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

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In a message dated 3/21/01 7:24:49 AM, zkulpa@ippt.gov.pl writes:

>> >> 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.

10 km/s is about 310,000,000 km per year.  About 16 light minuttes, or 2 au,
or Earth to Mars on a good day.  That is completly trivial to a starship!  A
hundred times that is still completly trivial.

>> >[...]
>> >> 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.

We do that on big scopes, and besides with phased arrays over thousands to
tens of millions of miles, its handelable.
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