Animals for a colony ship

[Battlehymn Republic]

Say it's a Sid Meier's Alpha Centauri-type situation and a colony ship equipped with the usual handwavium cryosleep pods for 100-500 people is heading for a distant planet which has , but can be eventually terraformed over centuries but currently has a surface hostile to Earth life.

Aside from the requisite DNA banks, should any animals be brought aboard?

[The Romulan Republic]

First of all, bring animals that can be used for food, obviously. For example, I've read about the idea of having fish tanks on space stations.

You probably don't want anything big, or requiring lots of food. Obviously, the heavier your cargo, the more expensive it will be to ship it. You might want to try taking genetic material of a bunch of animals, and growing them in test tubes once you get their. Would that be feasible?

[Turin]

A great many food plants (which you'll be bringing with you, obviously) require pollination. You'll need to bring along whichever species of insect pollinates whichever plants you bring. And you may need other species, like ants, to properly develop the soil that you intend to seed those plants in. And for every species you bring, you may need to bring various symbiotic species as well -- some ants "farm" aphids and various fungi.

As a result, I always question the idea of bringing an ecosystem in stasis (or other "shake and bake" terraforming ideas). I think ideally you'd want a working ecosystem running completely isolated on Earth for a good long while and then bring it with you and keep it running the whole way.

[Starglider]

As a result, I always question the idea of bringing an ecosystem in stasis (or other "shake and bake" terraforming ideas).

It sounds like you just need to be thorough and test your ecosystem-startup techniques in a heated dome in antarctica (or rather a completely isolated but relatively cheap testbed) before risking an interstellar mission on them.

I think ideally you'd want a working ecosystem running completely isolated on Earth for a good long while and then bring it with you and keep it running the whole way.

Unfortunately the mass penalty for doing this is very high, and interstellar travel (without magic FTL drives) is already very very energy-intensive. You could go very slowly but that runs into other engineering problems on top of the 'no payback to the builders in any reasonable timeframe' problem.

Personally I think that if you have the technology base for interstellar travel and terraforming in the first place, you'd use some serious genetic engineering and Von-Neumann machines at the very least and probably some sophisticated nanotech too to drastically cut the bootstrap requirements. All you really need are the fertilised gammetes and a bank of artificial wombs in a few standard sizes, and if you can engineer 'generic stem cells' such that you can just store all the DNA patterns in computer memory and sequence it as required all the better. You'd probably bring just a few genetically engineered species of bacteria to help with the initial terraforming and also to be cultured in big vats by the robots to generate nutrients for the artificial wombs - unless you nanotech is so good it outperforms bacteria in these roles. This should keep the payload mass for your interstellar mission down low enough that it can be accomplished in a (relatively) reasonable amount of time and energy.

[Turin]

As a result, I always question the idea of bringing an ecosystem in stasis (or other "shake and bake" terraforming ideas).

It sounds like you just need to be thorough and test your ecosystem-startup techniques in a heated dome in antarctica (or rather a completely isolated but relatively cheap testbed) before risking an interstellar mission on them.

"Cheap" compared to the interstellar mission, of course. Presumably if you're going through the trouble at all, you're talking about a mission where you want the chance of failure to be the minimum possible. That means a lot of testing, but I get your point.

I think ideally you'd want a working ecosystem running completely isolated on Earth for a good long while and then bring it with you and keep it running the whole way.

Unfortunately the mass penalty for doing this is very high, and interstellar travel (without magic FTL drives) is already very very energy-intensive. You could go very slowly but that runs into other engineering problems on top of the 'no payback to the builders in any reasonable timeframe' problem.

The OP doesn't go into the builders' motivations, but maybe we're talking about a situation of continuation of the species in the event of some kind of impending catastrophe. Or, as I postulate below, you've got some non-obvious reason for sending out these seed ships (like religion). The mass penalty for a running ecosystem is going to be high, but remember per the OP we've got actual living humans coming with us.

Personally I think that if you have the technology base for interstellar travel and terraforming in the first place, you'd use some serious genetic engineering and Von-Neumann machines at the very least and probably some sophisticated nanotech too to drastically cut the bootstrap requirements.

Does that follow? The primary technological hurdle for interstellar travel would be power requirements. You can have the power technology and not have developed or have access to nanotech or genetic engineering. One could easily imagine the civilization who would go through all the trouble to do this doing so for "religious" reasons, and they might have some kind of superstition against genetic engineering.

All you really need are the fertilised gammetes and a bank of artificial wombs in a few standard sizes, and if you can engineer 'generic stem cells' such that you can just store all the DNA patterns in computer memory and sequence it as required all the better. You'd probably bring just a few genetically engineered species of bacteria to help with the initial terraforming and also to be cultured in big vats by the robots to generate nutrients for the artificial wombs - unless you nanotech is so good it outperforms bacteria in these roles. This should keep the payload mass for your interstellar mission down low enough that it can be accomplished in a (relatively) reasonable amount of time and energy.

You're assuming a non-trivial amount of additional available technology here. Under this scheme, you'd need an AGI with (presumably human-like) robotic avatars in order to raise your human beings. Or you have human beings "on ice" as per the OP, in which case you're running into the original mass penalty problem this whole thing was supposed to solve, right?

[Starglider]

Presumably if you're going through the trouble at all, you're talking about a mission where you want the chance of failure to be the minimum possible.

