An interstellar conflict erupts which results in the home planet of one faction being completely decimated. (Use the impact in this
impact simulation as a reference for the scope of the destruction, in terms of energy released.)
Assuming the inhabitants have off-world colonies, and the desire to restore their planet; could the world be restored and repopulated within 1,000-5,000 years?
(Also, I apologise if this is the wrong place for this. I'm new.)
Ehhh... I suppose it depends on how much terraforming tech and resources the faction has to throw at the project, and how fertile/adaptive the species is. But my gut instinct is that there's no way you're going to just
undo something getting your planet turned into flaming popcorn like that. Not in 5,000 years.
That giant wall of flames and lava set everything on fire. The biosphere is gone. The oceans look... pretty gone, like they oceans were vaporized and turned to steam or something. That giant wound in the planet where the impact happened has got to be spewing out CO2, sulfur, and all sorts of other stuff like nobodys business and with all the photosynthetic plants incinerated, boiled, or otherwise wiped out the instantaneous change in climate, I don't see the plants being able to restore a nitrogen/oxygen mix on their own. I'm pretty sure the atmospheric mix of the planet would be suddenly changed to something like what the Earth was like when it was origionally cooling down millenia before the first photosynthetic life started showing up.
As for recolonization? Again, it kind of depends on what level of tech the faction has but unless they have access to self-replicating machines that can basically turn the molted hellscape into a machine world... and then selectively alter the terrain, atmosphere, and climate to turn it into a normal planet again and grow a whole new set of trees, soil microbes, plants, animals, fish, polinating insects, etc to give the planet a new biosphere... it's not going to happen. That impact killed the whole planet and trashed the biosphere. You either get a new planet or
make a new one out of the wreckage of the old one. This also assumes you have samples of all the necessary life forms and microbes to make a self-sustaining biosphere again.
As for repopulating the planet? Eh, probably though I don't think they
should. I'm sure if they have the tech to rebuild a planet, they'd have the tech to build a bunch of sealed environments on the surface to grow food and house people. So if they really wanted to they could have people living in bunkers of bubble domes while they watch the robots outside transform the burning twisted hellscape outside. On the other hand, they have definitive proof that civiliations can go to war and use weapons that wreck planets. The smarter thing to do would be to avoid being on a planet and just stick to spacefaring habitats or ships that are harder to hit with WMDs.
Soo yeah. It depends. But my gut instinct is that anyone with the resources to rebuild a planet after something like that probably wouldn't want to live on it again. They might invest resources into rebuilding it, or at least have some robots on the surface replicating and spreading to rebuild it or salvage things of historical significance, but the majority of people are going to avoid actually living on it again. They might rebuild it as something like a nature preserve or a place of historical significance with museums or tourist places... but they probably don't want massive number of people living on it (so there's fewer people to evacuate if another WMD heads to the planet), or they just avoid putting any major infrastructure there that would invite another attack. They keep all their military shipyards and command centers spread out in space instead of on big juicy smash-able planets.
