An O'Neill cylinder large enough to house a self-sustaining ecosystem during a mission to nearby candidate star systems with potentially exploitable/colonisable planetary systems.
O'Neill cylinder is not designed to support propulsion.
Thanks for the speedy reply. I had not really considered deeply the purpose of the mission.For the back-story here I guess we would be thinking in terms of the cylinder being used to 'seed' other planets. Because a cylinder, no matter how well made, is potentially very fragile and prone to accidents. If the purpose of the mission were to propagate humanity then I would expect it to colonise any terraformable planets it encountered on an indefinitely long mission, simply to increase long-term survival chances for somebody at least.
Destination:Anywhere. If a civilization has the in-space industrial capabilities to build an O'Niell cylinder then it has no need for planets. Asteroids are much easier to extract materials from to construct more colonies. Teraforming is way harder, and still yields sharply limited living space.Only interest in planets would be scientific - looking for life etc.
If you want "realism" - calculate the transit time to, say, Alpha Centauri at, say, 20 kilometers per second, roughly 2 trillion seconds, or around 64,500 years. 20 kps is about 20% faster than the New Horizons probe presently on its way to Pluto, by way of comparison.
Quote from: Eer on 01/25/2013 06:58 pmIf you want "realism" - calculate the transit time to, say, Alpha Centauri at, say, 20 kilometers per second, roughly 2 trillion seconds, or around 64,500 years. 20 kps is about 20% faster than the New Horizons probe presently on its way to Pluto, by way of comparison.New Horizons was a chemical mission. We could do much better with a very little development using solar or nuclear electric propulsion, and better still with near-term hard-sci-fi options like fission fragment rockets or aneutronic directed fusion product drives. Realism doesn't mean a modest extrapolation of past achievements; it means a modest extrapolation of existing technology.You could use nuclear pulse propulsion, but you'd have to be careful to keep the thrust level down and/or engineer your habitat to work in two axes...
The traditional approach is to fit the inertial confinement fusion system suggested for the BIS Daedalus interstellar probe to your interstellar ark, this gets you to maybe 1-3% the speed of light, you then head off to Epsilon Eridani which at 10.5 LY distance will take from 350 to 1000 years to get to. Or maybe you could wait another century before leaving, pick the closer Alpha Centauri (as James Cameron did) and use light sails and antimatter annihilation to get to your destination way quicker (as James Cameron did). http://www.projectrho.com/public_html/rocket/realdesigns.php
Thanks for the food for thought so far, guys. I guess that the point is well taken about there being little need to colonise other systems when our own could be exploited far better using the kind of technology I am asking for.Let's say, instead, as it is not too important to the main thrust of the plot WHY the mission is happening, that we were 'invited' to go visit [name of local, possibly viable for life system here].Any thoughts on light and internal power sources? I like the idea of a central 'tube' of some kind of plasma that provides heat and light. Could anyone think of a mechanism for this, coupled, maybe, with a propulsion system?
One of the things that concerns me is the amount of fuel required. Are there any currently proposed forms of propulsion where there is no necessity for carry large amounts of fuel to propel a cylinder potentially of many millions of tons?