Re: starship-design: FTL travel

[KellySt@aol.com]

In a message dated 4/21/00 9:58:43 PM, lparker@cacaphony.net writes:

>> Or biulding a titanic in segments to be assembled in the
>> feild.  Prefabing
>> little segments of a statin to be assembled in orbit means
>> lots more seams to
>> leak.  Besides its not like your likely to have a lot of
>> things in the
>> station that you'l have lots of copies of.  So mass productin
>> is a bit
>> dificult.
>
>You still missed the point, if you are only building one of the end product,
>it doesn't matter if you prefab it in sections and boost it or boost it
>all
>at once. 

Well actually if you launch it in peaces its much more likely to work right, 
and not leak!

>Cost savings arise when you build the SAME piece over and over
>again. (I will grant that you can't build an interstellar ship and boost
>it
>all in one piece, at least, not yet.)
>
>However, if you have an industry that is mass producing engines for
>instance, it will be cheaper to use several of those engines if necessary
>rather than building one special purpose engine to do the same job. 

Probably true, course that assumes your starship can use off the shelf 
engines.  

>It
>will
>be cheaper still if those engines are all being mass produced in orbit
>from
>materials which are already in orbit rather than boosting ANY of the
>components from Earth.

Thats a big asumption.  No reason to think a space built peace of equipment 
would be cheaper, likely to be more expensive.  Smaller market and far 
greater expenses for the space based manufacturing equipment and personel.


>>
>>
>> No because the infastructure to build the probes and early
>> stations is much
>> larger and heavier then years worth of probes and statins would be.
>
>Yes, the infrastructure IS expensive. I stated that right up front. But
>it
>is also paying it's own way. So the cost is amortized across other projects
>besides just one interstellar craft.

Are you sure its paying its way?  Unless there are a lot of projects, you 
could be costing more.


>> Expensive launch is much less of a problem since the bulk of
>> the cost of a
>> good reusable is building the craft and keeping up its
>> facilities and such.
>> So if you quadruple the launch rate the total cost goes up
>> far far less.  In
>> some cases hardly at all.  Just fuel and wear.
>
>Not true. See below for more.
>
>> With DC-x they found if you
>> launched 3 times a week or three times a year you had to keep
>> most of the
>> same people on in similar pay rates.  Spare parts and such ae
>> a pretty low in
>> comparison, and ofcourse the cost to develop and build the
>> craft are divided
>> over the total number of flights.
>
>That much is true but keep going....
>
>> If your lifting 10,000 tons you can cut lift costs
>> dramatically.  Cut costs
>> to 1/100th that of a titan or such and the total lift cost would be
>> $2,000,000,000  About the cost of 1 year of shuttle launches
>> (under 200 tons
>> possible lift).
>
>Ahh, but here is the mistake. You can't realize significant cost savings
>with EXPENDABLE boosters such as Titan or Ariane no matter how often you
>launch. Sure, you get to amortize the cost of the launch crew and facilities
>across more launches, ===

I was refuring to reusables, obviously there can't be any significant cost 
savings with expendables!



>BUT, that launch crew and those facilities cost
>thousands of times what a DC-X costs to launch in the first place. Now
>if
>you can launch a DC-X on such a schedule you are right, you will reap a
>one
>hundred fold decrease in launch cost because it IS NOT EXPENDABLE.
>Unfortunately we need a one thousand fold decrease even for the mundane
>orbital industry I am promoting. 

For those kinds of reductions, you need enough market to keep fleets of such 
vehicals very busy.  You are after all talking about reducing cost to orbit 
to costs simlar to trans ocean air frieght.  That takes similar sized 
markets, or radically improved tech.  Some ae on the books, but you need 
massive launch requirements to run them at efficent enough rates. 

>Nothing currently on the drawing board
>is
>capable of putting an interstellar craft into orbit even if we could build
>it. Not to be repetitious but, you cannot reduce cost by 100 times no matter
>how many times a year you launch an expendable booster.
>
>> Shows you how bad current launchers are.  In theory the lift
>> costs could be
>> cut even another factor of ten or 100.
>
>1000!

Thats wahat I said.

>> Now obviously your not going to want to lift millions to
>> hundreds of millions
>> of tons for a big starship if you could get it cheaper in
>> space.  But you
>> wouldn't want to life a thousand ton steel mill to make 40
>> tons of steel.
>
>Which is why I said LOTS of orbital industry paying it own way doing other
>things. The steel for the interstellar probe becomes just one more job,
>not
>THE job.

Ok, then you need a market large enough to keep those facilities that busy.



>> >Third, what do you want to see, a repeat of Apollo? Okay
>> lets spend ten
>> >trillion dollars to put a man on the third planet of Alpha
>> Centauri and
>> >then
>> >go home and quit? Not me.
>> >
>> >I want to see a thriving orbital industry sending hundreds
>> of ships out
>> >to
>> >mine asteroids, ferry goods to and from orbital
>> installations, the moon
>> >and
>> >the planets. Research stations all over the solar system,
>> inhabited stations
>> >all over the place. In short lots and LOTS of experienced
>> orbital know
>> >how.
>>
>> Then you don't want the interstellar or any exploration
>> missions, you want a
>> earth side market for your space based industry.  Without
>> that it will all
>> blow away to dust like NASA after Apollo.  Doesn't mater how
>> much stuff you
>> put up there.  If its up there for no real general pourpose, It'll be
>> abandoned.
>
>Similar arguments abounded when America was colonized. You should really
>read some of the history (and I don't mean the popular sort) of the early
>days of America. European investors tried all kinds of crazy schemes to
>make
>a profit in America. Glass blowing comes to mind. A man decided he would
>create a native glass blowing industry to export glass bottles and such
>to
>Europe. Wonderful idea, but it could never compete with the glass which
>was
>being made IN Europe, which was invariably cheaper because of transportation
>costs. Nevertheless, things did work out that there WERE things to trade
>for
>and here we are today.
>
>I believe that Earth will always be a market for goods which simply cannot
>be manufactured in a gravity well or in atmosphere, but that eventually
>(and
>rather sooner than later) space born consumers will predominate the demand.
>Just as in the early days of Colonial America, a mindset will develop that
>we (the space faring) will trade with ourselves first before we give
>anything to the Earth borne who put us here in the first place.

Nice list, but it doesn't alter the major problem.  What can you sell to 
earth in enough volumn to pay for the operation of the platforms.


>> >Anything can be manufactured in space. Many things can be
>> manufactured
>> >BETTER. I have a get out of jail card and I think space is
>> the equivalent
>> >of
>> >Boardwalk and Park Place with hotels...very profitable.
>>
>> Good idea, but a different conversation.  Space tourism could
>> easily dwarf
>> anything we're talking about.  It would nessisarily keep any
>> manufacturing
>> facilities going.  (How many factories moved to Cancun, or
>> Jamaca?)  But they
>> would feed a HUGE launch industry and provide launch
>> infastructure to drool
>> for, as well as residence facilities for research and
>> consructin platforms to
>> house their staffs on.
>
>Interesting point, but not quite the one I had in mind. Still you are
>correct, any industry in space that creates the demand for more industry
>starts a chain reaction that cannot help but to beneficial to us in the
>long
>run. I'm not too proud to accept tourism or even entertainment as the
>vehicle. Hmmm, we're back to my not so hidden agenda problem again!
>
>
>Lee

Kelly