Ah ok i see where i made a mistake. I dont see why one should use an ICE, Alcohol fuelcells (heck there are Diesel fuelcells that are 60% efficient) seem to be a better choice.
That could work too. I'm not an expert in space power systems.
I wouldnt be surprised if your Photovoltaics have to be cooled as well somehow althought they could work as theyr own radiator. Only around 20% of the sunlight gets turned into Electric power so you have to deal with 80% that remain. Part of it will be reflected but another will just heat your pannels up.
The RTGs where just an example for backup power. You could also burn fuel (like the ethanol from your Horse / ICE discussion) as well as disolve Ammonia or caustic soda in water or whatever you like. Heck you could use the heat from composting your biodegradable waste. I agree thought that RTGs are more suited for Main Powersuply - they were a rather bad example.
Depending on how far i am from the star i would anyway switch from one form of power generation to another. For once i would use Solarwind power if i am in the inner parts of the system since catching electrons (and ions) form the solar wind needs only a antenna and some tinfoil. On the outskirts thought i would prefer to have trusty RTG or Traveling wave reactor althought i am normaly against fission reactors.
Backup power supply would probably be batteries. I'd imagine that the RTG and whatever thermal generator it has are well-matched.
And I'm under the impression that solar panels serve as their own radiators.
Solar wind power? I'd never heard of it, and despite a little bit of research, I'm still not sure exactly how it works.
The problem with proposing multiple power systems is mass efficiency. If a given system has enough power, then don't bother with anything else, particularly given that your power requirements will stay static or increase as you move away from the sun.
I would argue using water for the reaction mass would be logistically better.
Yes, I know it doesn't work as well since it ties up more energy in intermolecular bonds instead of speed (and hence efficiency is lower) But water ice is semi-plentiful in systems. With a high density energy source like AM or nuclear fusion, a fleet tanker could pack ice mining equipment and refuel reaction mass from asteroids.
If you have DD fusion or even HH fusion, water ice contains your fusion power source as well!
If you are feeling adventurous, hydrogen might be an option as well. Scoop from gas giants sounds like a recipe for Fun though. Swing into a massive gravity well to scoop hydrogen from a gas giant while relying on your speed to get back out (and scooping will put drag on your ship... ^^)
I really, really doubt that water would be a good choice for ion thrusters. Most of the ones I've looked at use noble gasses, which are far less reactive then water. For a thermal engine, on the other hand, it's a very viable option. The only qualm I have is that hydrogen might be too valuable, but in that case LOX is a good second choice.
And I really, really doubt we'll ever see D-D fusion as a power source. He3-D and D-T are much more practical. Take everything above to the 20th power for H-H.
They are catching up!
http://www.bbc.co.uk/news/science-environment-17855194
On the whole organics thing I do like Peter Hamilton's take on it in his Night's Dawn(?) trilogy. Seeding a ship and leaving it grow itself in the atmosphere of a gas giant might take time but not needed any infrastructure and being able to grow 100s at once isn't a bad trade off in my books. I seem to recollect that the ships then had weapon pods etc just bolted onto them which solves alot of the whole organic solution for everything issue.
How does a pigeon being able to detect magnetic fields help make living spacecraft? That's not a terribly difficult thing to do, nor does it require high energy.
Grow in the atmosphere of a gas giant? What's it made out of? Metallic hydrogen?
As for bolting on the high-tech bits, sure, it's possible. But why? Generally, those are the pacing items in ship construction. An organic hull really isn't really that big of a cost-saver. Also, the self-repair ability is very limited, given that all the gadgets must be replaced.