That's another argument against taking a live biosphere actually. If any of the thousands of variables goes out of balance during the multi-decade trip, the biosphere dies and you lose everything. Any disaster (e.g. micrometeoroid impact) causing major loss of atmosphere/volatiles is likely to end your trip as well. Radiation shielding will be a huge problem since you've got a large system volume and any accumulation of mutations could kill the viability of your ecosystem. You could solve problems (2) and (3) by hollowing out a huge asteroid and accepting a very slow journey, but that makes (1) even worse. Experiments to date with sealed multi-year biospheres haven't been encouraging.

Cryo-pods avoid the whole ecosystem stability risk, and if there is a disaster en-route that doesn't cause a total loss of the vehicle you only lose a fraction of your specimens (e.g. a high radiation dose might sterilise some but not others). Gene sequencers and artificial wombs are the lowest risk because you can implement massive redundancy and error correction in the genome storage, and equipment failures/losses only reduce your revival rate, they don't deprive you of critical species.

The OP doesn't go into the builders' motivations, but maybe we're talking about a situation of continuation of the species in the event of some kind of impending catastrophe. Or, as I postulate below, you've got some non-obvious reason for sending out these seed ships (like religion).

True. I guess I implicitly assumed the Civ scenario of human civilisations trying to establish colonies in under a century.

The primary technological hurdle for interstellar travel would be power requirements. You can have the power technology and not have developed or have access to nanotech or genetic engineering. One could easily imagine the civilization who would go through all the trouble to do this doing so for "religious" reasons, and they might have some kind of superstition against genetic engineering.

Again this is highly unlikely for humans in any scenario close to real history, but certainly if you widen the parameters this could be true.

You're assuming a non-trivial amount of additional available technology here. Under this scheme, you'd need an AGI with (presumably human-like) robotic avatars in order to raise your human beings.

The OP seemed to imply that a fair number of humans were coming via the cryo route, and the question was how to pack the rest of the ecosystem in. Obviously if human experts are available you don't need AGI, they can supervise more limited automation, though as ever AGI would make everything easier. I suspect quite a large adult:child ratio (>10:1) could actually be sustained, if automation can remove the requirement for the humans to spend all their time building the infrastructure.

Or you have human beings "on ice" as per the OP, in which case you're running into the original mass penalty problem this whole thing was supposed to solve, right?

Carrying large numbers of complete humans is a challenge but an order of magnitude easier than carrying an entire frozen ecosystem, which is itself about two orders of magnitude easier than carrying an entire live ecosystem that will be viable for several decades (or centuries) before being 'unpacked'. Given sufficiently advanced technology you could do what most of the

cryopreservation

are doing; just freeze people's heads, clone new bodies from stem cells at the other end. Further progress allows mind-state recording and complete, direct resurrection of humans from digital storage, but that probably does require your crew to have got over the whole 'continuity flaw' neurosis.

[Gil Hamilton]

I would think it would be easier to not bother with fully grown animals and stick with a handful of them in the same cryostatus you've got the humans in and the rest as fertilized cells. That was you can thaw out the critters when you are on site and then in vitro fertilize them so they give birth to the first generation. I say bring adults of the species along so the babies have something of their species to raise them and teach them how to be good cows or horses or dogs or whatever.

As for food, people can get by on engineered bactries and algae farms. If people really have the taste for meat, you don't need to bring a cow for slaughter... just freeze dry the steaks before you live and pack them. However, I can see the value on having an in-ship farm with a complete biosphere set up. Particularly if you could double it as a park for people to hang out in on off hours.

[Tasoth]

Someone already stated pollinators for your crops, but no one has mentioned fungi responsible for mycorrhizae relationships. And since it might be easier to GM fungi over plants (no clue on this one, not a geneticist), adjusting the rate and what nutrients they extract from the soil could be done on landing or before setting out.

Additionally, ratters of some sort. If there's an indigenous vermin analogue on planet, you'll want them out of your crops and stores. I also have no clue as to whether rats would be able to survive if they stowaway. But if they do, ratters would be a nice complement to the settlement.

The idea of a handful of frozen live animals plus a large supply of frozen embryos is a good idea as long as some fluke accident doesn't occur. If the tech would be available, stashing some kind of back up artificial womb in the cargo would be beneficial.

Personal opinion though, if the data is available, look for indigenous species that can be exploited in similar roles as ones we use already. If you can get away with limit the species you introduce to a new ecosystem, then that's a good thing.

[Shroom Man 777]

It would be crazy if you could have some kind of biotechnological ovipositor that you can just command to lay eggs containing pre-programmed animal babies. A bit like the Queen Alien from Aliens, except it lays kittens and horsies instead of acid-blooded monstrosities.

[Junghalli]

It depends on what kind of colony you're planning to set up, and what your tech base is.

Can you simply directly synthesize nourishing and tasty food? If so, there's no reason to bother with plants or animals. A synthesizer will probably be much more efficient. Though you may take some plant and animal genomes as a long-term contingency. This is the approach I go with for my own uni.

Is the planet's surface survivable? Are you planning to "go back to the soil" (i.e. live as subsistence farmers on the surface), or are you planning to live in a sealed self-contained base, at least initially (realistically much more sane). If the former, you may take genomes for various kinds of domestic animals. If the latter, you're probably mostly going to take food animals that don't need much room (fish and other small marine creatures, probably), and whatever insects the plants in your self-contained ecology will need. Though you may take records of the genomes of all sorts of species, just as a long-term contingency plan.

