Assuming you've got interstellar travel, and your setting can manage star-ships of (modern day) ocean liner size, what do you think is the maximum believable size for a planet (or system) evacuation, ala Battlestar Galactica?

50000?  100000?  1000000?  What, and why?

I ask because I'm spinning together a sort of hard-sf (-ish) universe, cobbling it together from a few different sources but I'd like to to have a unique spin on.

Like any NEO operation, it depends on the lift available.  The largest ever cruise ship seems to have a capacity of about 6500, so you could maybe triple that for short durations and uncomfortable conditions, hitting about 19500 per ship.  So 100 of those could evacuate about 2 million at one go.

Anyway, the details will depend on how much lift is available more than how many people they can get.  And how selective they are, I suppose.  If the tickets off the dying world are only available to the super rich, then i guess there would be a bit fewer applicants.

It totally depends on the infrastructure and culture, as well as the tech. The City of New Orleans can be evacuated in a few hours, and that's hundreds of thousands of people (getting them to go is the major issue, not capability).

Earth today could probably evacuate a dozen people to space with a week's notice and sufficient desperation (not that they'd last long up there).

On the other hand, the Enterprise alone could beam up around 50,000 people an hour (that's Kirk's Enterprise, the pad has 6 slots, and the whole process takes less than 10 seconds). If there's a nearby place to drop 'em off (eg, Mars, which I think had significant colonies in Kirk's time), or a shuttle system to accomplish same, we're talking a million a day, and that's one ship. I figure Sol would have at least a dozen ships with such capability (Federation Earth is almost certainly a major manufacturing/consumer/waypoint center) in the system at all times, quite possibly more if there are industrial transporters...and there probably are.

It might be better to look at proportions.

I imagine somewhere there are emergency evacuation protocols for islands, even major ones like Hawaii or Samoa. See what the experts there have to say as far as how many people they can evacuate in 24 hours (or whatever your time frame is), and look at what that is proportionally to the population of the island involved, to get some idea of what "typical" extinction-level emergency preparations are like.

thanks all, you've definitely given me some figures to work with.  This is a biosphere collapse decades in the making so the evacuation is by no means a rushed affair, nor is it "total".  some nations are roughing it out in L5 habitats, others are going on long-duration tours around the solar system with periodic refueling stops for reaction mass at Europa and Ceres, but there's a not insignificant number from the UA (United Americas) who are betting on the stars...but its still a pretty desperate time.

I think it depends mainly on how much time is available to build more evacuation ships.

Battlestar Galactica is an example of almost no time, and the only ships that survived the surprise decimation of 12 worlds were available.

StarCluster's sub-light Diaspora ships each were several kilometers long, and mostly hydrogen fuel tanks. At the very tip was a spinning wheel-shaped habitat section. Most of the people were kept frozen at any given time, to save on consumables, but they were awoken for shifts, as the cold sleep method used then allowed a slow aging to take place. These ships were generational, as the voyage took almost 2 thousand years. There were between ten and thirty thousand people on board, depending on the ship size. There were also frozen ova of millions more carried aboard. Parts of the ships held animal ova, and of course plants were vital for food and oxygen. These ships loaded at stations on the equatorial elevators. There were a fleet of landers for when they reached their destination.

-clash

With ample time and somewhere to go, I would expect a 90% evacuation.

If you wanted less than that, political considerations would be handy.  As in only some were allowed to leave.

33% of the population.  Hairdressers, middle managers, etc.  

Quote from: flyingmice;678839StarCluster's sub-light Diaspora ships each were several kilometers long, and mostly hydrogen fuel tanks. At the very tip was a spinning wheel-shaped habitat section. Most of the people were kept frozen at any given time, to save on consumables, but they were awoken for shifts, as the cold sleep method used then allowed a slow aging to take place. These ships were generational, as the voyage took almost 2 thousand years. There were between ten and thirty thousand people on board, depending on the ship size. There were also frozen ova of millions more carried aboard. Parts of the ships held animal ova, and of course plants were vital for food and oxygen. These ships loaded at stations on the equatorial elevators. There were a fleet of landers for when they reached their destination.

-clash

That's a good one, and I may steal parts of it - especially the frozen domestic animal ova.

Quote from: mcbobbo;678911With ample time and somewhere to go, I would expect a 90% evacuation.

If you wanted less than that, political considerations would be handy.  As in only some were allowed to leave.

As noted there was a huge evacuation, but the population had already been so winnowed down by famine, war and the general collapse caused by the coming breakdown that there weren't that many to evacuate (about 1.5bn).  

Also, when my campaign picks up the exodus has been going on for nearly a full generation: ships have failed (either hardware-wise, or socially), some turned back, others went off in different directions and not everyone left the Sol system to begin with.

So by the time the rag-tag refugee fleet arrives at the destination this campaign starts off in, there's about 2m souls left.

Another reason it took so long was the evac fleet was using the (theoretical but eminently plausible) Alcubierri warp drive - one of the potential problems with which is that a "bow wave" of high energy particles builds up over time around the warp bubble, and when the bubble is shut down, it all has to go somewhere and the theory is you'd basically (depending on how much energy was built up) get a hypernova-level explosion.  So ships periodically have to stop in normal space to bleed that off before it becomes problematic...

But I'm getting ahead of myself.

The biggest problem isn't transport. The bottleneck is getting people out of the gravity well and you're racing against the birth rate.

So ignore the ocean liner ships (unless they can somehow land) and figure out: how do we get out of the gravity well and what's the bandwidth in that method (in people) and how fast is the population breeding while you're doing it? For many realistic variables this results in no negative change in planetary population no matter how long you've got and how many people you ultimately move.

Quote from: Brad J. Murray;679288The biggest problem isn't transport. The bottleneck is getting people out of the gravity well and you're racing against the birth rate.

So ignore the ocean liner ships (unless they can somehow land) and figure out: how do we get out of the gravity well and what's the bandwidth in that method (in people) and how fast is the population breeding while you're doing it? For many realistic variables this results in no negative change in planetary population no matter how long you've got and how many people you ultimately move.

Yep! Even with multiple space elevators, hundreds of ships carrying tens of thousands of people each, and 150 years of feverish push, the most the StarCluster Diaspora managed was to slow down the population rise slightly. Much less significant than the decision by many not to have children when faced by immanent annihilation. The purpose was never to save anyone. They would all die on the journey out. The purpose was to not allow the species to die.

-clash

Maybe I'll have this as less of a diaspora and more of a decision by independent minded outer-solar-system dwellers to leave the Sol system behind.

Or possibly a BSG sort of thing - they were already out there puttering around when the Bad Thing(TM) befell earth.

Good advice all around, and I wish I chipped in earlier .

You may also wish to remember that military and government, as well as general people of importance and rich, will probably have their own side projects to take care of their evacuation.