# Re: Orbit B

```Kevin:

> > > No, think of a cone twelve light-years tall, with a base circle the
size
> > > of merc's orbit.  the angular deviations would be nearly
> > > impossible to measure.  Let's just consider a
> > > two-dimensional analogy. an isoceles triangle twelve
> > > lightyears to a side, with a 72 million mile base:====
> >
> >
> > Lets consider that if the beam is 72 million miles across, and the sail
is 10
> > thousand miles across; and the ship needs e18 watts of beam to hit the
sail.
> >  The total power over the entire beam would need to be about e25 watts.
I
> > think we are starting to outpower the sun here Kevin.

> No, the beam is not 72 million miles wide, silly.  the
> entire cone is 72 million miles wide at the base.  go
> back to the two dimensional analogy, the beam starts
> on one leg of the triangle, stays there for 44 days
> (half of merc's orbital period) then switches to the
> other leg for 44 days.  in both positions, it's beam
> width is only slightly bigger than the sail.
> (to overcome jitter effects).

But given the targeting cone.  The bem would still be 36 million miles off
center at the mid point.  I.E. it would miss the sail by tens of millions of
miles.  Since you can't know where the ship is.  You couldn't accuratly aim
for it.

Also this discusion started when Brain was describing how he would mount his
beam reflectors on a comet or something in Tau Ceti.  Given it would take 22
years for the reflector to tell earth where it was assembled....

Kelly

```