Interplanetary dust particles , organic compounds

The importance of exogenous delivery of organic matter to the early Earth is critically dependent on the survivability of organic compounds during the delivery process. It is presently unclear exactly how much organic material would escape destruction during asteroid, comet and interplanetary dust particle infall to the Earth s surface. 

Meteorites from the asteroid belt are a potential source of some of the purine bases present in RNA. As asteroids travel in their orbits between Mars and Jupiter they collide with each other and pieces are broken off that vary in size from large bodies (potential meteorites) to dust particles. If the energy of the collision is great enough, this material is propelled out of its orbit into the interplanetary medium and some of the material eventually reaches the Earth. Approximately 10 kg of asteroidal material reached the primitive Earth s surface (6). This corresponds to a layer of material weighing 2x10 kg/m if spread uniformly over the surface of the Earth. The carbon content of the soluble organics present (1%) is equivalent to a layer of carbon compounds 25 m thick on the primitive Earth. Since meteorites contain about 1 ppm of purines and pyrimidines, then about lO kg of these compounds were on the primitive Earth. 

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