Changes

The generation objection by itself would not destroy panspermia. But the transference event requires a transit through space, followed by a passage through the earth's [[atmosphere]] and then an impact on the ground or at sea. Either of these events is fraught with danger. The unprotected space outside of an atmosphere is subject to unfiltered [[radiation]] in various forms. These include the products of [[radioactive decay]], [[cosmic rays]] (the highest-energy form of [[electromagnetic radiation]] known to man), and the [[stellar wind]], a stream of particles that fly out from any star as it continuously burns. Even if any life forms could survive the spatial passage, it must then somehow penetrate the atmosphere and risk incineration from sheer friction, and then must survive the impact.

The generation objection by itself would not destroy panspermia. But the transference event requires a transit through space, followed by a passage through the earth's [[atmosphere]] and then an impact on the ground or at sea. Either of these events is fraught with danger. The unprotected space outside of an atmosphere is subject to unfiltered [[radiation]] in various forms. These include the products of [[radioactive decay]], [[cosmic rays]] (the highest-energy form of [[electromagnetic radiation]] known to man), and the [[stellar wind]], a stream of particles that fly out from any star as it continuously burns. Even if any life forms could survive the spatial passage, it must then somehow penetrate the atmosphere and risk incineration from sheer friction, and then must survive the impact.

== Directed Panspermia ==

== Directed panspermia ==

In 1973, [[Francis Crick]], co-discoverer of [[DNA]], and [[Leslie Orgel]] proposed<ref>Crick, F. H. C., and Orgel, L. E. "Directed Panspermia," ''Icarus'', 19, 341 (1973).</ref> a new mechanism, which they called ''directed panspermia,'' to mitigate the hazards of transport and entry detailed above. They assume that an advanced [[civilization]] fired a brace of [[rocket]] [[missiles]], each laden with a [[payload]] of [[bacteria]] and/or [[blue-green algae]], in all directions. Crick and Orgel estimated that a payload of one [[metric ton]] could contain 10¹⁷ micro-organisms organized in ten or a hundred separate samples.

In 1973, [[Francis Crick]], co-discoverer of [[DNA]], and [[Leslie Orgel]] proposed<ref>Crick, F. H. C., and Orgel, L. E. "Directed Panspermia," ''Icarus'', 19, 341 (1973).</ref> a new mechanism, which they called ''directed panspermia,'' to mitigate the hazards of transport and entry detailed above. They assume that an advanced [[civilization]] fired a brace of [[rocket]] [[missiles]], each laden with a [[payload]] of [[bacteria]] and/or [[blue-green algae]], in all directions. Crick and Orgel estimated that a payload of one [[metric ton]] could contain 10¹⁷ micro-organisms organized in ten or a hundred separate samples.