Generation Ships--- Can we build one now?

Umbran · Feb 16, 2019

dragoner said:
True, however we could find a rogue planet, current research says they might be more common than we previously thought.

I feel a need to quote Douglas Adams. “Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.”

"More common than previously thought," doesn't really help. You have this one thin line, from point A to B, in all the vastness of the interstellar vacuum. The chance that there will just happen to be a rogue planet close enough to your route to make a stop off for major mining operations is not credible. If they were common enough to be relevant, then over the course of our history they'd have been disrupting our solar system with flybys, and that hasn't happened. So, this is not a realistic scenario. Sorry.

Janx · Feb 16, 2019

Umbran said:
I feel a need to quote Douglas Adams. “Space is big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.”

"More common than previously thought," doesn't really help. You have this one thin line, from point A to B, in all the vastness of the interstellar vacuum. The chance that there will just happen to be a rogue planet close enough to your route to make a stop off for major mining operations is not credible. If they were common enough to be relevant, then over the course of our history they'd have been disrupting our solar system with flybys, and that hasn't happened. So, this is not a realistic scenario. Sorry.

Yeah, I just love how often crash landings on planets happen in sci-fi. I mean it's great that technology has developed so well that nearly all crashes are survivable, but how come everytime a ship-critical problem happens, a planet just happens to be nearby. That's like 1% of the entire time the ship is in transit. That's Murphy's Law throwing soft pitches.

dragoner · Feb 16, 2019

Mustrum_Ridcully said:
Not a direct source of power probably, but a source of resources (and if includes stuff like whatever we use in the reactors, an indirect source of power). Getting things up from a planet is costly, of course, but if it has the resources for it, it might work out in the end.

Do you mean that we would follow that rogue planet around? Because even if they are common, I don't think one could count on the ability of plotting a route that leads us near rogue planets often enough.

But an interesting side-topic - the science behind rogue planets: What would be the basis on assuming the frequency of rogue planets? I don't really know enough about planet formation and star formation to see why planets wouldn't form outside of star systems. It seems the fundamental is always the same - you have a collection of gas and materials, and their gravitational attraction brings them closer together until they collide and can't escape each other. I can somewhat see that a star forming means there is so much mass in the area that additional "mass clumping" are more likely.

Some people's logic seems so poor as their arguments against destroy themselves.

I go from astronomers, their papers, blogs, and such. As far as I have read, many of these rogues come from forming in proto-planetary disc and then being thrown out, often when larger bodies such as gas giants move in their orbits. As well as star systems where they were in stable orbits and the star had an event, and the planet wandered out of orbit. Billions of star systems over billions of years, that would increase incidence quite a bit. They could come from independent mass-clumping though, star that never came to be, and all that. The universe is orderly, yet also sublime.

I don't think a big generation ship vehicle would follow, or even stop at one of these rogues, most likely dispatch smaller vehicles to investigate or mine. For example, IIRC oxygen becomes ice at lower than 54 Kelvin, that could be mined. Then the smaller vehicles would then catch up to larger vehicle(s).

There is also a statement here that any generation ship simply must have the ability to maneuver, as without it, it could collide with something. In this, much as with the Mars cycler or other cycler orbits, the big generation ship could use momentum imparted by the gravity of the rogue in a slingshot manner. So this could make finding a rogue of even greater importance.

Shasarak · Feb 16, 2019

Janx said:
Yeah, I just love how often crash landings on planets happen in sci-fi. I mean it's great that technology has developed so well that nearly all crashes are survivable, but how come everytime a ship-critical problem happens, a planet just happens to be nearby. That's like 1% of the entire time the ship is in transit. That's Murphy's Law throwing soft pitches.

Do you mena that you dont read all of the sci-fi books about the ships that explode in space or get destroyed when they crash land on a planet? They usually have one great action scene at the start but I have to admit not much character development after that.

Hussar · Feb 17, 2019

Umbran said:
Yes, they are losing population, but not drastically. In the past decade, Japan has dropped from 127.8 million, to 126.8 million. That's less than one percent (it is 0.7% or so of the population, over an entire decade). In the long run, yes, you'd want to correct for it, but it isn't a situation to call for *forcing* people to have babies.

Expectations in Japan is that by 2050, Japan will be down to 60 million people. These predictions are being taken so seriously that Japan is currently changing its immigration laws to make it easier for foreign workers to work here. They are predicting massive worker shortages in very short order.

IOW, Japan is facing a very serious problem. And, one that a generation ship couldn't fix with immigration.

Shasarak said:
Do you mena that you dont read all of the sci-fi books about the ships that explode in space or get destroyed when they crash land on a planet? They usually have one great action scene at the start but I have to admit not much character development after that.

Ok, this? This was funny. :lol:

----

As far as "no romance" goes. If all you're doing is exploring, there are far, far cheaper, more effective, and safer ways of exploring the universe than a generation ship. Again, no society invests a significant portion of its resources on exploration just for the sake of exploration. Expecting the people of the Earth to invest a significant portion of the entire planet's resources for a significant length of time, just so a tiny handful of people will get to explore the universe is just not going to happen.

