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>>>> I have an idea  <<<<
I mensioned to Tim that you couldn't build a ship that could carry a thousand
times its own weight in fuel.  True, but I forgot about staging!  You start
with a 1 billion ton fueled ship cluster driven by a 10 million ton engine
and support structure (yeah right.).  That engine is powerfull enough to push
the whole mess at speed.  

When you burn off 95% of your weight in fuel.  The ship cluster weighs 50
million tons, 20% of which is a first stage engine/structure thats WAY too
powerful.  You throw the first stage away and start a smaller secound stage.
 It weighs about 400,000 tons (about as much as 4 aircraft carriers) and can
push the 40,000,000 ton ship cluster. When you burn that down to 2,000,000
tons of cluster you throw that away that stage for a 70,000 ton ship with
5-10,000 tons of drive systems.  Which can use the remaining 390,000 tons of
fuel to get itself into the system.

stage  total weight (tons)     thruster pack and stage structure
1      1,000,000,000           10,000,000 
2         40,000,000              400,000  
3          2,000,000               70,000 ton ship 
                                 with 5-10,000 tons of 
                                  drive systems. 

This assumes a 100 to 1 thrust to weight ration for a fussion drive systems
(which is questionable), and once you get where your going, coming back is
out.  But it would give us huge fuel ratios for relativistic flight.
 Possibly a multi stage fusion craft to get to the star and build a fuel
launcher systems for two way flight?  I'll have to think on this.

> From T.L.G.vanderLinden@student.utwente.nl Fri Jan  5 11:40:02 1996
> > 
> > Available power sources:
> > 
> > Fission
> > Solar power
> > Fusion
> > Chemical
> > Other?
> > 
> > Available techniques:
> > 
> > Beaming
> > Energy storage in anti-matter
> > Other?
> > 
> > Places to go to:
> > 
> > Tau Ceti (TC)
> > Alpha Centaury (AC)
> > Pluto
> > 
> > Objectives:
> > 
> > One way trip
> > Two way trip
> > 
> > Let's assume that all the above are possibilities. What we should do is
> > calculate the size and feasability and discuss the (dis)advantages for
> > cases. We should NOT try to discard a method, but only give its
> > and disadvantages.
> > Of course we have done a lot already, only we haven't ordered it very
> > Maybe it is time to recapitulate our discussions. I think that we need a
> > complete survey, of course every one knows a lot of it, but I think that
> > don't agree about everything yet, but we also don't know exactly what
> > differences are.
> > So we should try to come up with a kind of report. (Of course easier said
> > than done)

Good idea, we have pretty well argued threw everything, and a summary would
be a good idea.  Assuming we'ld dfo it.  Several of us have suggested it.  A
fw said they were starting.  Oh well.  Using Zenons framework

> Here I would like to remind about my attempt (a year ago)
> to start recapitulation effort of all discussed options.
> Below follows the sketch of the beginning ;-))
> of the DESIGN SPACE summary I have started then.
> There should be, of course, many more aspects
> listed, like target(s), life supply 
> (e.g., stored food/hydroponics/farming;
> all crew awake/all crew hibernates(or something)/mixed, etc.),
> command structure, project financing.... &c &c.

>                      *       LIT "ASIMOV"      *
>                      *     Starship Design     *

You might have noticed I hate the name Asimov for the ship.  It gives the
whole project a grade school feel.  I mean lets be real.  This is a name that
would never be acceptable to a real starship project.

> The DESIGN SPACE discussed:
> 1. Type of Mission:
>    * Robotic
>      * Fly-by (no braking nor stop at target)
>      * Exploratory (stop at target & explore)
>      * Pathfinder (ahead of manned one: scouting/early warning)
>      * Supply (after the manned: catching on the way or at target)

Fly by doesn't make much sence.  If you just want to observe, you could do
that just as well from here with big telescopes.  Exploratory and Pathfinder
have the same drive problems as the main ship, but greater funding problms
and less capabilities.  Pathfinder would be good as a warning scout ahead of
the main ship though.

