How long would it take to terraform a lifeless but somewhat earthlike planet using bacteria, fungus, seeds and eggs?

What are realistic time-schedule expectations for far-future terraforming and developing earth-like plant and animal/fish/bird populations on distant planets, by means of robotic space probes with "seed" technology such as bacteria that converts atmosphere, seeds, bionegineered eggs, etc.?

The idea is that robot probes would be sent to distant star systems with equipment to analyze local planets and asteroids, set up automated production of bacteria and/or fungus to drop onto the best planets, designed to be able to survive and convert local materials into a biosphere, and later to drop other bacteria, fungus, then seeds and eventually eggs for insects, fish, birds, and even animals.

The question is, assuming it's conceivably possible to develop this technology given enough time and resources, how long might it take to advance a lifeless alien planet with otherwise earth-like properties (i.e. .7 to 1.5 earth mass, some existing atmosphere, magnetic field, not utterly frozen nor too hot) to the next stages such as:

1. Atmosphere that can support more than bacterial life. This would obviously be highly-dependent on the starting atmosphere and materials available, but in general, how fast might this be doable by dropping purposely-chosen bacteria onto a planet?
2. Some earth plants/insects can survive somewhere on the planet.
3. Some earth fish/animals can survive somewhere on the planet.
4. Most earth animals/humans can survive on the planet.

For each level, would it take decades? Centuries? Millennia?

Background information:

• Time/setting: Up to 20,000 years in the future, following optimistic peaceful resolution of current self-destructive stupidity on Earth.
• Technology: Realistic extrapolations of modern science. There may or may not be FTL technology, but it is limited - distances are still an issue and it requires significant time and resources to travel to other star systems.
• Space program: Space stations with large permanent human populations, "domed" planetary colonies, and various space industries have been developed. Some colonization of other star systems has occurred.

Related idea from an answer by Black to a question about terraforming:

It would be nice to have biomass on a planet before you got there. As well as any target byproducts you might engineer them to make. I'd add that Deinococcus radiodurans can survive anywhere you can't engineer other bacteria to. So you're pretty much guaranteed to be able to just launch a can across the universe at any planet, even if you can't quite fly to it yet. If your lucky the locals may have evolved before you got there and be able to contribute to science with their "un-poisoned" paradigms. (Panspermia anyone?)

posted almost 10 years ago

Dronz‭

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