various amino acids, Ponnamperuma's team detected a greater proportion of carbon 13 than would be present in earthly organic matter. It also found a mixture of hydrocarbons curiously like that produced in experiments simulating the conditions of a primitive planetary atmosphere. The most compelling evidence was the nature of the amino acids themselves. Ever since Louis Pasteur's day, chemists have known that the atoms of organic compounds like amino acids can be assembled in two ways--one a mirror image of the other. Yet except for those made artificially, most amino-acid molecules found on earth have a "lefthanded" configuration; that is, beams of polarized light passed through them are rotated slightly to the left. When the NASA scientists examined the meteorite's amino acids, however, they discovered an almost equal division of left-and righthanded molecules. Thus, they concluded, it is highly unlikely that the amino acids could have been picked up in the atmosphere or in subsequent handling.

Coming only a short time after astronomers detected signs of such other organic compounds as methyl alcohol in giant clouds in the distant reaches of interstellar space, the meteorite findings add to the growing conviction that life may be more the rule than the exception elsewhere in the universe. They also may upset the accepted timetable for the initial stirrings of life on earth. In the traditional view, genesis occurred in the primordial seas several hundred million years after the earth's formation when random molecules of methane, ammonia, water and hydrogen accidentally came together, combined into amino acids and eventually gave rise to self-replicating proteins. If the new evidence is upheld, it would seem more likely that amino acids already existed when the earth and other parts of the solar system --including the asteroids--were born 4.5 billion years ago.

Pleased as they were by Ponnamperuma's report, NASA officials also had reason for embarrassment last week. After many months of preparation, the space agency launched its largest unmanned scientific satellite--a 4,680-lb. lab called Orbiting Astronomical Observatory B, designed to scan the heavens above the obscuring blanket of the earth's atmosphere. But as the $83.5 million package sped aloft from Cape Kennedy, the upper stage of the Atlas-Centaur carrier rocket failed to shed its protective fiberglass nose. The result was a rocketeer's nightmare: saddled with an extra ton of weight, the payload--including a powerful 38-in. telescope--failed to achieve orbital velocity and was apparently incinerated when it plunged back into the atmosphere over the Indian Ocean. To make matters worse, the mishap came only three weeks after the U.S. failed to put a missile-warning satellite into proper orbit over the U.S.S.R. and China. Total cost of the two flops: $145 million.

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