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No. 93: May-Jun 1994

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From Dust Unto Dust

This Biblical assertion may be right on the mark, but in a sense that is slightly different from what is usually meant. The "first" dust may not have been terrestrial dust but interplanetary dust.

Let us commence with long-winged U2s cruising at 20 kilometers altitude or more. Collectors coated with silicone oil are deployed. To them stick tiny bits of interplanetary and interstellar debris that have been caught by earth's gravity and are slowly drifting downward in the atmospshere. Some of these micron-sized particles come from asteroid collisions; others from the disintegration of comets. This rain of cosmic matter is not negligible; the earth harvests about 40,000 tons annually from the fertile fields of outer space.

"Fertile?" Yes, outer space is a vast biochemical retort. D. Brownlee, R. Walker, and others:

"...suggest that interplanetary dust has probably carried organic matter to Earth since the early aeons of the solar system. The complexity of the organic molecules found on these particles has fueled the imaginations of many who ponder the role extraterrestrial matter may have played in the prebiological evolution of organic material on the primordial Earth."

Beyond these conjectures, several other things about interplanetary dust particles bother scientists:

"'What is surprising,' Walker notes, 'and still not understood, is the fact that the organic molecules we see in the dust particles are different from those previously seen in meteorites.' Another enigma is the observation of striking isotopic anomalies -- large enrichments of deuterium relative to hydrogen, as much as ten times greater than one sees in terrestrial samples -- in the particles in which Zare's group observed the organic molecules."

Yes, the original dust of life may have been extraterrestrial.

(Zeman, Ellen J.; "Complex Organic Molecules Found in Interplanetary Dust Particles," Physics Today, 47:17, March 1991.)

Comment. Nature it seems is a great recycler. It was Walt Whitman who wrote:

"And as to you, Life, I reckon you are the leavings of many deaths."

From Science Frontiers #93, MAY-JUN 1994. � 1994-2000 William R. Corliss