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Re: starship-design: Beamed power

> From: "Kevin 'Tex' Houston" <hous0042@tc.umn.edu>
> > 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.
> 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.
Not all jitter must necessarily be fast - 
what about gravitational influences from a stray comet or asteroid
sweeping through a few millions of kilometers from the transmitter?
Also, we considered some time ago the design with
the beam spiraling due to orbital motion (around the Sun) 
of the transmitter(s). Otherwise, the orbiting transmitter(s)
must constantly change its (theirs) aim along the orbit,
which may cause additional jitter, too fast to compensate
adequately at the starship distance.

> 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.
No way. Any message to Earth signaling the trouble
will take years to go here, and the same time for
the correction to appear at the starship place
(not speaking about that the starship will be in quite 
a different place at the time...).
If there CAN happen such thing as the beam veering to the side,
I can see only two solutions:
- a possibility of the ship to chase the beam
  (which means sideways motion);
- send back the farewell messages and declare
  the mission to be "The First Valiant Suicide Interstellar Flight"...

> > Concerning the shielding/drag problem:
> [...]
> Perhaps a lower powered beam could be sent ahead by several months/years
It will probably not work -  
wwhen the ship moves forward, the beam-swept empty
tunnell will be filled again with the matter moving from the sides.
The "sweeping front" must be at all times not too far before the ship
to prevent the filling.

Remember - nothing is stationary in space...

-- Zenon