Re: RE: starship-design: Interstellar Probes

[KellySt@aol.com]

In a message dated 8/14/98 4:07:10 PM, lparker@cacaphony.net wrote:

>In our discussions, we have been able to pretty much agree that there are
>
>several viable methods of accelerating a ship up about .3 or maybe even .4
>
>c. Unfortunately, these methods almost always rely on some trick which
>
>cannot be provided at the other end to slow the vehicle down. Simply
>
>doubling onboard reaction mass or fuel is not the answer. If you do the math
>
>you will discover that doubling the mass of the vehicle will decrease the
>
>cruise velocity significantly and drastically increase mission length.
>
>
>
>Propulsion wise, what we need as a BARE MINIMUM is a self contained
>
>accelerate/decelerate capability in the 100,000 m/sec range, or put another
>
>way, a 200,000 m/sec total change in delta v. This would enable us to reach
>
>the nearer stars within the lifespan of a single person (but not necessarily
>
>to return within one person's lifetime.)
>
>
>
>I am working from memory here, but I think the best we can currently manage
>
>is only 200 m/sec, which is quite a bit shy of the minimum. We may be able
>
>to reach 100,000 m/sec buy combining several different systems i.e. a
>
>powered perihelion maneuver with a maser sail last stage, but this is again,
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>only one way.
>
>
>
>Lee
>


Ah My two concepts used a fuel launcher to boost the ship to speed without
internal fuel. or a maaser sail here to accelerate it to speed.  Both used
onboard fuel to decel it into the target starsystem, and used mined fuel to
accelerate it back toward Sol.  

Round trip time was about 25-30 years.

Kelly