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Re: starship-design: Interstellar mission within fifty years

> From: KellySt@aol.com
> In a message dated 10/7/98 12:43:35 PM, zkulpa@zmit1.ippt.gov.pl wrote:
> >Ad. 1: Propulsion
> >-----------------
> >I think it will not be possible, unless some real breaktrough
> >occurs in one or more propulsion system ideas that seem feasible
> >from our perspective, namely:
> >- fusion rocket;
> >- giant lasers (possibly solar-powered);
> >- antimatter rocket (including an efficient antimatter factory).
> >I mean, unless the real working design will be proposed, 
> >a prototype build and tested in space.
> >As for now, nothing of the sort seems to occur
> >in the foreseable future.
> breaktrough to me implies a fundamental jump in science or technology.  
> I would see where fusion or huge laser system would require eiather. 
> The fusion and microwave sail system I last sujested seems to require none.>
I don't think so. Controlling sustained fusion reaction
and directing the output to achieve efficient thrust
still wait for breaktroughs.
Concerning lasers/masers, we are speaking of GIANT lasers -
that is, teravats of power - with current solar cells it means
tens or hundreds of kilometer arrays, which makes it
highly impractical, if at all possible to build
and keep in operation for tens of years.
Not speaking about the waste heat (again - question 
of efficiency, but not only).
The question of scale is important - for interstellar
propulsion, scales of energy, size, mass, etc. are orders 
of magnitude larger than any tested by humanity till now,
which really calls for breaktroughs to make it work.
Like the space elevator - theoretically possible, and
we have even produced an appropriate material (buckytubes).
Do you think we will build such an elevator within 50 years?
And a viable starship is even harder, in my opinion...

> Thou given the extream lack of effort in fusion or space solar power sat , 
> now its obviously not progressing. But future demand is expected to boost 
> interest in the near future. A big problem is the two are competitors.  
> So if fusion is developed, space solar would likely be abandoned.
Not necessarily. They may find different application niches.

> >Ad. 2: Infrastructure
> >---------------------
> >Summing up, if something does not, rather dramatically,
> >change the attitudes and goals of humanity concerning space,
> >the probability of launching a starship within fifty years
> >is very, very low.
> We can evaluate could do's, easier then would do's. Like I've said, we never
> did figure out why anyone would do such a masive project in 2050, but then
> Apollo didn't make any sence eiather.
No, it had a pretty good sense - that is, political (mostly):
to show those Ruskies that we are better anyway (after the Sputnik).
And a technology advance sense too (though mostly subordinated to political).
Unfortunately, by lack of determination and, let us say, simply guts,
most of the technological & political thrust produced by Apollo
was promptly wasted.

As, fortunately, I do not think that we will have United States of Earth
within 50 years or so, the political sense for going interstellar
may surface again. Especially with space/Mars/asteroids/etc. human 
colonies in place - either one/some of them will want to show its
independence and advanced technological power to those dirty Earthmen, 
or Earth power(s) will want to be the first at this next technology 
power step.
Though I am afraid it will take more than fifty years.

-- Zenon Kulpa