The University of Arizona has signed a three-year, $8.6 million cooperative agreement with the U.S. Space Force to develop a new imaging system that will advance space domain awareness, or SDA – the ability to monitor and understand objects and activity in space.

The Strategic Space Technology Institute for Ultra-High-Resolution Imaging at Millimeter Wavelengths, or SURe, will expand a network of ground-based antennae, or radio telescopes, and improved data analysis methods to detect and image satellites in orbit around the Earth.

"For decades, the University of Arizona has redefined how we explore the farthest reaches of space – from mapping the moon and Mars to helping capture the first image of a black hole," said Tomás Díaz de la Rubia, senior vice president for research and partnerships. "Now, in partnership with the U.S. Space Force, we are applying those same world-class capabilities closer to home. We are adapting our astronomical tools used for studying distant objects to enable observations of the dynamic environment of satellites orbiting the Earth. We are delivering unprecedented clarity in support of national security. This effort shows that our legacy of discovery is not only about exploration – it is essential to the nation's safety and long-term strategic strength."

High-tech eyes on objects in orbit

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The number of satellites in orbit around the Earth is rapidly growing, said Christopher Walker, U of A astronomy professor and director of the SURe project. Thousands more satellites are expected to be launched into space by 2030, exacerbating congestion, the potential for collisions and competition that can endanger other spacecraft and human spaceflight and pose national security threats in various orbits between Earth and the moon.

Low Earth orbit, or LEO, encompasses Earth-centered orbits with an altitude below 1,200 miles and is the area in which the International Space Station resides. Medium-Eart orbit, or MEO, stretches from about 1,243 to 22,236 miles above sea level and is commonly used for navigation systems, including GPS. Geosynchronous orbit, or GEO, is a very high orbit that is ideal for certain kinds of communication satellites and meteorological satellites. Objects orbiting in GEO travel at the same rate and direction as the Earth's spin on its axis.

The SURe team will gather images of satellites using multiple radio antennae, some mobile, some on permanent sites. Working together, the radio antennae are known as the Arizona Array, and their diameters range from the length of a couch to that of a house – 2 meters, 6.1 meters, 10 meters and 12 meters.

The array uses very long baseline interferometry to generate high spatial resolution images of observed satellites. By simultaneously observing the radio emission from a satellite with multiple widely separated antennae, astronomers can create an image with the same spatial resolution of a much larger antenna with a diameter as large as the separation of the most widely separated antenna used in the array.

Researchers traditionally have used this technique to study extremely distant objects, including the event horizon of a supermassive black hole. The SURe team will adapt this method to observe objects much closer, such as satellites orbiting the Earth.

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To interpret the resulting signals, the team will use software and analysis techniques developed at the U of A. This method compares the radio waves received at each antenna, correcting for differences in timing and angle caused by their separation, and reconstructs the satellites' shapes, orientations and surface features with a level of detail far surpassing what any single antenna of practical size could provide.

"By looking at the differences in what each antenna detects, we can reconstruct what an image of the satellite would look like if it had been observed by a really giant antenna or telescope," said U of A principal investigator Buell Jannuzi, director of Steward Observatory and head of the Department of Astronomy.

"SURe's novel approach of combining millimeter-wave interferometric techniques with near-field correction and target illumination offers the potential for transformative change in the ability to detect, image and monitor objects in LEO, MEO and GEO," Walker said. "We'll achieve high-resolution imaging, day or night, even in poor weather conditions – capabilities that traditional optical telescopes or radar cannot provide."

Uniquely equipped

The Space Force funded SURe through the Space Strategic Technology Institute 4, a program that creates new technologies by transitioning academic research into practical applications and operates within a University Consortium of government, academic and industry partners.

The SURe project team includes University of Massachusetts Lowell and University of Virginia, with the work anchored in Tucson. Industry collaborators are Tucson companies FreeFall Aerospace Inc. and Rincon Research Corp., as well as DA2 Ventures in Fort Collins, Colorado, and Virginia Diodes in Charlottesville, Virginia.

 "The U of A is uniquely capable of leading this effort," Walker said. "Together with our academic and industry partners, our team has the expertise to carry this off."

The U of A is ranked No. 2 in the 2024 National Science Foundation Higher Education Research and Development Survey of research dollars expended in astronomy and astrophysics, and No. 4 in the world in U.S. News and World Report 2025 space science rankings.

Walker has guided major NASA efforts, including the $50 million NASA Explorer mission GUSTO, a long duration balloon-borne observatory that flew above Antarctica for 57 days to map the interstellar medium of our galaxy – the gas and dust that fill the space between stars – providing data that helps scientists study how stars and galaxies form.

"SURe marks the first time Steward Observatory has applied its astronomy expertise in partnership with the U.S. Space Force," Jannuzi said. He added that the work aligns with Steward's long history of working with federal agencies to support scientific research and national security space needs.

"It's great to see this new partnership developing, highlighting how transformational research can impact not just basic science but also national interests," he said. "This work brings in funding from outside the state as part of the space science enterprise at the University of Arizona. Space science at the U of A generates more than $560 million annually in direct economic impact for the state."