By Steve Koppes
Photo courtesy of Giant Magellan Telescope - GMTO Corp

Larger telescopes allow us to look farther out in space and further back in time to probe the very earliest history of the universe.”
—Edward “Rocky” Kolb
Arthur Holly Compton Distinguished, Service Professor

Most of the starlight that hits the Earth falls into the oceans, “but coded into that light is the entire history of the universe.”

So said Patrick McCarthy, project director of the Giant Magellan Telescope, during a recent visit to campus. The telescope, which could open as early as 2019, will peer more deeply into the universe’s hidden history than humans have ever attempted. Scientists say the instrument’s combined mirrors will be sensitive enough to detect a candle on the moon, or to see the face on a dime 200 miles away.

The possibilities have energized researchers at the University of Chicago, which is a founding member of the GMT Organization. Construction of the telescope will begin at the Las Campanas Observatory in Chile in two years. Experts say the facility is part of a long-term ambition to understand the nature of dark matter and dark energy, and to glimpse the formation and evolution of extrasolar planets, stars, galaxies, and black holes.

“When we study the evolution of the universe we can use telescopes as time machines,” says Edward “Rocky” Kolb, chairman of UChicago’s Department of Astronomy & Astrophysics and the Arthur Holly Compton Distinguished Service Professor. “Larger telescopes allow us to look farther out in space and further back in time to probe the very earliest history of the universe.”

In addition to joining the GMT Organization in July, UChicago also secured access for its astronomers to the existing twin Magellan Telescopes at Las Campanas, perched high in the Chilean Andes, starting next year.

“The Magellan Telescopes will be our tool in optical astronomy for the next 10 years. Beyond that is the Giant Magellan Telescope,” says Kolb.

The GMT will combine seven 8.4-meter primary mirror segments operating together as if they were part of a single, 24.5-meter telescope. Its capabilities will exceed those of even the Hubble Space Telescope.

The Search for ‘Missing Matter’

The first of the GMT’s primary mirrors has already been cast and is undergoing polishing at the University of Arizona’s Steward Observatory Mirror Lab. “There’s only one place in the world that can make these mirrors, and that’s the University of Arizona Mirror Lab,” Kolb says.

The GMT will address some of the biggest questions in astronomy, including how dark matter affects the movements of galaxies and galaxy clusters, and the role that dark energy has played in the evolution of the universe.

“We know that the universe is made of 74 percent dark energy, 22 percent dark matter, and 4 percent ordinary matter,” says Hsiao-Wen Chen, Assistant Professor in Astronomy & Astrophysics. Chen is especially interested in the search for “dark” ordinary matter. This is the stuff of stars, planets and people, yet two-thirds of this dark matter remains missing.

“The missing matter underscores a serious shortfall in our knowledge of the growth of the visible universe,” says Chen, who has made many trips to Las Campanas to use the twin 6.5-meter Magellan Telescopes for her research.

Space: Not empty

“Even though space appears to be empty, it’s not. How much more unseen matter is out there? How fast are the stars forming in the ‘dark’ universe? Will these faint objects eventually be captured by other known luminous galaxies?” Chen asks. “More powerful telescopes will help us to answer many of these outstanding questions.”

Michael Gladders, Assistant Professor in Astronomy & Astrophysics, is another frequent UChicago visitor to Las Campanas. He built two instruments for the Magellan Telescopes as a fellow at the Carnegie Institution for Science before coming to UChicago a few years ago. He and his UChicago colleagues are now discussing instrumentation possibilities for the GMT.

The GMT partners have half a dozen instrument concepts currently under study and will select up to four of them for further development in fall 2011. As a founding partner of the GMT, UChicago will have an opportunity to help select and develop the new instruments.

These instruments are specialized attachments designed to enhance the investigation of various phenomena—searching for Earthlike planets around other stars, for example. “The opportunity to build instruments for a world-leading facility like this basically opens up scientific pathways that you cannot otherwise open,” Gladders says.