Excavation begins for Giant Magellan Telescope observatory

An artist’s impression of the Giant Magellan Telescope at the Las Campanas Observatory in Chile’s Atacama Desert. Image: GMTO

Using hydraulic drills and hammers, excavators have started digging out rock to make way for the foundation and pier that eventually will support the Giant Magellan Telescope atop the 2,500-metre (8,200-foot) Las Companas peak in the Atacama Desert in Chile. Engineers expect to haul away 5,000 cubic metres (13,300 tons) of rock from the site, the equivalent of 330 dump truck loads of debris.

“With the start of construction of the permanent buildings on the site, the GMT is showing tangible progress towards completion,” said James Fanson, the Giant Magellan Telescope Organisation – GMTO – project manager.

The Giant Magellan Telescope will use seven 8.4-metre (27.6-foot) mirrors mounted in a steel telescope structure seated on a concrete pier, tipping the scales at some 1,600 metric tons.

The telescope will be housed in a rotating enclosure 65 metres (213 feet) tall and 56 metres (184 feet) wide. Mineria y Montajes Conpax, an engineering firm that has carried out site work at other observatories in the region, is responsible for digging out the foundation using jack hammers, not explosives, to make sure the rock below the foundation remains intact.

Along with work on the telescope enclosure, pier and foundation, Conpax also will excavate a recess for the lower portion of a mirror coating chamber and the foundation for a nearby utility building.

Excavators are carefully removing rock for the Giant Magellan Telescope’s foundation and pier to ensure rock below the structure remains undamaged and stable. Image: GMTO

Once in operation, the Giant Magellan Telescope will join a new wave of giant observatories that promise to revolutionise ground-based astronomy, producing infrared images 10 times sharper than those from the Hubble Space Telescope. Five of the Magellan’s huge mirrors already have been cast at the Richard F. Caris Mirror Lab at the University of Arizona.

“The GMT has a unique design that offers several advantages,” the GMTO writes on its web page. “It is a segmented mirror telescope that employs seven of today’s largest stiff monolith mirrors as segments. Six off-axis 8.4 meter or 27-foot segments surround a central on-axis segment, forming a single optical surface 24.5 meters, or 80 feet, in diameter with a total collecting area of 368 square meters. The GMT will have a resolving power 10 times greater than the Hubble Space Telescope.”

First light is expected in 2024.