Are you planning to terraform the new planet? If so, you will need to be thinking about stocking its ecosystem with the necessary keystone species, and you'll probably bring DNA records of all sorts of animals with you, and equipment to clone them in vast numbers (or equipment to build the cloning equipment anyway).

Are you worried at all about what might happen if the colony's civilization ever collapses, or do you figure if that happens they're gonners anyway? If you are, you might bring DNA records for all the animals and plants you'd need for a subsistence agricultural society (oxen, horses, wheat etc.).

In any case, I don't think carrying actual live animals, even in stasis, is going to be worth it unless you have a massive generation ship with its own fully functioning self-contained ecology. It'll be easier just to carry a bunch of frozen embryos, or maybe just DNA records in the computer and generic stem cells, and clone the animals you want in artificial wombs.

Additionally, ratters of some sort. If there's an indigenous vermin analogue on planet, you'll want them out of your crops and stores. I also have no clue as to whether rats would be able to survive if they stowaway. But if they do, ratters would be a nice complement to the settlement.

Assuming you're going with the option of keeping the crew in stasis, making sure unwanted mammalian stowaways don't come along for the ride should be pretty easy. Just don't bother maintaining a survivable environment in the living quarters for the duration of the trip. It's a waste of energy, the crew won't need it, it increases wear and tear on the life support system, and all the stuff will probably last better in hard cold vacuum anyway.

As for native vermin, realistically they'd probably find our crops to be nasty-tasting nutritionless pap at best and deadly poison at worst. Totally alien biochemistries. The same, in reverse, applies to things from Earth trying to eat native vermin, so if you need a ratter you'd probably be better off domesticating some local critter.

[His Divine Shadow]

I think it would be best to take only genetic materials, maybe even in a digital form, and then synthesize and grow lifeforms later when you have arrived. Of course that requires pretty advanced tech but I don't see it as terribly outlandish.

[Shroom Man 777]

Hence you'd need a freakish biotechnological ovipositor and a conveyor belt to sort your beautiful creations! Gentlemen, behold!

I guess it'd be a bit like Titan A.E., minus creating a New Earth by sucking the souls of evil energy entities.

[Turin]

Presumably if you're going through the trouble at all, you're talking about a mission where you want the chance of failure to be the minimum possible.

That's another argument against taking a live biosphere actually. If any of the thousands of variables goes out of balance during the multi-decade trip, the biosphere dies and you lose everything.

I'll concede that.

The OP doesn't go into the builders' motivations, but maybe we're talking about a situation of continuation of the species in the event of some kind of impending catastrophe. Or, as I postulate below, you've got some non-obvious reason for sending out these seed ships (like religion).

True. I guess I implicitly assumed the Civ scenario of human civilisations trying to establish colonies in under a century.

Oh, under a century? (I'm only loosely familiar with the Civ game in question.) Well, my only point with that is that the builder's motivations may rule out certain approaches, like building everyone up from gene banks or using your favorite "downloads" method.

The primary technological hurdle for interstellar travel would be power requirements. You can have the power technology and not have developed or have access to nanotech or genetic engineering. One could easily imagine the civilization who would go through all the trouble to do this doing so for "religious" reasons, and they might have some kind of superstition against genetic engineering.

Again this is highly unlikely for humans in any scenario close to real history, but certainly if you widen the parameters this could be true.

At the risk of a thead hijack, why not? My own country is a good example of one where advances in space travel have been coming alongside enormous superstitions around genetics. I'm not sure you can just assume this gets handwaved away.

You're assuming a non-trivial amount of additional available technology here. Under this scheme, you'd need an AGI with (presumably human-like) robotic avatars in order to raise your human beings.

The OP seemed to imply that a fair number of humans were coming via the cryo route, and the question was how to pack the rest of the ecosystem in.

I agree, but the whole concept of building everything up from gene banks will want to bypass this -- the humans will have to be supplied for the period between being thawed out and having an entire ecosystem up and running. But this might actually be moot, as I've thought of an additional complication (see below).

Or you have human beings "on ice" as per the OP, in which case you're running into the original mass penalty problem this whole thing was supposed to solve, right?

Given sufficiently advanced technology you could do what most of the cryopreservation are doing; just freeze people's heads, clone new bodies from stem cells at the other end. Further progress allows mind-state recording and complete, direct resurrection of humans from digital storage, but that probably does require your crew to have got over the whole 'continuity flaw' neurosis.

I'd rather not introduce that debate into the thread, as it's been had elsewhere, but it does run headlong into the superstition objections I raised earlier. That being said, it's also probably the most viable for the reasons I'll outline below.

It depends on what kind of colony you're planning to set up, and what your tech base is.
<snip>
Are you planning to terraform the new planet?

Junhalli has reminded me of another major complication. If you intend to terraform the planet, you're going to go through a long period of time where the surface isn't habitable while it makes the transition. You'll need not only the species you need for your "goal ecosystem," but also the species you'd need to help you terraform the planet in the first place -- you'll need oxygen creating bacteria, all the various species that will build your soil, and plenty of non-food plants. If we assume our builders have the technology base (and patience) to do this, we still need somewhere for the humans to live while we're doing all the work. Which means either keeping them on ice (either cryo or digital, it doesn't matter really) for a very long time and thawing them out after your machine intelligences have done all the work, or building an isolated ecosystem for them in a habitat. And if you can build a reliable isolated ecosystem, why bother going through all the trouble of sending out your colony through interstellar space in the first place? The return on investment doesn't seem like it could ever be worth it without non-economic motivations.

