ATLANTA—The U.S. Air Force has awarded Georgia State University astronomy professor Stuart Jefferies a grant of nearly a million dollars to develop a technique to detect and characterize satellites in greater detail than ever before.
The new technique could have implications for astronomers trying to spot small, dim objects hidden in the light of companions, and could assist the government in monitoring space junk that can pose a threat to U.S. satellites as well as keeping an eye on foreign satellites.
The new method should make it easier to spot smaller, dimmer satellites hovering in the shadows of their larger, brighter neighbors and determine their composition, revealing how they aged in space.
Satellites with larger surface areas reflect more sunlight, making them easier to spot. Their light can easily drown out dimmer neighboring satellites. For instance, a communication satellite the length of a football field can overpower a nearby, laptop-sized satellite used for research.
“It’s like me standing next to a floodlight in a football stadium with a tiny flashlight, and you trying to see the flashlight,” Jefferies said.
Traditionally, researchers collect light in a single visible wavelength, often closer to red than blue because bluer light receives more atmospheric interference. But the process isn’t ideal; the redder light provides less resolution than blue light, revealing less detail about the target. By collecting light from every visible wavelength, Jefferies’ team plans to unpack the collected information to reveal insights about the satellite, including details about its shape and composition.
“The fact that we’re using all the light gives us a better chance of seeing it than if we were just using a small, narrow band of light,” Jefferies said.
Blue light provides more detail but is more affected by atmospheric interference than red light. The new instrument will rely on the fact that light is broken into its component pieces by the atmosphere to allow the researchers to determine the composition of the target.
“The atmosphere and the instrument combine to make a natural spectrometer for us,” said Jefferies, referring to the instrument that allows researchers to probe the properties of a target emitting light.
The team’s first priority is to identify faint satellites that have remained previously unseen. Then they hope to learn more about the what the satellite is made of, which can provide insights into what it can accomplish. For instance, a satellite with a large area covered by solar panels can generate significant power, allowing researchers to offer an assessment of what it might be capable of. Similarly, its orbit — whether hovering over a single location on Earth or circling between our planet and the moon — can also provide clues about its purpose.
The technique won’t be limited to identifying other types of satellites. By studying the Air Force’s own orbiting targets, with known ages and compositions, Jefferies will monitor how materials degrade in space due to radiation and micrometeorite damage. These observations will allow the Air Force and other agencies to monitor the health of their satellites. At the same time, understanding how the material degrades will help identify the makeup and purpose of previously unknown satellites.
“[These observations] should be enough to tell us about the different materials of artificial satellites,” Jefferies said. “If we can do that, it would be a huge gain.”
The entire system is simple and can be placed on any telescope system. As part of the three-year grant, the team will develop a sensor capable of collecting multi-wavelength data. The larger the telescope, the smaller and more distant objects can be detected. The team’s recent work with the Air Force has demonstrated their ability to detect objects 10,000 times dimmer than their neighbors but Jefferies thinks they can identify objects as much as a million times fainter. That contrast can help researchers hunt for planets outside the solar system that might be drowned out by the light of their star.
The team has already engaged in numerical simulations to determine that the process is feasible. For proof of concept, they will test their instrument using an atmospheric turbulence simulator in the laboratory. The sensor will then be tested on a brand-new telescope at Georgia State’s Hard Labor Creek Observatory in Morgan County to observe a known satellite and determine how well the new technology can correctly identify the composition of the target. Other telescopes will also be used.
Jefferies is working with Dmitriy Shcherbik, a Research Engineer at Georgia State, and astronomy Ph.D. students, Ryan Hall and Fallon Konow.