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Re: starship-design: scoops and sails and something to push against.

Hi Group

Steve VanDevender wrote:

> KellySt@aol.com writes:
>  > This runs into the two big questions:
>  >  - Who'ld pay for all this?
>  >  - Why?
>  >
>  > We could never figure out why anyone would fund a exploration leval missino.
>  > a migratino through the galaxy mission is really over the top.
> With our current level of technology and planet-bound economy, I
> can see how it would be hard to imagine how to fund interstellar
> exploration.
> When we have an interplanetary economy, with the level of
> technology and access to resources that implies, answering the
> question "Why should we go to the stars?" with "because we can"
> will make a lot more sense.  If we have self-sustaining orbital
> colonies, then the expertise and infrastructure needed to build
> interstellar spacecraft is far more likely to be there, and the
> expense of obtaining the materials and construction labor will be
> far less.
> In other words, the culture that goes to the stars will be a far
> different culture than we have now, particularly in the economic
> sense.  This isn't the first time I've had to remind Kelly of
> that.

Thanks for the eloquent reply. The most believable scenario achieveable by 2050
that I've seen is the analysis by Dana Andrews on the economics of laser and
particle-beam propelled probe systems, but that's assuming a lot of Belt-based
infrastructure. If Inertial Confinement fusion can be properly developed then pulse
propulsion might become viable, but that still has major problems with neutron
damage since any forseeable system will involve deuterium, and so deuterium
reactions that produce neutrons. Which is why I prefer beamed power scenarios, but
they need lots and lots of power - kilo-terawatts [petawatts?] - and that's a bit
hard to provide. Huge focussing solettas, giant gas-core reactors and/or fusion
systems would be required. Is any of that achieveable by 2050?

I don't see star-flight by humans really happening until the Solar System is filled
with mobile cylinder cities and large scale mining of fusion fuels is underway.
That could happen by 2100, or 2150. By that stage more people will live off-Earth
than on and large-scale closed-cycle habitation in space will be common-place.
Alongside such developments I would also see longevity and cyber-augmentation, plus
various gene engineering techniques being well developed. We might not be able to
go the stars, but They might make themselves able to trek across the void.

I know we're discussing realiseable systems, but really how feasible are fusion
drives and multi-staging to get to 0.3 c by 2050? We haven't got fusion pulse, we
haven't got a closed space-going ecology, we haven't got high-strength, high-Tc
superconductors and God-knows what else we might need. So who's to say what is
possible? If go conservative we could build an Orion system that'd reach Alpha
Centauri in 400 - 120 years - that'd break the Global Economy to make. What would
it take to launch +300,000 tons of fusion bombs and equipment? A thousand HLLV
flights? At a billion a shot? Then there's actually making all those bombs, and the
risks of terrorism and so forth.

So what do we discuss? The physically possible, but what about the humanly
possible? What sort of people will cruise the stars? Not the middle-class liberals
that flash around at warp-speed on "Star Trek" and carrying on like it's some
god-damn soap-opera! It'll be people who want the stars for a whole variety of
reasons, but they'll be living and working together. Flying island states are more
likely than career-enhancing star-cruisers. Starflight won't be a part of a life,
it'll be a life.

So I assume fleets of colonisers because that's what it will take. Not small scale
Explorers. They're only feasible if a mission is just a couple of years, not
several decades. To do that you'll need ships doing +0.999995 c, and that's really