In my story, humanity comes under attack by extraterrestrial forces determined to sieze Earth's resources. In my research it seems to be more plausible that aliens would attempt to exterminate humans by introducing a killer virus or Weapon of Mass Destruction rather than attempt a full-scale invasion.

I do not want to use the quite old concept of an alien killer virus or some giant space laser since contaminating or destroying the earth's surface is not their objective. So I am trying something rather unorthodox. My question is: is it plausible for aliens to use self-replicating drones to exterminate the human race?

  • $\begingroup$ Please contact me if you need me to clarify. Also, please explain to me how to @name somebody. Is it as simple as typing the name or do i have to hit their name as i am posting a comment like in some other social media platforms? $\endgroup$
    – user43914
    Commented Nov 2, 2018 at 15:12
  • $\begingroup$ Actually that is probably the more traditional alien invasion scenario where they attack in full force. $\endgroup$
    – anon
    Commented Nov 2, 2018 at 15:16
  • $\begingroup$ @Noah It almost worked for Ultron, didn't it? I should mention that it's your story, and you as an author can make almost anything sound believable. Is there a specific reason that makes you think it's impossible? The @ system works pretty much like you've described, use the @ symbol then follow it with someone's name. Make sure you don't have any spaces though, and spelling is important! You can try pinging me back if you'd like to check. $\endgroup$
    – Dubukay
    Commented Nov 2, 2018 at 15:29
  • $\begingroup$ Oh really? In most I've seen, its giant motherships, fighter ships, laser weapons, or actual foot soldiers. I figured that since invasions are expensive likely any smart alien would use a WMD to wipe out humanity versus a full scale invasion. I was asking instead of using a killer virus being that WMD, could they use drones? $\endgroup$
    – user43914
    Commented Nov 2, 2018 at 15:30
  • 2
    $\begingroup$ Self replicating drones are usually called Von Neumann probes, because self-replicating machines were studied (among myriad other things) by John von Neumann. John Ringo and Travis S. Taylor wrote a good science-fiction novel, Von Neumann's War (link goes to GoodReads), exploring the idea of a swarm of alien self-replicating robots using Mars as a staging ground for an invasion of Earth. $\endgroup$
    – AlexP
    Commented Nov 2, 2018 at 16:19

3 Answers 3


Plausibility depends on the constraints of the attack.

If your attack requires a massive saturation effort, then construction speed of the probes, as well as the visibility of the replication efforts will be major factors in how effective the attack is.

  • If the probes take too long to construct, then humanity will be able to destroy them faster than they can replicate, thus winning the invasion.
  • If they strip mine whole forests to replicate, then chances are they'll be spotted prior to reaching sufficient numbers to repel any disruption efforts humanity may muster.

The key is to ensure that the total population of the robots can out-replicate the attrition from attack and/or entropy.

This can be achieved in part by supporting the invasion from orbit with disruption of any means to coordinate a response; and with a sufficient number of probes dropped in the initial invasion.


They would use self-replicating nanobots that would turn people tissue into cancerous one. And they could be set to start turning off cells on set date so there would be no time for counter measure. You destroy humans and leave everything intact.


The viability of self-replicating drones depends on the materials the alien technology is composed of.

Let's imagine self-replicating human drones. Our technology is based on circuits and computer chips that require metals like copper and gold to transmit electrical signals. For chassies we can use a wider range of materials like metal, plastics, glass or even wood. Each material influences the properties of a drone like wheight and robustness.

If the alien technology is based on the same materials, they can harvest (or demolish) existing infrastructure like railways, junkjards, factories or cities to replicate. If they choose an industrialized country as starting point, these activities will be noticed very soon and humans might destroy the drones before they can replicate the necessary numbers. If they choose an undeveloped or uninhabitated area, they might lack the raw material to replicate.

If the alien technology is based on completely different materials than human technology they might be able to hide their activities far longer. It would take us some time to notice aliens harvesting sand in the Sahara or carbon from the atmosphere.

It might also be impossible to replicate enough drones due to a scarcity of the necessary materials on Earth.


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