Our planet is dying. Cliche, I know, but unfortunately true and we do not have superpowers or the technology to build generation ships to escape. We have maybe a hundred years left, and we have decided that our best hope of leaving a lasting imprint on the universe is to try to make sure life does not die out, should it be that our planet was the only one on which it ever developed.

To that end, we have identified several nearby(ish) star systems with candidate habitable worlds and wish to create automated spacecraft that we can send out to bring about life on those worlds. Our technology level is roughly the same as modern human technology and our biochemistry is surprisingly similar (DNA, RNA, proteins, carbon-based metabolism, etc.)

What should go on the spacecraft to give the best chance of life taking root?

  • $\begingroup$ Painfully, I'm going to have to ask what definition of "life" you want to use. The more strict the definition, the harder it is to accomplish in a hundred years. $\endgroup$
    – Cort Ammon
    Mar 9, 2017 at 21:58
  • $\begingroup$ Water Bears. $\endgroup$
    – cobaltduck
    Mar 9, 2017 at 21:59
  • $\begingroup$ @CortAmmon, It's a last-ditch effort, so we'll take what we can get. It would be nice if intelligent life evolves again at some point, but we can't really predict that far ahead. Also, just to clarify, the 100 years is the time to prep and send out the spacecraft. The actual evolution of life from the packages might take another few billion years. $\endgroup$
    – Dan Bryant
    Mar 9, 2017 at 22:00
  • 1
    $\begingroup$ wikipedia has an article you should read $\endgroup$
    – user25818
    Mar 9, 2017 at 22:40

2 Answers 2


As simple as possible

You find the simplest, most robust organisms you can imagine. There are several extremophiles that are good candidates. Like for instance Deinococcus Radiodurans.

You want something that feeds off of simple materials and readily available energy. Anything that feeds off of light and air is good, like plankton. With a bit of luck they might settle on a water-world and start an oxygen revolution.

Of course you might also be introducing a hostile pathogen on an alien world, wiping it out pre-existing life...


If all you want to do is spread life at the most basic level, you can find bacteria that survive dormancy for extended periods of time. Pack them in golf ball sized spheres that can survive the heat of reentry due to ablation but will then crack upon impact. Then create one or more big cannons/rail guns/gauss cannons and start launching as fast as you can. The rotation of the planet will ensure a good spread that you can maximize by having a few that are aimed off of equatorial perpendicular.

If you keep the guns aimed into the galactic plane, you have an OK chance that some of them will hit planets.

If you want more precision, you can shotgun the areas near stars (where they will be in x thousand years).

  • $\begingroup$ Though, as MichaelK noted, this process might not be good if there is existing life. They wouldn't be too happy if, say, the town drunk were to poke it with a stick and get consumed by a ball of protoplasm that can only be stopped by extreme cold. $\endgroup$
    – ShadoCat
    Mar 9, 2017 at 22:47
  • $\begingroup$ From the pure physics of it point of view, I like this approach. It maximizes potential (tons of shots sent into the black) without putting too many eggs in one basket (a large seed ship heading to a single planet or system). The catch is you can't do this effectively and also architect the continuing evolution of the species, you're just shooting bacteria or fungi out and saying "good luck." To send out intelligence you'd need to plan target evolutions in specific environments, or go back to seed ships with some kind of AI architect to guide the early evolution stages. $\endgroup$
    – Ruscal
    Mar 9, 2017 at 22:57
  • $\begingroup$ I imagine the fraction of random orbits into a solar system that intersect a planet in a way that isn't guaranteed to kill everything is really quite small. $\endgroup$
    – user25818
    Mar 9, 2017 at 23:54
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    $\begingroup$ @notstoreboughtdirt, If the sphere is light enough, an atmosphere that is thick enough for life should decelerate it to a safe speed. $\endgroup$
    – ShadoCat
    Mar 10, 2017 at 17:39

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