Coaster 18, Don't reflect concentrated sunlight

I've come to the conclusion that reflected the concentrated light may not work, especially if the light is rather intense.  It may burn or melt the mirrors.  Instead of doing that, the next idea is to reflect the sunlight to the concentration dish.  This may require one or more mirrors to be placed at some point in space ahead of the dish.

These mirrors will pivot as needed to keep the sunlight focused upon the dish.

The rest of the setup will be like a concentrated sunlight dish as they are now made, except that electricity will not be made, but heating a reaction mass instead.

It is now a matter of optimizing the size of the mirrors so as to make the amount of energy needed to achieve the goal of an ISP comparable to a nuclear thermal rocket.

Update:

Rather than doing a completely new post, I'll add another quick thought here.  If an aluminum source can be found on the moon close to a perpetual light location at the poles, it may be feasible to make these things and get the fuel from them at close proximity.  In other words, most of what you need to launch these things could be on the moon at these polar locations.  Hydrogen from water and aluminum from the regolith.  You can make mirrors out of the aluminum.

As mentioned in an earlier post, the main mission would be to mine asteroids.