[GrandMasterTerwynn]

Say it's a Sid Meier's Alpha Centauri-type situation and a colony ship equipped with the usual handwavium cryosleep pods for 100-500 people is heading for a distant planet which has , but can be eventually terraformed over centuries but currently has a surface hostile to Earth life.

Aside from the requisite DNA banks, should any animals be brought aboard?

No. The sort of ecosystem you will be introducing to a planet you are terraforming will be comprised of simple, hardy organisms. It will probably consist of algae, or photosynthesizing bacteria analogous to those that you might find at the heart of your colony ship's life-support systems which will colonize wherever the planet may currently be, or will eventually be wet. Later on, you'd introduce lichens and genetically engineered mosses for the land, and, eventually protozoans and simple fungi. Essentially, you'd be turning the planet into a large-scale version of your starship's life-support system. After a millennium or two, you might be ready to introduce some especially hardy vascular plants (i.e. conifers.) Maybe even ones with flowers (but only the wind-pollinated ones.)

This suggests that any macroscopic ecosystems you will be introducing to the planet will be aquatic ones. Which means, if you are bringing animals . . . they'll be fish, crustaceans, and molluscs. If you were feeling especially ambitious, you could also bring amphibians. And, for the cost of storing a few humans in cryopods, you could conceivably bring millions of their eggs without having to worry about what to do with their parents (as there are numerous species of the above that require zero parental care.)

[GrandMasterTerwynn]

It depends on what kind of colony you're planning to set up, and what your tech base is.
<snip>
Are you planning to terraform the new planet?

Junhalli has reminded me of another major complication. If you intend to terraform the planet, you're going to go through a long period of time where the surface isn't habitable while it makes the transition. You'll need not only the species you need for your "goal ecosystem," but also the species you'd need to help you terraform the planet in the first place -- you'll need oxygen creating bacteria, all the various species that will build your soil, and plenty of non-food plants.

Your terraforming ecosystem ought to be the same as the one in your ship's closed-loop life-support system. Which means your goal ecosystem should be that ecosystem with as simple a macroscopic ecosystem as you can get away with.

If we assume our builders have the technology base (and patience) to do this, we still need somewhere for the humans to live while we're doing all the work. Which means either keeping them on ice (either cryo or digital, it doesn't matter really) for a very long time and thawing them out after your machine intelligences have done all the work, or building an isolated ecosystem for them in a habitat.

The smart thing to have done would've been to dispatch your machine intelligence and the seeds for a basic ecosystem aboard something capable of moving at something really fast. That way, most of the groundwork would've been completed by the time your slowship arrives (and barring a handwavium drive, the human-occupied ship will likely take centuries to reach its destination. After all, all those corpsicles and their fancy life-support system will require copious quantities of really heavy shielding . . . much more than that required to shield an adequately-hardened machine intelligence and a single well-shielded cryopod filled with the frozen cells of your basic terraforming ecosystem. The terraforming ship would only need decades to complete its trip.) Of course, if you're bringing everything aboard one ship, your decision whether or not to keep the colonists on ice will depend on how long the warranty on those cryopods or digital storage media is.

If you're thawing them out early, why stick them in a habitat on the surface? It'd probably be safer to build a closed-loop ecosystem inside a hollowed-out asteroid and establish your first colony there while you wait. That way, by the time the planet becomes viable, you'd conceivably be able to drop a population of thousands on it in numerous self-sustaining settlements.

[Junghalli]

And if you can build a reliable isolated ecosystem, why bother going through all the trouble of sending out your colony through interstellar space in the first place? The return on investment doesn't seem like it could ever be worth it without non-economic motivations.

Most likely anybody who can send a ship to another star system isn't going to strictly need Earthlike planets anymore. Starships imply space industry, which implies having solved most or all the major problems with living in space, which means you can live anywhere you can find raw materials if you have to. Terraforming would be something you do to improve the local real estate value, not because you strictly have to.

Your terraforming ecosystem ought to be the same as the one in your ship's closed-loop life-support system. Which means your goal ecosystem should be that ecosystem with as simple a macroscopic ecosystem as you can get away with.

Of course, that assumes the terraformers are thinking strictly in terms of maximizing efficiency. Personally, if I was terraforming a new planet I would want an end-state a bit less minimalistic than algae and banana tree world, just because the idea profoundly offends my aesthetic sense. Terraforming is already a sentimentalist project anyway: if all you care about is efficiency just live in bases in the asteroids.

[Ender]

Horses. It is going to be quite some time before your colony is going to be in a position to build tractors, cars, and trucks. Horses will provide the ability to fill that gap.

[Turin]

If you intend to terraform the planet, you're going to go through a long period of time where the surface isn't habitable while it makes the transition. You'll need not only the species you need for your "goal ecosystem," but also the species you'd need to help you terraform the planet in the first place -- you'll need oxygen creating bacteria, all the various species that will build your soil, and plenty of non-food plants.

