starship-design: Kevin's reply about Tim's summary

[TLG.van.der.Linden@tip.nl (Timothy van der Linden)]

>Nice job Tim.  here are some solution ideas for your problems list.

Thanks, it should appeal to you most, since you've a beamed ship design.

>#9  redshift causes the momentum to decrease:
>#15 doppler shift changes reflectivity:
>
>Sweeping the beam into higher frequencies, and then back down, as the
>mission prgresses; would allow the ship to receive it energy at a near
>constant frequency.  Any slight deviations should be within tolerance.

True, I guess we figured that out before, but I will add it to the summary.
The only trouble I see with this is that the beaming station needs tunable
masers/lasers. I know this is possible, but doesn't make the design easier.

Of course, increasing the frequency will still result in decrease of
momentum, only the people on the starship won't notice. 

>#14. communication:
>
>Using different wavelengths of EM for engine, comm.
>
>for example, if you are using Maser for power, then you should use a
>laser to communicate.  The laser guide beaming messages back to earth
>could be made of plastic or glass which would be totally immune to
>microwaves

Yes, that's true, I wonder why I didn't think of that a long time ago.

>#16 acceleration means limited beaming time.
>
>As we say in the Computer Biz, "That's not a bug, that's a feature."

That indeed is a way of looking at it.

>18 could be solved by moving several large asteroids (or lots of smaller
>ones) into a proper orbit around the sun.  (one that is normal to the
>line connecting the two suns.)
>since we'll have to build this thing out in space, I'll bet we have a
>lot of slag/waste that could be used to 'anchor' the transmitter in
>place.  a conventional rocket or ion engine would be much better for
>conteracting the beams thrust.

Yes, I'll add using a mass momentum engine.

>---------start new idea -------------------
>
>Each transmitter could be a stationary fusion rocket with the beam
>pointed in one direction, and the fusion exhaust (at very low speed)
>pointed in the other.  Since the whole thing is stationary, it could be
>refueled periodicly by robot tenders.  The fusion motor could tap most
>of the kinetic/thermal energy of the fusion products to provide
>electricity to power the transmitter, with a little left over kinetic
>energy and a fair amount of mass to provide a counter balancing force.
>
>---------end new idea -------comments?-----

The idea is nice, although supplying millions of fusion reactors may not be
something you'd like to do. We'll use a total of say 1E18 Watt, that's
roughly 5000 kg of fusion fuel per second. Or about 4 times the weight of
the ship per day.
(Eh, I'm assuming that we use the beam for a 1E8 kg ship, not for a probe)

I'd like the simplicity of solarcells better, even though they will be much
more plenty. In general they will be easier to build and need less care.

Timothy