RE: starship-design: Beamed power

["L. Parker" <lparker@cacaphony.net>]

Kevin,

>> The tugs shepherding the sail will be needed in any case,
> especially if the whole construction should be able to make
> sideways manoeuvres to follow the jiggling (or spiraling) beam.

[L. Parker]  Something I have been wondering about for awhile, why 
bother trying to follow the jitter of the beam? Wouldn't it be better 
to accept some degradation in over all acceleration by ensuring that 
the beam is wider than the margin of error (jitter) even at the expense 
of acceleration? The advantage is obvious, no steering, just stay on 
course. The worst that can happen is that it takes slightly longer to 
get there.

I don't think sideways manuevers will be possible (or desirable) the
beam should  be a straight line connecting the two suns.  If any
sideways motion of the beam occurs, it will be either too fast (jitter)
or will take us away from the system.

The number one problem with a beamed system is what to do if the power
cuts out.  All I can think is that the crew will have to stay the course
and hope that earth gets things straightened out before the ship impacts
the target system's sun.

[L. Parker]  If the beams cuts out, they have worse problems than steering.

> Concerning the shielding/drag problem:
> Or make the sail partially transparent.
> 

[L. Parker]  Or perhaps periodically replace the old sail with a new 
one and time the changeover so that a new high power pulse is allowed 
to "pass by" the ship to keep the path ahead clear.

> (*) Hope it will dissipate before reaching the target system
>     and wiping out the life or whatever from some planet(s) there...
> 
[L. Parker]  !!!What are you going to do? Focus the entire output of 
the sun for several minutes at Tau Ceti? At closer ranges, I might be 
worried, for instance, Mars might experience some severe polar cap 
melting if it was caught in the beam, but I really don't see us generating 
enough power to do any damage at that range. There is a big difference 
between cosmic dust and a planet.
 
L. Parker
                                                           (o o)
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A sufficiently incompetent ScF author is indistinguishable from magic.