Editing Self-replicating spacecraft (section)

== Theory ==
Von Neumann argued that the most effective way of performing large-scale mining operations such as mining an entire [[natural satellite|moon]] or [[asteroid belt]] would be by self-replicating spacecraft, taking advantage of their [[exponential growth]].<ref name=Frietas1980>
{{cite journal
 | title= A Self-Reproducing Interstellar Probe
 | first= Robert A. Jr.
 | last= Freitas
 | journal= Journal of the British Interplanetary Society
 | volume= 33
 | pages= 251–264
 | year= 1980
 | bibcode= 1980JBIS...33..251F
 | url= http://www.rfreitas.com/Astro/ReproJBISJuly1980.htm
}}
</ref> In theory, a self-replicating spacecraft could be sent to a neighboring planetary system, where it would seek out raw materials (extracted from [[asteroid]]s, [[natural satellite|moons]], [[gas giant]]s, etc.) to create replicas of itself. These replicas would then be sent out to other planetary systems. The original "parent" probe could then pursue its primary purpose within the star system. This mission varies widely depending on the variant of self-replicating starship proposed.

Given this pattern, and its similarity to the reproduction patterns of bacteria, it has been pointed out that von Neumann machines might be considered a form of life. In his short story "Lungfish", [[David Brin]] touches on this idea, pointing out that self-replicating machines launched by different species might actually compete with one another (in a [[Darwinism|Darwinistic]] fashion) for raw material, or even have conflicting missions. Given enough variety of "species" they might even form a type of ecology, or – should they also have a form of [[artificial intelligence]] – a society. They may even mutate with thousands of "generations".

The first quantitative engineering analysis of such a spacecraft was published in 1980 by [[Robert Freitas]],<ref name=Frietas1980/> in which the non-replicating [[Project Daedalus]] design was modified to include all subsystems necessary for self-replication. The design's strategy was to use the probe to deliver a "seed" factory with a mass of about 443 tons to a distant site, have the seed factory produce many copies of itself there to increase its total manufacturing capacity over a 500-year period, and then use the resulting [[automatic factory|automated industrial complex]] to construct more probes with a single seed factory on board each.

It has been theorized<ref>{{Cite web|url=http://www.rfreitas.com/Astro/ComparisonReproNov1980.htm|title=Comparison of Reproducing and Nonreproducing Starprobe Strategies for Galactic Exploration|website=www.rfreitas.com}}</ref> that a self-replicating starship utilizing relatively conventional theoretical methods of interstellar travel (i.e., no exotic [[faster-than-light]] propulsion, and speeds limited to an "average cruising speed" of 0.1'''[[Speed of light|c]]'''.) could spread throughout a [[galaxy]] the size of the [[Milky Way]] in as little as half a million years.