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

In a message dated 10/5/98 10:20:23 AM, ajcrowlx2@ozemail.com.au wrote:

>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
>>  > 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
>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-
>infrastructure. If Inertial Confinement fusion can be properly developed then
>propulsion might become viable, but that still has major problems with
>damage since any forseeable system will involve deuterium, and so deuterium
>reactions that produce neutrons. Which is why I prefer beamed power

Ah you don't have to use fusion fuels that produce neutrons in a pulse fusino

>they need lots and lots of power - kilo-terawatts [petawatts?] - and that's a
>hard to provide. Huge focussing solettas, giant gas-core reactors and/or
>systems would be required. Is any of that achieveable by 2050?

You could build fleets of space solar power platforms, but unless you have
masive space based automated mining and manufacturing systems, you couldn't
afford them.  But then perhaps perfcting such systems could drive a government
to fund such a program as a show peice.

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

These are a lot od assumption.  The one thing we did all agree was that we
couldn'r seriously predict what the science or economics past 2050 would
credably be.

>I know we're discussing realiseable systems, but really how feasible are
>drives and multi-staging to get to 0.3 c by 2050? We haven't got fusion
>haven't got a closed space-going ecology, we haven't got high-strength, high-
>superconductors and God-knows what else we might need. So who's to say what

We do have pulse fusion systems that could reasonably be developed in the next
50 years into functioning drives.  Life support and food storage that would
last a 30-40 years for a round trip is fairly doable.  And thats about all we
need to build a 40ish% od c system.  Given a BIG checkbook a combined beamed
power and fusino system COULD be built in mid 21st century.  However unless
some manufacturing advace brings that cost WAY down, no one WOULD pay for it.

>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
>it take to launch +300,000 tons of fusion bombs and equipment? A thousand
>flights? At a billion a shot? Then there's actually making all those bombs,
>risks of terrorism and so forth.

Actually it would be harder to do multri century flight, and really stupid to
do it.  Obviously in a century or two science and technology will make
increadable strides, so unless you can get there in a couple decades, you
should just wait for a faster ship.

>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
>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
>reasons, but they'll be living and working together. Flying island states are
>likely than career-enhancing star-cruisers. Starflight won't be a part of a
>it'll be a life.

Unlikely, even more unlikely then Star Trek types.  Flying cities need to pay
their way.  You can't just take off with them.  Thats like buying and removing

Since the resources of this star system could support any conceavable
planetary civilization for  tens of thopusands of years.  There'ld be no need
to pull up stakes and move on for greener fields.  So why build and launch a
interstellar colony?

>So I assume fleets of colonisers because that's what it will take. Not small
>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

Can'y say a ship that fast (or faster) would be silly.  We can't build it, but
someday we'll be able too.