Re: RE: starship-design: Tugs

[kuo@bit.csc.lsu.edu (Isaac Kuo)]

L. Parker wrote:
>Kelly,

>> That could be a very good idea!  But would that up the power or weight
>> requirements of the sail system to much? 

>Well, yes and no. The dielectrics had much lower reflectivity, on the 
>order of 87 percent which means they were much less efficient to start 
>with than what we had wanted.

What happens to the light which doesn't get reflected?  If it's
transmitted, then 87% reflectivity is just fine.  If it's absorbed,
then we've got a problem.  A limiting factor to laser sails is
how much power per square meter they can handle without melting.

>But dielectrics only use milliwatts to 
>control the reflectivity, negligible amounts of power as far as we are 
>concerened.

A laser sail has plenty of power to spare.  Small pholtovoltaic cells
can generate a very useful amount of power just about anywhere you
want it.
-- 
    _____     Isaac Kuo kuo@bit.csc.lsu.edu http://www.csc.lsu.edu/~kuo
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