Your terraforming ecosystem ought to be the same as the one in your ship's closed-loop life-support system. Which means your goal ecosystem should be that ecosystem with as simple a macroscopic ecosystem as you can get away with.

My point was that the initial ecosystem you set up can't be the same as the one in the closed-loop system, because your closed-loop system relies on the initial presence of things like oxygen and nutrient solutions (i.e. soil) that don't necessarily exist on the planet. As for the goal ecosystem, if you're going to bother to do it at all, you'll eventually want the result to be more than merely "habitable" to humans. Your proposed aquatic environment could work -- a shallow freshwater aquatic ecosystem could provide everything you need with (presumably) less requirements for insect pollination and soil building, and would be ready sooner than a land-based agrarian lifestyle could be.

The smart thing to have done would've been to dispatch your machine intelligence and the seeds for a basic ecosystem aboard something capable of moving at something really fast. That way, most of the groundwork would've been completed by the time your slowship arrives

Well sure, but that doesn't seem to be in the OP. Ideally (and if you've got a lot of time) you'd send out a bunch of machine intelligences out to various candidate systems and then wait to see which ones are working best before heading out. Sending everyone out at once is risky, and really only the sort of thing you'd want to do if something was going Horribly Wrong on your homeworld.

Of course, if you're bringing everything aboard one ship, your decision whether or not to keep the colonists on ice will depend on how long the warranty on those cryopods or digital storage media is.

If you're thawing them out early, why stick them in a habitat on the surface? It'd probably be safer to build a closed-loop ecosystem inside a hollowed-out asteroid and establish your first colony there while you wait. That way, by the time the planet becomes viable, you'd conceivably be able to drop a population of thousands on it in numerous self-sustaining settlements.

The primary reason you'd thaw them early is because you need their work on the surface. The idea of having machine intelligences was an "add" to the scenario, and wouldn't necessarily be available. If you have machine intelligences and ship the industrial capacity for them to build robotic laborers (which you obviously would), then use them for all the work and thaw the humans only as needed. Even if you don't need their labor, if you have to thaw the humans early, I'd think you'd want to put them on the surface so they can be acclimatized to gravity, so they can use the protection of the planet's magnetic field from stellar radiation, and so they can expand their habitat as required without running out of space.

Horses. It is going to be quite some time before your colony is going to be in a position to build tractors, cars, and trucks. Horses will provide the ability to fill that gap.

It's going to be a long time before you can use horses, either. You'll need to be able to provide their oxygen requirements on the surface for millennia before they're any use. It's more than worth it to ship your colonists with at least some industrial capacity so that they can build and expand their habitat on site. It can serve double-duty for building vehicles if you need them. But if you're going the aquatic route, then you'd just build small boats anyway.

[GrandMasterTerwynn]

If you intend to terraform the planet, you're going to go through a long period of time where the surface isn't habitable while it makes the transition. You'll need not only the species you need for your "goal ecosystem," but also the species you'd need to help you terraform the planet in the first place -- you'll need oxygen creating bacteria, all the various species that will build your soil, and plenty of non-food plants.

Your terraforming ecosystem ought to be the same as the one in your ship's closed-loop life-support system. Which means your goal ecosystem should be that ecosystem with as simple a macroscopic ecosystem as you can get away with.

My point was that the initial ecosystem you set up can't be the same as the one in the closed-loop system, because your closed-loop system relies on the initial presence of things like oxygen and nutrient solutions (i.e. soil) that don't necessarily exist on the planet.

I'm assuming the basic closed-loop life-support system will feature a combination of unicellular life. We're not going to drop the macroscopic ecosystem we're going to stick in the habitat the colonists will be living in while they prepare the planet. By carefully selecting your strains of algae and bacteria, you ought to easily find something that will colonize the planet in relatively no time at all. This assumes that the planet is in condition to be terraformed without a multi-kiloyear effort to bring it up to the point where it can be.

As for the goal ecosystem, if you're going to bother to do it at all, you'll eventually want the result to be more than merely "habitable" to humans. Your proposed aquatic environment could work -- a shallow freshwater aquatic ecosystem could provide everything you need with (presumably) less requirements for insect pollination and soil building, and would be ready sooner than a land-based agrarian lifestyle could be.

That was my goal. Shallow freshwater ecosystems ought to be the environmental equivalent of low-hanging fruit. And you could pepper the planet with them. They'll also produce organic-rich silt which you could use as the basis of soil to begin the establishment of hardy conifer forests, as well as the planting of non insect-pollinated crops.

The smart thing to have done would've been to dispatch your machine intelligence and the seeds for a basic ecosystem aboard something capable of moving at something really fast. That way, most of the groundwork would've been completed by the time your slowship arrives

Well sure, but that doesn't seem to be in the OP. Ideally (and if you've got a lot of time) you'd send out a bunch of machine intelligences out to various candidate systems and then wait to see which ones are working best before heading out. Sending everyone out at once is risky, and really only the sort of thing you'd want to do if something was going Horribly Wrong on your homeworld.

By the time we've got the energy-production problems, and the multi-century equipment warranty problems licked, we ought to have gigantic interferometer arrays capable of directly imaging candidate planets. We'll be able to determine their ages, their masses, their atmospheric compositions, and may be able to generate crude maps of their surfaces. We'll know about how fast they rotate, if they've got any moons large enough to be imaged, and (roughly) how the planet will change through its local year. And we'll be certain that our intelligence is no more than a few decades out of date, since we'd not want to send colony ship further out than a few tens of light-years. We'll probably have a short list of candidates that have been under observation for decades or centuries before we could afford to even send out our first interstellar flyby probes.

