Retro-mirror

[T.L.G.vanderLinden@student.utwente.nl (Timothy van der Linden)]

>>Tims Says
>>That means a longer trip and if we want the same end-velocity, the energy
>>has to be beamed over a longer path.
>>And we are not talking about a little bit more weight, assuming fusion fuel
>>we should at least count with a ship that is 5 times heavier (assuming
>>end-velocity of less than 0.3c).
>
>See Phase 3 of my paper on the second Mars Hybrid (I still have things to 
>transmit about it but that will have to wait till after I've done some 
>homework these next few days).  Basically it says that you launch a maser 
>reflector ahead of the Asimov to redirect the maser beam for deceleration. 
> I seem to recall you making a mension of this idea sometime before I joined 
>the discussion group.  How did that go?

I proposed a flat mirror (since a concave one would need to refocus, which
is too difficult) the main reason why no one (?) liked it was because the
technical ability to make a perfect flat mirror would not be present. So
having a not perfectly flat mirror most of the reflected beam is difussed in
all directions except that of the Asimov. (This assumes the mirror has to
reflect over a rather large distance, somewhere around 1 ly)
Oh yes, then there was another problem: ideally the reflecting beam an
reflected beam would be in exact the same direction, so that means the
Asimov could not make use of the one without using the other (that went in
the wrong direction).
My design was made in such a way that at least the latter problem was solved.

Timothy

P.S. Some of the latter problem is also discussed in some other letters from
yesterday, but I added it for a complete oversight.