University Of Michigan Joins Team To Build MOSAIC, A 200-Target Spectrograph For The World's Most Powerful Telescope

The University of Michigan has been named one of two U.S. institutions contributing to the design and construction of MOSAIC, a major new instrument for the European Southern Observatory’s Extremely Large Telescope (ELT), the ESO announced last week.

MOSAIC (Multi-Object Spectrograph) will be capable of measuring light from more than 200 sources simultaneously, enabling astronomers to collect spectra for many objects at once. That multiplexing ability promises to accelerate discoveries about galaxy formation, chemical composition and the distribution of matter after the Big Bang.

The ELT, currently under construction in Chile’s Atacama Desert, is expected to be completed and begin scientific operations later this decade. Once operational, it is anticipated to be the most powerful ground-based optical telescope and will complement — and in certain observational modes surpass — space telescopes such as NASA’s James Webb Space Telescope in resolution and deep-universe sensitivity.

"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," said Christopher Miller, a University of Michigan astronomy professor.

The European Southern Observatory said: "When it sees first technical light later this decade, the ELT will revolutionize what we know about our universe and make us rethink our place in the cosmos."

A spectrograph like MOSAIC splits incoming light into its component wavelengths (a spectrum). Astronomers use spectra to infer key physical properties of celestial objects — for example, their temperatures, velocities and chemical make-up — information that imaging alone cannot provide.

According to Miller, MOSAIC’s multiplexing will change how surveys are done: "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."

The project’s U.S. partners are the University of Michigan and the Space Telescope Science Institute in Baltimore. In addition, 31 institutes across 12 countries are contributing expertise to MOSAIC and other ELT instruments.

Construction of the ELT is already under way in the Atacama Desert in Chile. MOSAIC is one of several instruments being designed to equip the telescope for a wide range of studies, from probing the early universe to mapping galaxy evolution.

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