09-20-2014, 11:42 PM
I would disagree on several fronts:
a) For interstellar travel in any kind of 'reasonable' time frame to work at all you are talking about fielding energies hundreds to tens of thousands of times the output of our entire civilization. The more so if you are actually going to do an actual colonization mission. The amount of fuel required to power the ship as a type of space colony in its own right (rather than a propelled vessel) would be minimal in comparison - even if you wanted enough to run it for years or decades just on internal sources.
b) Using mag-braking as Zubrin has suggested a colony ship could slow down with essentially zero fuel expenditure (except for the last bit of the trip). This takes longer with the slower ships early in the timeline, but they are slower anyway, so I'm not sure it makes that much difference. Regardless, use of magbraking should greatly reduce the amount of fuel required for decel and thus free up a margin for use for energy when the ship arrives.
c) It isn't correct as a blanket statement to say that the power is in the inner system while the volatiles are in the outer. The Earth is in the inner system and gets plenty of solar energy and has plenty of volatiles. In addition, if you have a fusion drive and a colony ship, then you can just go to the outer system and extract fusion fuel from the volatiles there - no need to bother with the inner system for that - although you may (or may not) need to send mining expeditions around for raw materials (depends on the composition of the bodies in the outer system).
Conversely, you could put the ship in orbit in the inner system and use solar energy and then send out mining expeditions to volatiles sources in the outer system if your energy tech is more slanted that way.
d) Unless your colony is of minimal mass, it will have various secondary craft that could be sent out to extract resources from different locations in the system as well as the experience of industrial scale resource extraction in the solar system - as such the miners should have a good idea of where to find what. Possibly precursor probes would have already surveyed the system thoroughly and located useful concentrations of resources before the expedition ever arrives - the entire notion of colonists simply arriving in a new solar system with no idea of what they will find and no preparation owes more to the colonization of the Americas and the American West (and a heavy dose of romanticism) than any realistic assessment of how an interstellar capable civilization (even an early one) would go about colonizing a new solar system.
To provide a point of comparison - imagine what would happen if a new continent suddenly appeared in the middle of one of the oceans and our civilization decided to set up colonies there. We certainly wouldn't do it the way the first English or Spanish colonials did it. We would use satellites, recon flights, both manned and drones, and the experience of decades to a century of resource location techniques as part of the process. At least that level of tech is likely to be employed with a colony.
e) In OA we presume that nanotech and neumann technology come along fairly early in the timeline, along with advanced robotics in various forms. By the time of the ND, neumanns could apparently replicate on timescales of a year or less. Far faster than what Freitas describes (I agree it might be interesting to use his article as a resource to inform an updated Neumann article - but we also need to take into account tech that he doesn't in this paper and that we already include in the setting) and therefore able to accomplish far more than what he describes here. We also make mention of some issues with self-rep tech that is too long unsupervised in OA, and that also would need to be taken into consideration - but that also makes a place for adventures and stories of various sorts.
The upshot of all this is that I would argue that by the time we have the means to launch interstellar colonies, we also will have the means to bypass the sort of bottlenecks described here - as well as take an approach to colonization that is quite different from that normally depicted in SF, which itself is based on ideas of colonization that are centuries out of date.
My 2c worth,
Todd
a) For interstellar travel in any kind of 'reasonable' time frame to work at all you are talking about fielding energies hundreds to tens of thousands of times the output of our entire civilization. The more so if you are actually going to do an actual colonization mission. The amount of fuel required to power the ship as a type of space colony in its own right (rather than a propelled vessel) would be minimal in comparison - even if you wanted enough to run it for years or decades just on internal sources.
b) Using mag-braking as Zubrin has suggested a colony ship could slow down with essentially zero fuel expenditure (except for the last bit of the trip). This takes longer with the slower ships early in the timeline, but they are slower anyway, so I'm not sure it makes that much difference. Regardless, use of magbraking should greatly reduce the amount of fuel required for decel and thus free up a margin for use for energy when the ship arrives.
c) It isn't correct as a blanket statement to say that the power is in the inner system while the volatiles are in the outer. The Earth is in the inner system and gets plenty of solar energy and has plenty of volatiles. In addition, if you have a fusion drive and a colony ship, then you can just go to the outer system and extract fusion fuel from the volatiles there - no need to bother with the inner system for that - although you may (or may not) need to send mining expeditions around for raw materials (depends on the composition of the bodies in the outer system).
Conversely, you could put the ship in orbit in the inner system and use solar energy and then send out mining expeditions to volatiles sources in the outer system if your energy tech is more slanted that way.
d) Unless your colony is of minimal mass, it will have various secondary craft that could be sent out to extract resources from different locations in the system as well as the experience of industrial scale resource extraction in the solar system - as such the miners should have a good idea of where to find what. Possibly precursor probes would have already surveyed the system thoroughly and located useful concentrations of resources before the expedition ever arrives - the entire notion of colonists simply arriving in a new solar system with no idea of what they will find and no preparation owes more to the colonization of the Americas and the American West (and a heavy dose of romanticism) than any realistic assessment of how an interstellar capable civilization (even an early one) would go about colonizing a new solar system.
To provide a point of comparison - imagine what would happen if a new continent suddenly appeared in the middle of one of the oceans and our civilization decided to set up colonies there. We certainly wouldn't do it the way the first English or Spanish colonials did it. We would use satellites, recon flights, both manned and drones, and the experience of decades to a century of resource location techniques as part of the process. At least that level of tech is likely to be employed with a colony.
e) In OA we presume that nanotech and neumann technology come along fairly early in the timeline, along with advanced robotics in various forms. By the time of the ND, neumanns could apparently replicate on timescales of a year or less. Far faster than what Freitas describes (I agree it might be interesting to use his article as a resource to inform an updated Neumann article - but we also need to take into account tech that he doesn't in this paper and that we already include in the setting) and therefore able to accomplish far more than what he describes here. We also make mention of some issues with self-rep tech that is too long unsupervised in OA, and that also would need to be taken into consideration - but that also makes a place for adventures and stories of various sorts.
The upshot of all this is that I would argue that by the time we have the means to launch interstellar colonies, we also will have the means to bypass the sort of bottlenecks described here - as well as take an approach to colonization that is quite different from that normally depicted in SF, which itself is based on ideas of colonization that are centuries out of date.
My 2c worth,
Todd