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Constructing the World’s Largest Optics: The Giant Magellan Telescope’s Final Mirror Fabrication Begins

Artist’s concept of the completed Giant Magellan Telescope. The Giant Magellan Telescope is finalizing its last primary mirror, with the goal to surpass current space telescopes in sensitivity and resolution. Leveraging U.S. manufacturing, it promises unparalleled astronomical insights and aims for operation by the decade’s end. Credit: GMTO Corporation

Seven of the world’s largest mirrors will search the Universe for life beyond Earth

The Giant Magellan TelescopeWhen completed, the Giant Magellan Telescope (GMT) will be a member of the next class of giant ground-based telescopes that promises to revolutionize our view and understanding of the universe. It will consist of seven 8.4-meter mirrors that will observe optical and near-infrared light, with an effective aperture 24.5 meters in diameter. The Giant Magellan Telescope is expected to have a resolving power 10 times greater than the Hubble Space Telescope.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>Giant Magellan Telescope begins the four-year process to fabricate and polish its seventh and final primary mirror, the last required to complete the telescope’s 368 square meter (3,961 square foot) light collecting surface, the world’s largest and most challenging optics ever produced. Together, the mirrors will collect more light than any other telescope in existence, allowing humanity to unlock the secrets of the Universe by providing detailed chemical analyses of celestial objects and their origin.

Giant Magellan Telescope Seventh Mirror Final Glass Placement

University of Arizona Richard F. Caris Mirror Lab staff member placing final chunks of Ohara E6 low expansion glass into a mold for casting primary mirror segment seven, September 2023. Credit: Damien Jemison, Giant Magellan Telescope –GMTO Corporation

Unique Glass Melting Technique Underway

Last week, the University of Arizona Richard F. Caris Mirror Lab closed the lid on nearly 20 tons of the purest optical glass inside a one-of-a-kind oven housed beneath the stands of the Arizona Wildcats Football Stadium. The spinning oven will heat the glass to 1,165°C (2,129°F) so as it melts, it is forced outward to form the mirror’s curved paraboloid surface. Measuring 8.4 meters (26.7 feet) in diameter—about two stories tall when standing on edge—the mirror will cool over the next three months before moving into the polishing stage.

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The Giant Magellan Telescope begins the four-year process to fabricate and polish its seventh mirror, the last required to complete the set. Credit: Giant Magellan Telescope – GMTO Corporation, OJO Entertainment, NASAEstablished in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. Its vision is "To discover and expand knowledge for the benefit of humanity." Its core values are "safety, integrity, teamwork, excellence, and inclusion." NASA conducts research, develops technology and launches missions to explore and study Earth, the solar system, and the universe beyond. It also works to advance the state of knowledge in a wide range of scientific fields, including Earth and space science, planetary science, astrophysics, and heliophysics, and it collaborates with private companies and international partners to achieve its goals.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>NASA, University of Arizona

At 50 million times more powerful than the human eye, “the telescope will make history through its future discoveries,” shares Buell Jannuzi, Principal Investigator for the fabrication of the Giant Magellan Telescope primary mirror segments, Director of Steward Observatory, and Head of the Department of Astronomy at the University of Arizona. “We are thrilled to be closing in on another milestone in the fabrication of the Giant Magellan Telescope.”

Giant Magellan Telescope Seventh Primary Mirror Glass Placement

University of Arizona Richard F. Caris Mirror Lab staff members placing nearly 20 tons of Ohara E6 low expansion glass into a mold for casting the Giant Magellan Telescope’s seventh primary mirror segment, September 2023. Credit: Damien Jemison, Giant Magellan Telescope – GMTO Corporation

Integration and Testing

The most recently completed primary mirror is ready for integration into a giant support system prototype early next year for final optical performance testing. This testing will serve as the dress rehearsal for all seven primary mirrors. Once assembled, all seven mirrors will work in concert as one monolithic 25.4-meter mirror—a diameter equal to the length of a full-grown blue whale—resulting in up to 200 times the sensitivity and four times the image resolution of today’s most advanced space telescopes.

The Giant Magellan Telescope will be the first extremely large telescope to complete its primary mirror array. With strong operational infrastructure completed at the telescope site in Chile, focused manufacturing is taking place on the telescope’s critical subsystems before starting on the enclosure.

Giant Magellan Telescope Interior Rendering

Sunlit daytime interior telescope rendering of the Giant Magellan Telescope. Credit: GMTO Corporation

“We are in an important stage of fabrication, with much of the manufacturing happening in the United States,” shares Robert Shelton, President of the Giant Magellan Telescope.

The 39-meter-tall telescope structure is being manufactured with 2,100 tons of American steel at a newly built manufacturing facility in Rockford, Illinois, and fabrication of the telescope’s first of seven adaptive secondary mirrors—a one-for-one pair with each of the seven primary mirrors—is underway.

Giant Magellan Telescope Seventh Primary Mirror Mold and Glass Placement

University of Arizona Richard F. Caris Mirror Lab staff members placing chunks of Ohara E6 low expansion glass into a mold for casting the Giant Magellan Telescope’s seventh primary mirror segment, September 2023. Credit: Damien Jemison, Giant Magellan Telescope – GMTO Corporation

Promising Capabilities and Expectations

“The combination of light-gathering power, efficiency, and image resolution will enable us to make new discoveries across all fields of astronomy,” shares Rebecca Bernstein, Chief Scientist for the Giant Magellan Telescope. “We will have a unique combination of capabilities for studying planets at high spatial and spectral resolution, both of which are key to determining if a planet has a rocky composition like our Earth, if it contains liquid water, and if its atmosphere contains the right combination of molecules to indicate the presence of life.”

The telescope is expected to see first light by the end of the decade, and will work to answer some of humanity’s most pressing questions: Where did we come from? Are we alone in the Universe?

Source: SciTechDaily