Here’s How OSC Is Creating One of the Most Powerful Telescopes on Earth

    Date Posted: 
    Tuesday, June 22, 2021

    How One of the Most Powerful Telescopes on Earth Is Being Built

    The night sky has always attracted stargazers — with naked eyes as well as high-powered telescopes — to marvel at the incomprehensible expansiveness overhead. And now, researchers at the Wyant College of Optical Sciences (OSC) are helping to build what Daewook Kim, Ph.D.,an OSC professor who specializes in optical engineering science, calls the “telescope of the future.”

    “We are trying to redefine what we can do on the ground in terms of looking at space,” Dr. Kim said.

    Intended to be one of the most powerful telescopes on Earth, the Giant Magellan Telescope (GMT) will have a primary mirror 24 meters across, and it will be about 100 times more powerful in terms of light collection capability and enable 10 times higher imaging resolution than the Hubble Space Telescope. It will be installed at the Las Campanas Observatory in Chile, a location with good viewing conditions more than 300 nights a year.

    The GMT is beyond anything we’ve yet seen on earth and belongs to a newly defined category called Extremely Large Telescope. It will collect seven to 10 times more light than any other telescope, allowing astronomers to observe dim and faint stars at the far reaches of the universe. With the GMT, they hope to better understand some of the universe’s greatest mysteries, such as how the Big Bang led to what we can see today, how the first galaxies formed and what dark matter and dark energy are.

    OSC Scientists Are Engineering the Mirror

    Backed by funds allocated from a $17.5 million grant, OSC researchers are building a key component of the GMT — the mirror. “That’s the main item, and it’s the most challenging,” Dr. Kim said. You can’t build a single mirror that big (about 24 meters in diameter)— you couldn’t transport it to the mountaintop on existing roadways. So, the team is building seven smaller mirror segments, which are still 8.4 meters in diameter and the largest individual optical mirrors ever made in history, at the Richard F. Caris Mirror Lab that, when the time comes, they will put together on site.

    Initially, no one was sure if these mirror segments could be built. It took seven years to build the first one, but now the engineers know it can be done.  

    “If we couldn’t build the first one, everything else would be meaningless,” Dr. Kim said, adding that the second one was also completed, the third one is now nearing the completetion, and the remaining four are moving through the production process.


    Optical Tests for Superb Accuracy

    One of the most challenging aspects of building the mirrors is getting the surface perfectly shaped and smooth — it may not be deviated by more than 20 nanometers.

    “That’s not easy,” Dr. Kim said, “but that’s the fabrication technology we are doing here.”

    OSC researchers are conducting optical testing and manufacturing by accurately measuring the surface to guide the polishing process. The fabrication process uses a substance that’s solid and liquid at the same time, like Silly Putty, to smooth out surface shape fluctuations. The Universtiy of Arizona team is also building a test bed system so they can check the telescope’s adaptive optics system before the telescope is assembled on the mountaintop in Chile.

    The timeline isn’t definite, but Dr. Kim believes the telescope will be up and fully running in this decade.

    “Nothing has ever existed before on this scale,” Dr. Kim said. “As a scientist and engineer building these systems, it’s exciting to think we’ll be able to travel back in time all the way to the very close moment after the Big Bang by imaging ultra deep fields more than 13 billion light years aways from Earth.”

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