# Re: Orbit B

To Tim

> To Kelly,

> >> But this means that any beam, from Earth or from some kind of
retro-mirror
> >> would be impossible! (In fact this is one of the reasons I never really
> >> liked using a beam and always tried to think of taking all fuel along)
> >
> >You'ld have to have a fixed aim beam of huge proportions.  Say 10-100
times
> >the diameter of the sail (maybe it would need to be more?).  No I don't
think
> >the reflectors would work.

> But I planned the retro-mirror would be at about the same size as the
> earth-array. (Sounds awful doesn't it?)

Doesn't sound possible.  You'ld have to get some divergence.  You'ld need to
send a beam much larger than the sail/reflector in order to make sure their
was an acceptable sized hot zone for the ship to manuver slightly in.

> >> Anyway since the retro-mirror flies in front, it would know what the
path
> >> would be like for the Asimov, so it could calculate where
> >>  to direct using that data.
> >
> >But the ship would be reacting to the stern thrust of the earth beam
months
> >before it would get to the mirror, and the mirror could respond.

> No, the back- and forward beam aren't at the same place,
> they are at besides each other.

Then the relfector (and ship) would be under lateral thrust that would shove
it out of the beam, and the reflector work have to aim to hit the ship.
Since it couldn't know or see the ship to aim, it would presumably miss.

> >Besides how
> >could you keep the mirror perfectly focused with all the random
fluxuations
> >in the beam?

> With the capture and retransmit array (that has to be just
> about as large as the beam)

How would that help?  The beam from earth would be fluttery by the time it
got to the reflector or retransmitter array.  So that would chew up the
microwave converters of catcher mesh (depending).

> >How the hell do you focus a lose flapping mesh sheet, the size of jupiter,
> >while its taking 100s-1000's-? of G in acceleration?

> I still don't agree with the size of the sail and the beam. The sail should
> at maximum be 1 kilometre radius and the beam max 100 km radius.
> And if we can make this thing work, I assume the accuracy could be made
better too.

e18 in a 1Km beam?  Kept that tight over interstellar distences?  Neat trick.

> The mirror would not accelerate any faster than the Asimov, since we are
> smart enough to add some extra weight (if it isn't heavy from itself).

Thats a lot of waste mass, and it wouldn't effect it flaping.

Kelly