Of course, if you're bringing everything aboard one ship, your decision whether or not to keep the colonists on ice will depend on how long the warranty on those cryopods or digital storage media is.

If you're thawing them out early, why stick them in a habitat on the surface? It'd probably be safer to build a closed-loop ecosystem inside a hollowed-out asteroid and establish your first colony there while you wait. That way, by the time the planet becomes viable, you'd conceivably be able to drop a population of thousands on it in numerous self-sustaining settlements.

The primary reason you'd thaw them early is because you need their work on the surface. The idea of having machine intelligences was an "add" to the scenario, and wouldn't necessarily be available.

If you've got the ability to build a starship that can ferry humans to another starsystem, and the automatic repair equipment necessary to keep the ship from exploding before reaching the system, or the molecular repair systems capable of fixing the cosmic ray and radioactive decay damage the corpsicles will accumulate in their centuries of inactivity . . . you're going to have machine intelligences. You shouldn't need the humans to set foot on the surface at all, except to handle the aesthetic parts of the terraformation ("Y'know, we've got this mass-driver here, and that spit of land in the north is just begging to be sculpted into a copy of Norway . . .")

If you have machine intelligences and ship the industrial capacity for them to build robotic laborers (which you obviously would), then use them for all the work and thaw the humans only as needed. Even if you don't need their labor, if you have to thaw the humans early, I'd think you'd want to put them on the surface so they can be acclimatized to gravity

Why? Just adjust the spin-rate of the starship's habitat.

so they can use the protection of the planet's magnetic field from stellar radiation, and so they can expand their habitat as required without running out of space.

They've come aboard a starship capable of shielding them from centuries of cosmic rays, the radiation flux generated by plowing through the ISM at relativistic velocities, and the radiation flux generated by their own insanely-dangerous engines. They're also not apt to take this expensive ship and its very expensive cargo to a star that's going to obliterate them with a superflare. They're going to know how to build orbital habitats out of asteroids, and one of those ought to provide for their space needs for the duration of the terraforming effort.

Unless, of course, they're doing it for some bizarre religious reason that demands that humans live on planets.

Horses. It is going to be quite some time before your colony is going to be in a position to build tractors, cars, and trucks. Horses will provide the ability to fill that gap.

It's going to be a long time before you can use horses, either. You'll need to be able to provide their oxygen requirements on the surface for millennia before they're any use. It's more than worth it to ship your colonists with at least some industrial capacity so that they can build and expand their habitat on site. It can serve double-duty for building vehicles if you need them. But if you're going the aquatic route, then you'd just build small boats anyway.

Indeed. Horses are a stupid idea for the pioneering wave of interstellar colonization. They need lots of oxygen, and tons and tons of grain, given that they've got inefficient digestive systems. They've also got that small problem of requiring parenting, and of costing the cryopod space of up to ten humans per horse. The colony is going to have the ability to build vehicles from the get-go. If they don't, then something went Horribly Wrong, and the colony is going to be fucked anyway.

[Turin]

By carefully selecting your strains of algae and bacteria, you ought to easily find something that will colonize the planet in relatively no time at all. This assumes that the planet is in condition to be terraformed without a multi-kiloyear effort to bring it up to the point where it can be.

Is that even possible? A lot of what makes life as it currently exists on Earth possible is the prior work of previous species, which took many millions of years. If you have a place that's marginal but without native life, it's going to be missing key elements that are created by that native life. (This is the underlying assumption for a lot of the real-world search for life on other planets; life has a chemical fingerprint.) That makes for a big gulf in the effort required, and a place without native life isn't going to be terraformed in a short period of time.

Ideally (and if you've got a lot of time) you'd send out a bunch of machine intelligences out to various candidate systems and then wait to see which ones are working best before heading out. Sending everyone out at once is risky, and really only the sort of thing you'd want to do if something was going Horribly Wrong on your homeworld.

By the time we've got the energy-production problems, and the multi-century equipment warranty problems licked, we ought to have gigantic interferometer arrays capable of directly imaging candidate planets. <snip> We'll probably have a short list of candidates that have been under observation for decades or centuries before we could afford to even send out our first interstellar flyby probes.

By "which ones are working best" I meant which colonies are operating best by the time you set out. You'd have taken a good look at candidates first, but if we assume a non-zero chance of failure of any given colony (which seems obvious), you would have a couple of terraforming projects in the works so you'd have your pick of which one to use for your first live colony. Again, multiplying the effort involved but efficiency doesn't seem the primary motivation here.

The primary reason you'd thaw them early is because you need their work on the surface. The idea of having machine intelligences was an "add" to the scenario, and wouldn't necessarily be available.

If you've got the ability to build a starship that can ferry humans to another starsystem, and the automatic repair equipment necessary to keep the ship from exploding before reaching the system, or the molecular repair systems capable of fixing the cosmic ray and radioactive decay damage the corpsicles will accumulate in their centuries of inactivity . . . you're going to have machine intelligences.

How does that follow? Both you and Starglider are saying that's so, but I'm not seeing anything backing it up. I agree that it's likely, but I've already posted at least one scenario in which machine intelligences wouldn't be available (superstitious reasons). The trip itself requires an intelligence in the loop, but there's no particular reason that, if you're going through the trouble at all, those intelligences couldn't be humans who are thawed out for the duration of the trip.

