Re: Re: RE: RE: starship-design: Re: Perihelion Maneuver

[KellySt@aol.com]

In a message dated 12/1/97 7:50:01 AM, kuo@bit.csc.lsu.edu wrote:

>>>what I am not comfortable with is station keeping, ALL of 
>>>the components of the system will experience thrust as a direct result of 
>>>the power being transmitted. The laws of physics can't be thwarted, it
will 
>>>still require as much or more reaction mass as any other concept (probably

>>>more) the only difference is that it isn't necessary for the fuel to be 
>>>aboard the vehicle.
>
>This actually isn't a concern.  The effect of thrust is inversely
>proportional to mass, and the emitters are VERY HEAVY compared to
>the thrust they emit in beams.
>
>This should be intuitively obvious.  If you had a laser emitter which
>could impart decent thrust on itself, you could use _that_ as a photon
>rocket.  (Then you wouldn't even have to worry about focussing the
>beams and you could use it for deceleration also.)
>
>The real concern is whether you can build that the huge honking
>emitter (or emitter array) in the first place.  It's dizzyingly
>massive and big.  If you can build it, then it's not going to go
>anywhere just because of the (relatively) puny beam it emits.

Agreed, thou after a year or so it could throw them around in their orbits.


>>At least the fuel/sail system itself seems prety solid and relyable.  No
cryo
>>tanks or unstable fuels.  Pretty simple brute force tech.
>
>You can say Forwards pure sail system is also "simple brute force tech".
>Actually, it requires much less technology than this "fuel/sail" idea.
>It doesn't require exotic fusion technology.

However the drop sial/reflector had serious problems and would probably not
be able to function, much less acuratly target and decelerate the ship.
 Which is why we droped it from consideration a couple years ago.


>However, the sheer size of that "brute force" is inconceivably massive.

So was the Sat-V concept at the time.  But I agree the scale and its implied
cost are critical problems.


>Especially when you consider that a modified design would only require
>a fraction of a percent of the effort.

But as I listed before, and went over with numbers, your modified design
wouldn't save a dramatic amount of power (possibly none), but would add a
serious intercept problem (scatering your hundreds of fuel packages over
about a light year and a half).

Kelly