Mirror casting for the Giant Magellan Telescope (GMT)

[gary]

In a 6 Jan 2018 article at ieee.org (https://spectrum.ieee.org/video/aerospace/astrophysics/casting-a-20-million-mirror-for-the-worlds-largest-telescope), Celia Gorman reports on the casting
of the seven mirrors for the Giant Magellan Telescope (GMT) at the
University of Arizona.

The work takes decades and the first mirror was cast back in 2005.

Each mirror cost US$20 million and takes more than two years to make.

Story and video here :-
https://spectrum.ieee.org/video/aerospace/astrophysics/casting-a-20-million-mirror-for-the-worlds-largest-telescope

[multiweb]

Very cool. I wonder if the ESO one will be partly operational by then as it is more modular.

[xelasnave]

Wow the price.
Thanks Gary.
So I thought how to build a big scope cheap.
A saterlite made from a shaped ballon a coating if reflective mirror stuff cover with fibre glass ...remove the ballon and there is you primary mirror.
A wonky surface but you make it a diameter of 500 feet an a long focal length by a sat following with the camera ...gear to keep them lined up.
Then softeware to correct anomolies by averaging the image from the little less than perfect mirror surface.
All you have get up there is a ballon something to fill it mirroring and fibre glass..well carbon fibre.
ALEX

[skysurfer]

Well, seven single 8m mirrors making a 24m composite mirror are much more difficult than 984 1.4m hexagonal segments making a 39m composite main mirror which makes the E-ELT on Cerro Armazones, Chile.

[multiweb]

Right on time (https://www.eso.org/public/news/eso1801/?lang). :lol:

https://youtu.be/85Qcbn8nlaM

https://youtu.be/B2wK3ybhw18

That little video with the forklift carrying one element of a 39m diameter total array just shows how clever the concept of a modular system is. Transport logistics won't be as daunting as the Arizona project. Hopefully it performs as well optically.