They've come aboard a starship capable of shielding them from centuries of cosmic rays, the radiation flux generated by plowing through the ISM at relativistic velocities, and the radiation flux generated by their own insanely-dangerous engines. They're also not apt to take this expensive ship and its very expensive cargo to a star that's going to obliterate them with a superflare. They're going to know how to build orbital habitats out of asteroids, and one of those ought to provide for their space needs for the duration of the terraforming effort.

Clearly they could do this. I guess I was making an unspoken assumption that they'd need to use the ship's power source for the terraforming effort because of the mass involved in hauling it from across interstellar space. But if they can build everything on-site (using asteroid mining for raw materials), that's less of a problem.

Unless, of course, they're doing it for some bizarre religious reason that demands that humans live on planets.

Which, as I've posited earlier, seems more likely the case than not. The result doesn't justify the effort except for aesthetic or superstitious reasons.

[GrandMasterTerwynn]

By carefully selecting your strains of algae and bacteria, you ought to easily find something that will colonize the planet in relatively no time at all. This assumes that the planet is in condition to be terraformed without a multi-kiloyear effort to bring it up to the point where it can be.

Is that even possible?

Sure. A dead world suitable for terraforming, like a Mars-analogue would look much different than a world that is unsuitable for terraforming, like Venus or Mercury.

However, a sufficiently advanced civilization may find it to be no problem to hijack a local large asteroid as a gravity tug to drag a Mercury or a Venus out of their present orbits and into something more hospitable. And would have similarly minimal problems equipping either one with a suitable atmosphere. Or even constructing arrays of giant mirrors to render something Ganymede or Callisto roughly human-habitable. The scope of these projects, I assume, would be much greater than a first-wave interstellar colony would be willing to undertake.

A lot of what makes life as it currently exists on Earth possible is the prior work of previous species, which took many millions of years. If you have a place that's marginal but without native life, it's going to be missing key elements that are created by that native life. (This is the underlying assumption for a lot of the real-world search for life on other planets; life has a chemical fingerprint.) That makes for a big gulf in the effort required, and a place without native life isn't going to be terraformed in a short period of time.

However, for best terraforming results, you don't want a planet whose local life has evolved much beyond the level of stromalites. That way, you can supplant the preexisting primitive ecology with your own human-compatible one. If you find a planet full of macroscopic life with mature ecosystems with almost certainly incompatible biochemistry, you'll be better off planetforming the colonists, rather than terraforming the planet. Fortunately, given how long the former ecology dominated Earth, versus the latter, you're probably guaranteed to have your pick of minimally inhabited planets.

The primary reason you'd thaw them early is because you need their work on the surface. The idea of having machine intelligences was an "add" to the scenario, and wouldn't necessarily be available.

If you've got the ability to build a starship that can ferry humans to another starsystem, and the automatic repair equipment necessary to keep the ship from exploding before reaching the system, or the molecular repair systems capable of fixing the cosmic ray and radioactive decay damage the corpsicles will accumulate in their centuries of inactivity . . . you're going to have machine intelligences.

How does that follow? Both you and Starglider are saying that's so, but I'm not seeing anything backing it up. I agree that it's likely, but I've already posted at least one scenario in which machine intelligences wouldn't be available (superstitious reasons).

Simple. Barring some bizarre-o physics out of left field which make handwavium drives possible, a human-occupied starship is going to take centuries just to get to where it's going. A starship isn't the Great Pyramid, which is to say, it's not going to last very long without maintenance. Which means you're going to need something capable of operating for decades or centuries which will be capable of looking after all the complex systems of a starship, managing the course corrections needed to keep the ship pointed at its distant goal, and to get it to where it is going without overshooting the target by some fraction of c. This is going to require quite a collection of expert systems to manage all of that complexity. And these systems are going to have to know how to fix themselves, should something go wrong. The best solution for this would be an advanced machine intelligence. If one were to insist on not using machine intelligences, that leaves one of three possibilities:

A) Select members of the crew being thawed out in shifts.
B) Genetically engineered superhumans with extremely long lifespans.
C) Generation ship.

While you could use option A, this means you're burning fuel to keep the life-support systems up. And subjecting crewmembers to the wear and tear of repeated wake-sleep-freeze-defrost cycles. While they're awake, they're going to age. Potentially acceptable, if a given shift only needs to be awake for one or two months out of the year, the ship isn't going all that far, and you've advanced cryo-technology to the point where you're not liable to kill the crew by doing this.

Options B and C have their own unique set of problems.

They've come aboard a starship capable of shielding them from centuries of cosmic rays, the radiation flux generated by plowing through the ISM at relativistic velocities, and the radiation flux generated by their own insanely-dangerous engines. They're also not apt to take this expensive ship and its very expensive cargo to a star that's going to obliterate them with a superflare. They're going to know how to build orbital habitats out of asteroids, and one of those ought to provide for their space needs for the duration of the terraforming effort.

Clearly they could do this. I guess I was making an unspoken assumption that they'd need to use the ship's power source for the terraforming effort because of the mass involved in hauling it from across interstellar space. But if they can build everything on-site (using asteroid mining for raw materials), that's less of a problem.

