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Re: Re: starship-design: Interstellar mission within fifty years

In a message dated 10/9/98 9:01:44 AM, zkulpa@zmit1.ippt.gov.pl wrote:

>> 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
>I don't think so. Controlling sustained fusion reaction
>and directing the output to achieve efficient thrust
>still wait for breaktroughs.

We don't actually need sustained, and certainly thats not a major breakthrough
eiather way.  Now the fact no one is doing any real applied work in fusion is
a major problem for our timeline, but it seems fairly likly a fusino drive
would get funding in the next few decades.

>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.

Thus my assumption of the nessisity of automated productino of thousands of
SSPS platforms.  A ring of them around the sun at 1 AU should do it.

>Not speaking about the waste heat (again - question 
>of efficiency, but not only).

Irrelavent.  The waste heat would be dumped into a area of space after The
power was converted from sunlight.  Average heat load in the area wouldn't
change much.

>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.

Manufacturing breakthroughs yes, but not science and tech breakthroughs.

>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?

I doubt we will ever build one.  They cost far more then they are worth.

>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.

That seems unlikely.  Space solar has enough disadvatages that I don't think
it could compete in a economy with fusion systems.

>> >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
>> 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.

Agree that Apoll made a lot of sence as a cold war "battle", but a historian
from 1919 would have found it pretty implausible.

Tech development was no a goal for Apollo.  As a mater of fact it was avioded
as much as possible, hence the crude space capsule expendable booster concept.

>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