The concept of self-replicating spacecraft, as envisioned by mathematician John von Neumann, has been described by futurists and has been discussed across a wide breadth of hard science fiction novels and stories.
[2] In theory, a self-replicating spacecraft could be sent to a neighboring planetary system, where it would seek out raw materials (extracted from asteroids, moons, gas giants, etc.)
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 Darwinistic fashion) for raw material, or even have conflicting missions.
The first quantitative engineering analysis of such a spacecraft was published in 1980 by Robert Freitas,[2] in which the non-replicating Project Daedalus design was modified to include all subsystems necessary for self-replication.
In 1981, Frank Tipler[4] put forth an argument that extraterrestrial intelligences do not exist, based on the fact that von Neumann probes have not been observed.
Now known as Sagan's Response,[citation needed] it pointed out that in fact Tipler had underestimated the rate of replication, and that von Neumann probes should have already started to consume most of the mass in the galaxy.
Another objection to the prevalence of von Neumann probes is that civilizations that could potentially create such devices may have a high probability of self-destruction before being capable of producing such machines.
[2] It is a concatenation of two concepts: a Von Neumann universal constructor (self-replicating machine) and a probe (an instrument to explore or examine something).
[2] Such constructs could be theorised to comprise five basic components (variations of this template could create other machines such as Bracewell probes[jargon]): Andreas M. Hein and science fiction author Stephen Baxter proposed different types of von Neumann probes, termed "Philosopher" and "Founder", where the purpose of the former is exploration and for the latter preparing future settlement.
[citation needed] Physicist Paul Davies of University of Adelaide has "raised the possibility of a probe resting on our own Moon", having arrived at some point in Earth's ancient prehistory and remained to monitor Earth, a concept that, per Michio Kaku, was what Stanley Kubrick used as the basis of his film, 2001: A Space Odyssey (though the director cut the relevant monolith scene from the movie).
[citation needed] Anders Sandberg and Stuart Armstrong argued that launching the colonization of the entire reachable universe through self-replicating probes is well within the capabilities of a star-spanning civilization, and proposed a theoretical approach for achieving it in 32 years, by mining planet Mercury for resources and constructing a Dyson Swarm around the Sun.