Generation vs Colony vs Cryo

penny wrote:What are the major differences in the various ship designations?

It was discovered early in the Diaspora that the maximum practical safe speed for a sublight ship was approximately .8 c, as radiation and particle shields can not protect the vessel above that velocity.

The generation ships were built as complete, life-sustaining habitats oriented around the smallest practical self-sustaining population and designed to boost to that velocity at one gravity. In the long term, onboard gravity was provided through centrifugal force. In addition to their human passengers, the generation ships also had to provide for all terrestrial livestock and plants which would be required to terraform the colonists' new home for their survival. Even aboard these huge ships, space was severely limited, and many early colonial expeditions reached their destinations only to come to grief through the lack of some essential commodity the settlers had not known to bring along. This sort of disaster became less common after about 800 pd, when the original, crude hyperships made it possible to conduct extensive surveys of potential colony sites before the slower colony ships departed, but by that time the generation ships were a thing of the past, anyway.

In 305 pd, cryogenic hibernation finally became practical. It had long been possible to cryogenically preserve limbs and organs, though even the best anti-crystallization procedures then available were unable to prevent some damage to the preserved tissues. But where minor damage to an arm or a liver was acceptable, damage to a brain was not, and the early cryogenic pioneers' enthusiastic predictions about indefinite suspension of the life processes had proven chimerical.

It was Doctor Cadwaller Pineau of Tulane University who, in 305, finally cut the Gordian knot of cryogenic hibernation by going around the crystallization problem. He found that by lowering the hibernator's temperature to just barely above the freezing point he could maintain the physiological processes indefinitely at about a 1:100 time ratio. In other words, a hibernating human would age approximately one year for every century of hibernation, and his nutritional and oxygen requirements were reduced proportionately. Over the next several decades, Pineau and his associates further refined his process, working to overcome the problem of muscular atrophy and other physiological difficulties associated with long comatose periods, and eventually determined that optimum results required a hibernating individual to rouse and exercise for approximately one month in every sixty years (ie., after six physiological months), which remained a fixed requirement throughout the cryogenic colonization era.

What this meant was that the life support capabilities of a cryo ship could be vastly reduced in comparison to those of a generation ship. Moving at .8 c, the colonists experienced a 60% time dilation effect; in other words, each sixty-year period of hibernation used up one century of voyage time by the standards of the remainder of the universe. Thus an entire one-century voyage could be made without a single "active" period and would consume only 7.2 apparent months of the traveler's life span. Longer voyages would require periodic awakenings, but they could be staggered, permitting the currently roused crew to use only a fraction of the life support the entire crew would require. The result was to permit far larger numbers of colonists to travel on a given sized ship with a far lower subjective time passage.

penny wrote:What are the major differences in the various ship designations?

Jonathan_S wrote:And so because the trip to the colony planet exceeds human lifespan it is the descendants of the original settlers who arrive on the colony world. Usually several generations later, so it might be the great, great, grandchildren of the original colonists who are running the ship when it finally arrives.

A Cryo ship has all the settlers, and probably most of the crew, is cryogenic suspension for the entire trip. You'd have a relatively small caretaker/maintenance crew awake at any given time. In theory the crew could be generational but more likely you'd bring extra crew and rotate them in and out of cryo so you don't need to worry about training replacements mid-flight. But nowever the crew is managed it's the original colonists who are woken up to settle the new word -- having slept through the entire multi-century journey.

(And eventually safe hyper-capable transport made both obsolete because now colonists could be moved to their new world in a mater of months, not centuries)

penny wrote:Thanks for the info tlb! I will not get access over the holiday season.

I am still a bit confused. Jonathan's post took care of my immediate questions about colony ships, which seems to be lacking from your posted text. Thanks Jonathan.

It seems that I was wrong about either designation not being essentially space-faring Noah's Arks. The generation ships did stock at least two of every animal that they wanted. Probably more to be capable of ensuring both the survival of the livestock and to simultaneously feed the colonists. A generation ship appears to have been a huge behemoth compared to later designs. Does the text give the size comparisons of each design? A generation ship gives me the impression that it is larger than a fort!

And also, does the text give the population of each ship? The generation ship would have a huge population at the end of its trip than at the start, obviously. So, it has to have stocked much more water than any other ship. And their water supply has to serve the people, the animals and the gardens as well. Generation ships have the capacity to store a lot of water for the duration of such an extended trip. What an immense capacity of water for people, livestocks and plants to consume over such a long trip. Which is how long exactly for a generation ship? It has been posited in the forum that there might be generation ships that still have not reached their destination.

So, lingering questions:

1. Size of the ships comparatively.

2. Method of propulsion.

3. Length of trip.

4. Population.

Jonathan_S wrote:And so because the trip to the colony planet exceeds human lifespan it is the descendants of the original settlers who arrive on the colony world. Usually several generations later, so it might be the great, great, grandchildren of the original colonists who are running the ship when it finally arrives.

ThinksMarkedly wrote:And it's entirely possible that a great deal of those who finally arrive want no part in living on the surface of a planet. They may develop acute agoraphobia or be sick from the lack of Coriolis force (no spin gravity). Or they simply don't want, because they have always lived on a ship, that's all they've known, all the people they've known had known.

Given this is a possibility, it's even the more reason that the planning of the expedition should take into account the ability to completely duplicate their ship at a reasonable star system. Some people will want to stay, some will want to continue the journey, so you allow for both options.

tlb wrote:

Jonathan_S wrote:And so because the trip to the colony planet exceeds human lifespan it is the descendants of the original settlers who arrive on the colony world. Usually several generations later, so it might be the great, great, grandchildren of the original colonists who are running the ship when it finally arrives.

ThinksMarkedly wrote:And it's entirely possible that a great deal of those who finally arrive want no part in living on the surface of a planet. They may develop acute agoraphobia or be sick from the lack of Coriolis force (no spin gravity). Or they simply don't want, because they have always lived on a ship, that's all they've known, all the people they've known had known.

Given this is a possibility, it's even the more reason that the planning of the expedition should take into account the ability to completely duplicate their ship at a reasonable star system. Some people will want to stay, some will want to continue the journey, so you allow for both options.

I doubt that any colony ship ever allowed for the complete duplication of a ship. For one thing, why would your assumed section of population that do not want to live on the ground decide to fly away? Why not continue to live in an orbital and remain in contact with their fellow colonists? If I remember correctly, Calvin's Hope remained intact.

For another, any manufacturing ability on the original ship would have been designed to build things for life on the planet. Since space is limited, I consider it unlikely there is the capacity for anything too large.

penny wrote:It seems that I was wrong about either designation not being essentially space-faring Noah's Arks. The generation ships did stock at least two of every animal that they wanted. Probably more to be capable of ensuring both the survival of the livestock and to simultaneously feed the colonists.

penny wrote:And also, does the text give the population of each ship? The generation ship would have a huge population at the end of its trip than at the start, obviously. So, it has to have stocked much more water than any other ship. And their water supply has to serve the people, the animals and the gardens as well. Generation ships have the capacity to store a lot of water for the duration of such an extended trip. What an immense capacity of water for people, livestocks and plants to consume over such a long trip. Which is how long exactly for a generation ship? It has been posited in the forum that there might be generation ships that still have not reached their destination.