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Sean Peters is leading a major multi-institutional initiative to develop power efficient passive radar systems that could peek under the surface of Mars.

Peters has earned a $2.45 million, three-year NASA grant to create a drone-based system to map subsurface areas. The project includes field-testing on Earth with an eye toward potential future deployments on missions to the red planet. The work will be carried out in collaboration with NASA’s Jet Propulsion Laboratory, the University of Arizona, and the Reykjavik University in Iceland.

“This will allow us to understand the properties of the surface, the depth of ice deposits, and areas that have potential for astro-biological studies on indicators that may support life” said Peters, an assistant professor in the Ann and H.J. Smead Department of Aerospace Engineering Sciences at the University of Colorado Boulder.

Utilizing radar on a drone presents unique challenges, and Peters’ team has ideas how to solve this challenging problem.

Most radar technology actively transmits signals, sending out pings and tracking the response to map nearby terrain or objects. This technology has been applied to various industries, such as military, air traffic control, and the geosciences.

Aboard a drone, such systems are not always practical, as they are large and power hungry.

Peters has proposed a much smaller passive radar system that, instead of emitting its own signals, would pick up natural electromagnetic waves emitted by the sun and Jupiter to conduct measurements.

“You’re listening for radio noise, essentially the unwanted part in a traditional active radar, to implement this low-resource technology onboard an uncrewed aerial system for altimetry and sounding,” Peters said. “We’ve done preliminary tests with the sun, and we know this is possible. It should be possible for Jupiter too.”

Taking advantage of ambient radio waves from radio-astronomical bodies was a focus of Peters’ PhD thesis and has been an area of active work for nearly a decade at NASA’s Jet Propulsion Laboratory, which is a partner on the grant.

“Jupiter produces radio bursts at the same frequencies as traditional ground penetrating radars, and we can measure them here on Earth. They penetrate into the ground, and our goal is to pick up and analyze the reflected signals to observe what’s below the surface,” Peters said.

Peters’ PhD student, Thorsteinn Kristinsson, is conducting early work on the grant.

“We feel electromagnetic waves coming from the sun just going outside. You wouldn’t think looking at the sky that there are waves hitting your body from Jupiter too, but at certain times there are.”

The project is incorporating both the sun and Jupiter because their electromagnetic waves cover different areas of the frequency spectrum. Jupiter’s waves are lower frequency and penetrate deeper into the ground, allowing the team to conduct additional subsurface analysis.

The team will design and build the radar system and conduct initial field-testing on the ground in California within the next year. By the third year of the grant, the radar system will be incorporated into a drone for flight tests in Iceland, which has terrain analogous to Martian volcanoes.

The Iceland portion of the grant is particularly exciting for Kristinsson, who grew up there and has conducted previous research in the same area.

“It’s amazing. It gives me the opportunity to do work in my home country and field testing in an environment I know, and that is also so beautiful to be in,” Kristinsson said.