The figure of the mirror is held in place by the stiffness of the glass. With multiple mirrors you need a massive mirror cell or dynamic motors to constantly fight against the sag from gravity. In space it is easier because gravity is taken out of the equation. There was a professional telescope called the MMT which was arranged in a six gun fashion. But that was just to have something to do until the big onepiece of glass was ground, figured, and polished. So there is no real advantage in the long run. DT From: Jay inUT <jayleads@gmail.com> To: Utah Astronomy <utah-astronomy@mailman.xmission.com> Sent: Wednesday, August 26, 2015 6:58 PM Subject: [Utah-astronomy] Making a 36" from many smaller mirrors Ok, I got approached by my boss at work about the possibility of making a 36" mirror for observing from say several 8 inch mirrors (think an arrangement like James Webb). In thinking about this to me it seems that there are issues here about positioning the mirrors and ensuring that once ground, they form a parabola etc. So what are the thoughts on this? Can an amateur make a large mirror from smaller mirrors and what would it take? Just curious and I know what my reply was but I said I would inquire. -- Thanks! Jay _______________________________________________ Utah-Astronomy mailing list http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Send messages to the list to Utah-Astronomy@mailman.xmission.com The Utah-Astronomy mailing list is not affiliated with any astronomy club. To unsubscribe go to: http://mailman.xmission.com/cgi-bin/mailman/listinfo/utah-astronomy Then enter your email address in the space provided and click on "Unsubscribe or edit options".