UT-Austin and Giant Magellan Telescope Organization begin casting fifth of seven mirrors

Kevin Dural

Weighing upwards of 150 tons and 25 meters in diameter, the Giant Magellan telescope will not be your average backyard telescope.

In early November, UT-Austin joined other universities to initiate the casting of the fifth of seven mirrors for the Giant Magellan Telescope at the University of Arizona. Once it is put together in 2023, the telescope will ultimately be located in the Las Campanas Observatory in Chile.

UT-Austin is a member of an international consortium of universities and organizations that includes the Australian National University, Carnegie Institution for Science, Texas A&M University and the University of Chicago. Taft Armandroff is the director of the McDonald Observatory at UT-Austin and is also the vice chair of the Giant Magellan Telescope Organization (GMTO) Board.

“With this next milestone, and with the leadership, technical, financial and scientific prowess of the members of the GMTO partnership, we continue on the path to the completion of this great observatory,” Armandroff said in a press release.

Upon completion, the Giant Magellan Telescope can provide resolution that is up to 10 times greater than that of the Hubble Space Telescope, according to GMTO president Robert Shelton. As a result, it will allow direct observation of distant planets, enabling a potential discovery of extraterrestrial life.

“Looking to the operation of the (Giant Magellan Telescope), we can say for certain that there will be discoveries we cannot imagine,” Shelton said. “That said, we do know that astronomers will focus on the earth-like planets to analyze the spectra of their atmospheres looking for biochemical signs of life.”

Shelton added that the telescope will allow scientists to essentially look back in time to understand the formation of the first stars and galaxies. It can also provide insight into black holes, dark matter and energy, the origin of chemical elements and how planets initially formed, according to the press release.

“When completed, this one-billion-dollar observatory will enable astronomers to answer some of the most fundamental questions of all: Where did we come from, and are we alone in the universe?” Shelton said. “The project to build the Giant Magellan Telescope reaches well beyond any previous ground-based observatory in complexity and promise for discovery.”

“The size and complexity of the telescope translates into lengthy stages of production,” Shelton said. “For example, the creation of each of the seven primary mirrors can take eight years.”

The complex process of preparing each mirror begins with extensive designing and planning. Next, follows ordering the approximately 20 tons of specialized glass. To cast the mirror, the glass is melted in a spinning furnace, then cooled and polished.

Shelton added that testing the telescope is an essential and rigorous undertaking. Each primary mirror will be 8.4 meters in diameter. The final steps include moving the mirrors to the Andes Mountains in Chile and, ultimately, constructing the telescope.

“The telescope mount, about 48 meters total in height, that holds the mirrors and the sophisticated instruments that turn observed light into scientific discoveries is an engineering marvel,” he said. “Finally, the dome structure will be the size of a 22-story building that rotates.”

Most of all, Shelton said that he is excited for what the future holds.

“Things will come up that we can’t even anticipate,” Shelton said.