12 ms·

But the grinding machine costs (which is significant if you have 10 of them) and the grinding process takes a lot of time and cost (if you have 1 machine x 10 m

But the grinding machine costs (which is significant if you have 10 of them) and the grinding process takes a lot of time and cost (if you have 1 machine x 10 mirrors). I don't think these NASA/JPL guys are quite as dim as you seem to suggest (but you have more info) and they may have done a little cost/benefit analysis before embarking on the project.

WalterBright 4y ago
From their statements, no, I don't think any cost/benefits of making a twin were done. In particular, none of the respondents wrote anything about what the cost of R+D was relative to the manufacturing cost. BTW, I am not suggesting they are dim. But one can be the finest physicist in the world and not be familiar with cost accounting and manufacturing.