Generation ships and aging.

[Flyndaran]

How would, or should, settings deal with the aging problem?
If you start out with a crew in their 20s, in 50 years, nearly everyone will be in their 70s.
Spaceships coasting through space aren't dangerous enough to lower life expectencies, so you'll eventually end up with everyone getting less and less capable and older and older with no room to add more youths.
Curing all age related diseases is an option, but not very realistic and comes with its own major setting issues.

[Peter Knutsen]

I really think it's up to the motivational factors that causes generation ships to be launched in the first place. Think about it. It's a huge endavour. It's a very long-term endavour.

It'll only get done if there is some very, very stark motivation behind it to finance something long-term, and 2ndly the people signing up to crew such ships also need to be extremely motivated.



So what kind of motivations lies behind it? Many reasons for doing the generation ship thing are nonsensical (e.g. "for the lulz") but after removing those you're still left with several non-nonsensical ones that are very different from one another.

Also think about health care. Obviously at higher Tech Levels, it gets easier to care for people who have become elderly and infirm but there is still some need. Retirement isn't just letting crew members retain their cabin, and giving them food, water, oxy and rplacement clothes, after they've become ex-crew members. You also have to care for them.

Unless they kill themselves (which is logical for certain brands of space colonization fanaticism), or unless the ship's goverance system does the killing (e.g. immediately upon a crew member bing deemed permanently unfit for activity duty, or after a traditional retirement period of perhaps 1500 days: "Citizen, your time is up, report to the nearest euthanasia department immediately!").

But still. Why do the generation ship thing? The motive matters a lot, the dual-motive of who does the funding, and who signs up to be a lifetime crewer and also accepting a duty to produce children who are destinied to not have the choice of doing anything other than crewing a ship that they didn't sign up for themselves.

Personally, I'm not going to have children, but if I were then I'm sure I'd be keenly interested in ensuring that they have a wide variety of options available for them in adult life, which is the exact opposite of the cul-de-sac that a generation ship is.



So what kind of person signs up to be a crew member?

Or maybe they don't sign up? Maybe they're conscripted. Usually conscription is done to the young and noneducated, but Haldeman's "Forever War" shows a rather reversed scenario.

[thrash]

Generation ships should start out with the demographic profile they intend to maintain, with maybe some room for fluctuation on the high side. One wouldn't start with nothing but adults. The hard part is predicting how that profile will adjust to the ship itself and making allowances for the adjustment.

STL ships that intend to finish up in a single lifetime are different, of course.

[Flyndaran]

The distribution of crew age will increase to a mushroom shape rather than the triangle it's been for most of our history.

After a few generations, how you started out wouldn't matter. Only how it's enforced would.

[Johnny1A.2]

Originally Posted by Flyndaran

How would, or should, settings deal with the aging problem?
If you start out with a crew in their 20s, in 50 years, nearly everyone will be in their 70s.
Spaceships coasting through space aren't dangerous enough to lower life expectencies, so you'll eventually end up with everyone getting less and less capable and older and older with no room to add more youths.
Curing all age related diseases is an option, but not very realistic and comes with its own major setting issues.

What problem is that? The female fertility rate would have to be matched to the mortality rate so that the population stayed more-or-less stable, with a workable age spread. It's likely that whatever hard physical labor was done by humans would be done by the young, while the older citizens did more sedentary tasks, but that's no different than anywhere else, really.

It's unlikely a ship big enough to function as a generation ship at all would have a big problem with having a percentage of its population elderly at any given time. A ship too small to manage that probably can't manage a multigenerational star voyage anyway.

Now, you would have to recycle the bodies of the dead, in some way, of course, but that just comes with the territory.

[Johnny1A.2]

Originally Posted by Flyndaran

The distribution of crew age will increase to a mushroom shape rather than the triangle it's been for most of our history.

Not if the female fertility rate matches the mortality rate.

[Peter Knutsen]

Originally Posted by Johnny1A.2

Now, you would have to recycle the bodies of the dead, in some way, of course, but that just comes with the territory.

I'm not sure that's strictly necessary. Not doing it comes with a great cost, but if the motivation for the generation ship project is that particular kind of irrational, then they might be willing to lift such a burden.

[Flyndaran]

Originally Posted by Johnny1A.2

Not if the female fertility rate matches the mortality rate.

Aging or death are the only options. I assumed dangerous overpopulation or mass decimation aren't options.

[David Johnston2]

Originally Posted by Flyndaran

How would, or should, settings deal with the aging problem?
If you start out with a crew in their 20s, in 50 years, nearly everyone will be in their 70s.

Well no, they won't. Generation ships are called that for a reason. It is of course essential not to launch your generation ship already full. You need to allow for some population growth. Ideally a fair bit since you don't really need a full complement until just before arrival. I mean all the crew really has to do is maintenance and monitoring of the reactor and the life support systems until you are in the final stretch and actually colonizing calls for almost completely different skill sets. Generation ship life is oppressive enough without having to micromanage birth to match death.

[Flyndaran]

That still means eventually it will become the ship of senior moments.
As long as the ship can run itself, it's not an impossible problem. But that still leaves the colonization phase with very few fertile individuals.