The Giant Magellan Telescope (GMT) is a ground-based extremely large telescope under construction, as part of the US Extremely Large Telescope Program (US-ELTP), . It will consist of seven 8.4 m (27.6 ft) diameter primary segments, that will observe optical and near infrared (320–25000 nm) light, with the resolving power of a 24.5 m (80.4 ft) primary mirror and collecting area equivalent to a 22.0 m (72.2 ft) one, which is about 368 square meters. The telescope is expected to have a resolving power 10 times that of the Hubble Space Telescope and four times that of the James Webb Space Telescope, although it will be unable to image in the same infrared frequencies available to telescopes in space. , six mirrors have been cast and the construction of the summit facility has begun. A total of seven primary mirrors are planned, but it will begin operation with four. The US$1 billion project is US-led in partnership with Australia, Brazil, and South Korea, with Chile as the host country. Site The location of the telescope is Las Campanas Observatory, which is also the site of the Magellan Telescopes, some north-northeast of La Serena, Chile and south of Copiapó, Chile, at an altitude of . The site has been chosen as the new instrument's location because of its outstanding astronomical seeing and clear weather throughout most of the year. Moreover, due to the sparsity of population centers and other favorable geographical conditions, the night sky in most of the surrounding Atacama Desert region is not only free from atmospheric pollution, but in addition it is probably one of the places least affected by light pollution, making the area one of the best spots on Earth for long-term astronomical observation. Major site preparation began with the first blast to level the mountain peak on 23 March 2012. In November 2015, construction was started at the site, with a ground-breaking ceremony. The excavation for the foundations was completed in early 2019. As of August 2022, the site is ready for the pouring of the foundation's concrete. Mirrors The telescope will use seven of the world's largest mirrors as primary mirror segments, each in diameter. These segments will then be arranged with one mirror in the center and the other six arranged symmetrically around it. The challenge is that the outer six mirror segments will be off-axis, and although identical to each other, will