The problem of hauling all that mass across interstellar space will probably limit the fuel they will carry. They will carry just enough to get them where they are going. To reduce this, they'll probably use some sort of antimatter-catalyzed fusion, or a straight antimatter rocket. After they get there, the first thing they'll be doing is fabricating solar arrays, or a fusion reactor that doesn't require antimatter for its operation.

[Turin]

Sorry I let this drop off my radar for a couple days...

By carefully selecting your strains of algae and bacteria, you ought to easily find something that will colonize the planet in relatively no time at all. This assumes that the planet is in condition to be terraformed without a multi-kiloyear effort to bring it up to the point where it can be.

Is that even possible?

Sure. A dead world suitable for terraforming, like a Mars-analogue would look much different than a world that is unsuitable for terraforming, like Venus or Mercury. However, a sufficiently advanced civilization may find it to be no problem to hijack a local large asteroid as a gravity tug to drag a Mercury or a Venus out of their present orbits and into something more hospitable.

It's not just about being in the hospitable zone, however (see my next point).

A lot of what makes life as it currently exists on Earth possible is the prior work of previous species, which took many millions of years. If you have a place that's marginal but without native life, it's going to be missing key elements that are created by that native life. (This is the underlying assumption for a lot of the real-world search for life on other planets; life has a chemical fingerprint.) That makes for a big gulf in the effort required, and a place without native life isn't going to be terraformed in a short period of time.

However, for best terraforming results, you don't want a planet whose local life has evolved much beyond the level of stromalites. That way, you can supplant the preexisting primitive ecology with your own human-compatible one. If you find a planet full of macroscopic life with mature ecosystems with almost certainly incompatible biochemistry, you'll be better off planetforming the colonists, rather than terraforming the planet. Fortunately, given how long the former ecology dominated Earth, versus the latter, you're probably guaranteed to have your pick of minimally inhabited planets.

I think you missed my point slightly. You don't need (or indeed even want, as you point out) an existing ecosystem of highly evolved macroscale organisms. But the only way you can have a "short" terraforming project is if you've got an existing ecosystem of microscopic organisms there to create a reasonably comfortable atmosphere ahead of time. Otherwise you've got to build that from scratch as well, which in the case of something like Mars means adding or freeing up a few petatons of mass. There's a big difference between a Venus and a Mars, as you say, but there's also a difference (although not as monumental) between a Mars and an "Early Earth"-equivalent. The latter is going to be far easier than the former, and more desirable for a first colony.

If you've got the ability to build a starship that can ferry humans to another starsystem, and the automatic repair equipment necessary to keep the ship from exploding before reaching the system, or the molecular repair systems capable of fixing the cosmic ray and radioactive decay damage the corpsicles will accumulate in their centuries of inactivity . . . you're going to have machine intelligences.

How does that follow? Both you and Starglider are saying that's so, but I'm not seeing anything backing it up. I agree that it's likely, but I've already posted at least one scenario in which machine intelligences wouldn't be available (superstitious reasons).

Simple. Barring some bizarre-o physics out of left field which make handwavium drives possible, a human-occupied starship is going to take centuries just to get to where it's going. A starship isn't the Great Pyramid, which is to say, it's not going to last very long without maintenance. Which means you're going to need something capable of operating for decades or centuries which will be capable of looking after all the complex systems of a starship, managing the course corrections needed to keep the ship pointed at its distant goal, and to get it to where it is going without overshooting the target by some fraction of c. This is going to require quite a collection of expert systems to manage all of that complexity. And these systems are going to have to know how to fix themselves, should something go wrong. The best solution for this would be an advanced machine intelligence. If one were to insist on not using machine intelligences, that leaves one of three possibilities:

A) Select members of the crew being thawed out in shifts.
B) Genetically engineered superhumans with extremely long lifespans.
C) Generation ship.

While you could use option A, this means you're burning fuel to keep the life-support systems up. And subjecting crewmembers to the wear and tear of repeated wake-sleep-freeze-defrost cycles. While they're awake, they're going to age. Potentially acceptable, if a given shift only needs to be awake for one or two months out of the year, the ship isn't going all that far, and you've advanced cryo-technology to the point where you're not liable to kill the crew by doing this.

Options B and C have their own unique set of problems.

I don't disagree whatsoever that having a machine intelligence in charge during the trip is a better solution. My point was it still doesn't follow that one will be available. If your civilization hasn't invented AGI, you might be stuck with having to go with another less desirable option (like a generation ship wherein a smallish number of crew are active while the bulk of the human cargo remains frozen).

[Junghalli]

The easiest planet to terraform (if you would consider it terraforming, as you're not really changing the environment) is a place like Cambrian Earth. It already has an oxygen atmosphere, but the continents are still barren, so you can just introduce an Earthly terrestrial ecology to fill them up.

After that the best is a planet like primordial Earth. You just introduce some fast-working photosynthetic organisms to oxygenate the atmosphere, and then introduce whatever terrestrial and marine organisms you want.

After that the next best is something like a snowball Earth, which doesn't have Earthlike conditions but it's fairly easy to kick the environment over to something friendly. To terraform a snowball you just have to pump tons of greenhouse gas into the atmosphere to warm it up, then repeat the steps you'd use on a primordial atmosphere planet.

After that you have the real "fixer uppers" like Mars.

After that you have planets like Venus, which probably aren't really worth it.