And, again, if we're talking 5 billion years in the future when our sun begins to expand, well, at that point we're into Dyson Sphere territory. Heck, by that time, you could probably harness the sun itself as your propulsion system, creating a Dyson sphere around the sun to house a virtually infinite number of people (yes, it's not infinite but, a Dyson Sphere with a diameter of, say, Venus's orbit, would have a surface area of a (not a mathematician) crap ton of Earths. IOW, it might not be infinite but, it could at least wave at infinity in the distance.

dragoner · Feb 17, 2019

Here is an article on propulsion that has some relevance to this discussion:

https://www.centauri-dreams.org/2019/02/15/breakthrough-propulsion-study

I like how he signs off:
Ad astra incrementis.

Samloyal23 · Feb 28, 2019

So what would be a good option based on current knowledge for a possible destination? Where should we go?

MarkB · Feb 28, 2019

Samloyal23 said:
So what would be a good option based on current knowledge for a possible destination? Where should we go?

It depends on what you want to do when you get there. We're getting better at identifying smaller, Earth-scale planets in other solar systems, but we can only detect the very broadest information about them. As it stands, we couldn't easily confirm whether a planet is capable of supporting any life, let alone human life.

If you want to go to a new solar system and then spend several hundred more years living in a tin can while you try to terraform an unknown world, there are some potential candidates - but you'd probably be better off staying here and doing the same thing to a world in this solar system.

Baron Opal II · Feb 28, 2019

A minimum population size would be 10,000 from papers I've read in the past. That would allow for sufficient genetic variation that recessives would get buried indefinetly or bloom and get selected out.

Apollo 13 survived a disaster fairly well. They had specific resources for a specific mission. When a disaster occurred and they had less resources than they needed to survive, the home team was able to come up with a solution that the astronauts could implement. Yes, in this situation communication times would make that less reliable, but there is still the possibility of communications for a while.

The Polynesian explorers colonized the islands in the South Pacific fairly handily. They certainly had a closed system as far as water went. And, they seemed to have moral certitude they were making the right decision for their unborn children. And, I'm certain that there were many ships that went out that didn't find anything and didn't come back.

Redundancy is key. Multiple systems, acknowledged societal systems to handle disagreements, perhaps ritualized combat (sports up to gladiators?), and multiple generation ships. Don't put your eggs in one basket.

Also- An O'Neil cylinder would be an exceptional first step. A dry run ferrying people and goods between here and Mars, even the Jovian colonies, would be good practice to determine unexpected needs.

Hussar · Feb 28, 2019

Baron Opal II said:
A minimum population size would be 10,000 from papers I've read in the past. That would allow for sufficient genetic variation that recessives would get buried indefinetly or bloom and get selected out.

Apollo 13 survived a disaster fairly well. They had specific resources for a specific mission. When a disaster occurred and they had less resources than they needed to survive, the home team was able to come up with a solution that the astronauts could implement. Yes, in this situation communication times would make that less reliable, but there is still the possibility of communications for a while.

I'll see your Apollo 13 with an Apollo 1 and raise you a Challenger. The problem with space travel is that when disaster hits, it's very often catastrophic.

And, once you're beyond a few light weeks, communication becomes largely impossible. Even a single light year. And we need to make at least 5 light years to make the nearest star. Communication with home to fix problems just isn't plausible for most of the journey.

The Polynesian explorers colonized the islands in the South Pacific fairly handily. They certainly had a closed system as far as water went. And, they seemed to have moral certitude they were making the right decision for their unborn children. And, I'm certain that there were many ships that went out that didn't find anything and didn't come back.

Yeah, because exploring in a tropical environment where food is plentiful and even water isn't all that difficult to come by in an area where it rains 300 days a year (yes, an exaggeration) is equivalent to space exploration. :erm:

And, never minding I'm not really interested in the moral arguments of a pre-industrial civilization. The notion that children would even have a say in things is a fairly modern concept. And, again, your children didn't have to keep exploring. They could always stay on whatever tropical island you found yourself colonizing. Or they could leave and go to a different island. IOW, they had considerable choice.

Redundancy is key. Multiple systems, acknowledged societal systems to handle disagreements, perhaps ritualized combat (sports up to gladiators?), and multiple generation ships. Don't put your eggs in one basket.

Also- An O'Neil cylinder would be an exceptional first step. A dry run ferrying people and goods between here and Mars, even the Jovian colonies, would be good practice to determine unexpected needs.

Now we're investing in multiple generation ships? Where exactly would the resources for this come from? We're talking an undertaking that, currently, would eat up the entire global output for decades just to create a single ship. And you want to make several?

Again, by the time you have that many resources at hand that you could feasibly build something like this, you no longer need to.