>    * Manned:
>      * Without crew procreation
>        * Suicide (explore and die before your time when supplies end)
>        * One-way (outpost construction and stay till natural death)

Suicide and one way are the same.  We couldn't biuld a self sustaining
outpost, and wouldn't fund resupply flights forever unless there was
something in it for us (or a fantastic improvement in star drives back home).
 NO ONE would fund a one-way flight.

>        * Round-trip (return to Earth, 
>          possibly with some crew left at the outpost) 

About the only practical option.  If we can't get them back, we woun't be
allowed to send them.

>        * Multi-step (start to new target from the previous one)

We are having a big problem even thinking how to get to one star and back.

>      * Multigenerational
>        * Short-range, but long (slowship)
>        * Long-range, thus long even though fast (fastship)
>        * Colonization

We beat this one to death. 
   - If its going to take you that long to get somewhere, wait for faster
ships to be built.  Since those ships will get there before you do anyway.
   - People who might want to go explore a star, certainly wouldn't settle
for spending the rest of their days stuck in a ship with nothing to do.
   - The people who get there will have no allegence to the origional
mission.  In the United States about a century or two back, a lot of
religious or other groups decided to go off into the wilderness and found a
utopia.  They eiather didn't plan and died out quick.  Or they lasted about 2
generations.  The grand children, didn't have their zeal, so they left, or
rebuilt the city/culture along more conventional lines.  Why would the grand
kids bother to do our exploration for us.  They never asked for this, and
were never asked.  I'ld bet they'ld eiather sit in the ship and wait for a
followup mission to rescue them, or turn around and go home.
   - The people who get to the star wont be the ones you sent.  They wont
have the same skill mix as the first generation.  They wont have any
familiarity with planets, exploration, the shutles and rovers they'll need to
use, etc..
   - The ship would need to be much larger and better equiped to handel
multiple generations (only one of which is working).  Better medical, people
will take more risks with their own lives then with their kids, and old
people need MAJOR medical.  Assuming we don't do the Canadian health care
trick and just tell them their lives are no longer cost effective?
   - Equipment has a life expectency too folks!  Usually less than 40 years.
 We wont be able rebuild everything in flight. So the ship will grow old and
die around the crew.  Even if it makes it, by the time it gets their its
exploration gear will be in prety tired shape in the bay, and noone will
remember how to fix it.  (Sorry you can't just look it up in a VR sim.)

Multi-gen is interesting in that its both technically more risky, expensive,
etc.. and because of its long time lines, its certain to be a waste of time.
 Again, it will be certian to not get there first.  Also there is a moral
issue about throwing generations down a dangerous mission for no good reason.

> 2. Type of Propulsion
>    * Main source
>      * All fuel on-board
Not possible unless you have a very slow ship, or anti matter.  Niether is
very practical. Of course that assumes conventional physics.

>      * Use the interstellar medium

We have no real idea how to, or for that matter know whats out there to use.

>      * Power from installations at Solar system

Beamed power or fuel launchers have the advantage of offloading the need to
carry the heavy fuel (and power systems) with the ship.  That improves the
ships power to weight ration significantly.  But the systems are difficult to
do, limit range, and don't seem to help us to slow down.

>    * Main type
>      * Fission
>      * Fusion
>      * Antimatter
>      * Sails
>      * Other?

Fusion and anti-matter could power a ship.  Microwave or laser sails could
drive it.

> 3. Gravity on board
>    * Zero or small gravity
>    * Near-g gravity
>      * Centrifugal (rotational)
>        * Whole ship
>        * Habitat ring only
>        * Tethered sections
>      * Acceleration
>      * Mixed

I think the idea I came up with for a multi segmeny hab ring is the best.  We
need gravity for the crew, and the rotating hab segments will allow it to
adapt to changing thrust directions.  Unless the ship can operate under
continuous thrust for the full flight.  This seem best.

> 4. Mission composition
>    * Single ship
>    * Multiple ships
>    * Manned plus robotic:
>      * Pathfinder probes
>      * Supply ships

Given the size the main ship must be, I don't think we could afford 2.  Which
is a pity from a safty standpoint.  A robotic pathfinder would be a good idea
if it would work, but I'm dubious.  

A suply ship sounds a little risky.  How would you like to be waiting in the
target system for the next 5 years groceries.


Zenon, did you CC yourself at an AmericaOnline account?