The European Southern Observatory (ESO) has entered into an agreement with an international consortium, which includes the University of Michigan, to design and construct the Multi-Object Spectrograph (MOSAIC). This instrument will be installed on the 39-meter Extremely Large Telescope (ELT), set to become the world’s largest optical telescope upon completion in about four years.
MOSAIC is designed to measure light from over 200 sources at once. It will help scientists study how galaxies have grown and how matter has been distributed from the Big Bang to today.
Christopher Miller, a professor of astronomy at the University of Michigan, said, “This instrument and this telescope will be, in almost all cases, better than the JWST in terms of its power to see the distant past and in terms of its fineness of detail.”
More than 30 institutions from 13 countries are working together on MOSAIC. The University of Michigan is currently the only U.S. university participating under this agreement. Several faculty members from Michigan are involved early in planning stages, including Sally Oey, Oleg Gnedin, and Sean Johnson—who leads a scientific subgroup for MOSAIC.
Miller explained the university’s approach: “The idea was that Michigan would get involved early enough so that our faculty, our staff, our postdocs and our students would have an opportunity to be involved in building the plan to do the science.”
Unlike NASA’s James Webb Space Telescope (JWST), which operates from space and is known for its images of deep space objects, the ELT is being built on Earth in Chile’s Atacama Desert. When completed later this decade, it is expected to transform current knowledge about space. The MOSAIC spectrograph will allow astronomers to break down light into its wavelengths so they can learn about properties such as chemical composition or temperature.
Michael Meyer, professor and chair of Michigan’s Department of Astronomy, stated: “MOSAIC represents a final, and critical piece, of U-M’s investment in the ESO 39-meter ELT instrumentation program. It combines the light-gathering power of the ELT with the advantages of a multi-object spectrograph to undertake surveys that cannot be done with any other capability.”
The MOSAIC instrument aims to conduct detailed studies on matter distribution within and between galaxies. It will also examine gas around galaxies and identify their chemical elements by analyzing visible and near-infrared light across a wide field of view for more than 200 objects simultaneously.
“That’s what gets me excited. The term that we use for it is multiplexing,” Miller said. “We’re used to getting information on astronomical objects one at a time, but now we’re getting to 10 times that, even 100 times that. And out of that comes the new discoveries and new science.”
