Free Astronomy Magazine September-October 2023

SEPTEMBER-OCTOBER 2023 manufactured, while M2 and M3 are cast and in the process of being polished. Progress on M4, an adap- tive, flexible mirror that will adjust its shape a thousand times a second to correct for distortions caused by air turbulence, is particularly im- pressive: all six of its thin petals are fully finalised and being integrated into their structural unit. Further, all six laser sources, another key com- ponent of the ELT’s adaptive optics system, have been produced and delivered to ESO for testing. All other systems needed to com- plete the ELT, including the control system and the equipment needed to assemble and commission the tel- escope, are also progressing well in their development or production. Moreover, all four of the first scien- tific instruments the ELT will be equipped with are in their final de- sign phase with some about to start manufacturing. In addition, most of the support infrastructure for the ELT is now in place at or near Cerro Armazones. For example, the tech- nical building that, among other things, will be used for storage and T hese hese two images also show the progress of the work on the ELT site. Like the previous one, they were taken on June 23 but, as can be easily understood, using a drone. The people visible around the gi- gantic structure give a sense of scale and highlight how big the ELT dome will be. Beyond the construc- tion site, the shadow of Cerro Ar- mazones can be seen, projected onto the desert landscape. [ESO] coating of different ELT mirrors is fully erected and fitted out, while a photovoltaic plant that supplies renewable energy to the ELT site started operating last year. Construction of ESO’s ELT was kick- started nine years ago with a groundbreaking ceremony. The top of Cerro Armazones was flattened in 2014 to allow for space for the giant telescope. Completing the remaining 50% of the project, however, is anticipated to be significantly quicker than building the first half of the ELT. The first half of the project included the lengthy and meticulous process of finalising the design of the vast