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Re: Engineering Newsletter

> Kevin wishes to interrupt:
> > Timothy replies to Kelly:
> ---  same with Kelly's 
> design, come up with a viable method of stopping and tell us how long it 
> would take to come up with the tech. (or lhow long it will take to 
> pre-load the decell track) Then when we have several methods, 
> we can rank them according to speed of travel, tech level, and other 
> factors, to come up with a viable method.  

Of the two ideas I came up with (launched fuel and stages fusion rocket) they
both are stuck with using stored on-board fuel for deceleration.  No solid
numbers yet but it looks like 20% to MAYBE 30% is doable.

In more detail:

For a fuel laucher based systems the ship takes off with a ful load of decel
fuel and accelerates up the accelleration track wich is pre loaded with fuel.
Its maximum speed is limited by how far they launcher can accuratly launch
the fuel.  I.E. how far from the launcher does the fuel become so dispersed
that the ship can't scoop up enough for its needs.

Anyway.  The ship leaves sol with its decel fuel.  Coasts to a star thats
close enough (T.C. would not be close enough, so I'm assuming Alpha C or
something else in the 4-6 ly range), then Decelerates with the onboard fuel.

For the return flight, it can eiather accelerate with stored fuel and decel
into sol using a Sol fuel launcher provided decel track.  Or they could,
maybe, biuld a fuel launcher atthe target system. This would allow that ship,
and subsequent ships, to make the flight at speeds not limited by on-board
fuel limitations.  Possibly at much higher speeds.

A multi stage ship is theoretically limited by how many stages you can get.
 But I think the specific impulse of the system will give an upper practical
limit.  Returning could be harder since you won't have all the stages.

I think the central difference between us is your expectation of being able
to colonise a world and self sustain a colony or base with only a couple
hundred people.  

Currently a self sustained society needs millions of people to keep going and
cities full of hardware.  I might be willing to accept that we might be able
to do it with tens or hundreds of thousands of people in 50 years; but not
hundreds, and certainly not with what a ship could carry.

So given my expectation that planets with a bio-sphere would be unsurvivable
for any period of time, and the crews will be strongly limited by the spare
parts the ship can carry.  The mision couldn't sustain the open ended
operations you seem to be assuming.  So going there doesn't give the crew the
option of living on their own, or starting a sustainable society.  This
probably accounts for our different reaction toward one-way missions.