How did the molecular building blocks for life end up on Earth? One long-standing theory is that they could have been delivered by comets. Now, researchers from the University of Cambridge have shown how comets could deposit similar building blocks to other planets in the galaxy.
In order to deliver organic material, comets need to be traveling relatively slowly—at speeds below 15 kilometers per second. At higher speeds, the essential molecules would not survive—the speed and temperature of impact would cause them to break apart.
The most likely place where comets can travel at the right speed are 'peas in a pod' systems, where a group of planets orbit closely together. In such a system, the comet could essentially be passed or 'bounced' from the orbit of one planet to another, slowing it down.
At slow enough speeds, the comet would crash on a planet's surface, delivering the intact molecules that researchers believe are the precursors for life. The results, reported in the Proceedings of the Royal Society A, suggest that such systems would be promising places to search for life outside our solar system if cometary delivery is important for the origins of life.
"Bouncing," or directed?
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