# Re: starship-design: Massively Distributed Computing for SETI

```> From owner-starship-design@lists.uoregon.edu Wed Mar 21 02:01:19 2001
> From: KellySt@aol.com
>
> [...]
> >> I can't see how this wouldn't be a trivial problem? Your not talking
> >> a high lateral movement, or any delta-V of the two stars.
> >> On the scale of the galaxy the two stars are right on top
> >> of one another.  (A couple light years
> >> out of a 30-40 THOUSAND light year orbital radius.)
> >>
> >For a starship what is important is not the _relative_ change
> >of the star position with respect to its distance from the center
> >of the Galaxy, but _absolute_ change of its position
> >(in light years, say). If the star moves a light year with respect
> >to the aim of the starship, the starship must simply travel
> >this additional light year (laterally, say) in order to catch it,
> >no matter how far (or near) the center of the Galaxy is.
>
> Relative movement is related to the degree of difference of the orbit. In
> this case the fractinal difference would be trivial.  As long as the two
> stars don't move relative to one another - effectivly they can be treated
> as unmoving for nav purposes.
>
Fractional - yes. But absolute - not necessarily.
If the Sun and the star are at different orbit, they do move
relative to each other - withe speeds often in tens of km per sec.
That may build to notrivial distances during years of travel -
not to mention inaccuracies in our measurements of relative speed,
distance, etc.

> >[...]
> >> Tacking, or otherwise manuvering into the  path of the beam
> >> is nessisary.  If you fly out of the beam you'll need
> >> secoundary motors to manuver back into the beam.
> >> You'll need manuvering  engines anyway for in systems work.
> >>
> >Notice however, that the lateral movement of the beam due to
> >any jitter od the beaming antenna will be rather rapid - in fact,
> >it may easily exceed the speed of light!
>
> So don't jitter.
>
Easier said than done.

-- Zenon
```