You should pick up a copy of GURPS Space and possibly Ultra Tech. The Space book is basically a scenario and genre planner that would be very, very useful for fantasy writers. Several physicists, published authors, biologists of various stripes, etc participated in the playtest (and yours truly from a "keep it story focused, not science focused" angle). The concept of generation ships is discussed, and many other types.
There's another book out there called, um...Revelation Space, perhaps? That had a virtual generation ship, which was interesting.
Anyway, I'd think that for a true generation/colony ship, you'd up the crew by 100x...fifty thousand souls, in a ship probably made by hollowing out an asteroid or something. Over a long-term occupation, you'd want all that mass for cosmic ray protection, esp if you're using some non-physics based drive to accelerate up to a significant fraction of light-speed. you'd want the population reasonably large, in order to ensure that any accidents don't reduce your crew below the survivability threshold, and also for genetic diversity.
Alternately, the core of the ship could contain the genetic divesity, with a cargo of cryogenically frozen embryos. In that case, crew could legitimately be in the thousands.
As an FYI, the crew of a modern attack submarine which can stay at sea for 90 days (limited by food, not power or oxygen) is about 120 souls, costs a billion dollars, is about 100m long, 10m across, and masses about 7,000,000 kg (7000 metric tons).
So, if we treat the ship as a big block, it's about 10,000 cubic meters, giving it a density of 0.7 tons per cubic meter (less than water, which is why it needs the ballast tanks). That's also about 80 cubic meters per person, so a crew of 50,000 active people might require 4 million cubic meters, or (assuming the same dimensions as the sub) it would be about fifty meters wide and two kilometers long. It doesn't need to be so streamlined, though...it could easily be more squat, say a cylinder with only a 3:1 aspect ratio, giving 110m diameter and 330m long...but now you may want to consider spinning it for gravity, which means you're really dealing with only the INNER part of it, maybe in a couple layers/floors.
Can you tell I took a class on space colonies in college?
Anyway, I know there are a ton of resources out there on generation ships, etc. I believe "Rendevous with Rama" was about a generation ship, possibly a sentient one (?).
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regna
(no subject)
Date: 2008-05-15 02:46 am (UTC)There's another book out there called, um...Revelation Space, perhaps? That had a virtual generation ship, which was interesting.
Anyway, I'd think that for a true generation/colony ship, you'd up the crew by 100x...fifty thousand souls, in a ship probably made by hollowing out an asteroid or something. Over a long-term occupation, you'd want all that mass for cosmic ray protection, esp if you're using some non-physics based drive to accelerate up to a significant fraction of light-speed. you'd want the population reasonably large, in order to ensure that any accidents don't reduce your crew below the survivability threshold, and also for genetic diversity.
Alternately, the core of the ship could contain the genetic divesity, with a cargo of cryogenically frozen embryos. In that case, crew could legitimately be in the thousands.
As an FYI, the crew of a modern attack submarine which can stay at sea for 90 days (limited by food, not power or oxygen) is about 120 souls, costs a billion dollars, is about 100m long, 10m across, and masses about 7,000,000 kg (7000 metric tons).
So, if we treat the ship as a big block, it's about 10,000 cubic meters, giving it a density of 0.7 tons per cubic meter (less than water, which is why it needs the ballast tanks). That's also about 80 cubic meters per person, so a crew of 50,000 active people might require 4 million cubic meters, or (assuming the same dimensions as the sub) it would be about fifty meters wide and two kilometers long. It doesn't need to be so streamlined, though...it could easily be more squat, say a cylinder with only a 3:1 aspect ratio, giving 110m diameter and 330m long...but now you may want to consider spinning it for gravity, which means you're really dealing with only the INNER part of it, maybe in a couple layers/floors.
Can you tell I took a class on space colonies in college?
Anyway, I know there are a ton of resources out there on generation ships, etc. I believe "Rendevous with Rama" was about a generation ship, possibly a sentient one (?).