Making an Impact by Avoiding an Impact

In 2013, an asteroid about 20 meters in diameter entered Earth’s atmosphere and exploded above the city of Chelyabinsk in Russia. The shockwave from this explosion shattered windows across several cities and injured 1,500 people.

This asteroid was not detected until it was already in the Earth’s atmosphere because it was traveling from the direction of the sun, an area of the sky where telescopes are blinded by glare.

Typical asteroid impact speeds range from 22,000 to 160,000 miles per hour, meaning that relatively small asteroids carry immense energy. Though most burn up before they reach the Earth’s surface and cause little to no damage, some—like the Chelyabinsk asteroid—can be devastating. Larger asteroids, with diameters exceeding 140 meters, have the potential to cause continental-scale damage.

Researchers in the laboratory of Daniel Scolnic, associate professor of physics and of electrical and computer engineering, are working hard to improve early asteroid detection for planetary defense.

Qifeng Cheng, a doctoral student in Scolnic’s lab, uses simulations of synthetic impactors to assess how well the world’s most powerful ground-based telescope can discover asteroids before they hit. The telescope, located at the newly established Vera C. Rubin Observatory in Chile, began operations last year.

“My work builds large synthetic Earth-impacting populations and propagates them through realistic survey simulations to quantify detection efficiency and warning times as well as explain why they’re missed,” Cheng said.

Braxton Townsend, a first-year undergraduate student majoring in physics, works with Cheng to develop a program that calculates the potential dates that an asteroid might impact Earth as well as the probability of the impact occurring. “This will allow us to better understand the risk that an asteroid poses and evaluate if action is needed to prevent a collision,” Townsend added.

The Rubin telescope is designed to see more deeply into space than other ground-based telescopes. This means that it can detect faint objects—like distant asteroids—that might otherwise be missed. Cheng’s work predicts that Rubin can detect large impactors months to years before they reach Earth.

Although Rubin is extremely powerful, it is not designed solely for asteroid detection; it serves other purposes like understanding dark matter and energy. These competing priorities introduce trade-offs. A key limitation of Rubin in the context of asteroid detection is its cadence—that is, how frequently it captures an image of a particular region of space.

But combining Rubin with complementary systems could improve its application to early asteroid detection. One such system is the Argus Array, a network of 1,200 telescopes poised to image the entire sky, beginning in 2027. The Argus Array is a high-cadence system, meaning that it can capture multiple images of the same region very quickly. This allows scientists to link successive detections of the same impactor. If detections are too far apart in time, as in lower cadence systems, it becomes difficult to track the movement of a single object, and separate detections are considered “unlinked.”

Asteroids coming from the direction of the sun, like the Chelyabinsk, are difficult to detect because they appear very faintly and for short periods of time. Combining Rubin with the Argus Array will allow astronomers to detect these asteroids sooner, capture multiple images in a short time and link them to map unique trajectories.

“Rubin excels at detecting faint objects and refining orbits, while Argus increases the chance of noticing fast-moving or short-lived objects as soon as they become visible,” said Cheng.

An asteroid is considered “discovered” when multiple detections link to a single, unique object. The next steps are to refine the orbit of the asteroid and calculate the probability and severity of impact. An important step in this process is determining the distance of the asteroid from Earth. Maryann Benny Fernandes, a PhD student also in Scolnic’s lab, uses a technique called topocentric parallax to determine asteroid distances based on the Earth’s daily rotation.

As Fernandes puts it, “When an asteroid is observed over a single night, its intrinsic motion is nearly linear, while Earth’s rotation introduces a small but predictable sinusoidal signal in its apparent position.”

Fernandes models this combined motion to determine the distance of the asteroid from Earth. Combining observations from multiple ground-based telescopes will make these models more accurate. But determining asteroid position can also be confounded by the refraction, or bending, of light as it enters Earth’s atmosphere. This can shift the apparent position of an asteroid and introduce errors in predicted impact zones. Fernandes, along with high school student Nikhil Nanduri from the North Carolina School of Science and Mathematics, study how to account for atmospheric refraction in observations.

Once an asteroid is detected and characterized, what can be done to prevent a catastrophic collision? If the risk is significant, the asteroid can be deflected by sending a spacecraft to alter its orbit by crashing into it.

“This is where public policy and space law become central, determining who has the authority to act, who is responsible for which actions, how international coordination happens, and how risk information is communicated and used,” said Cheng.

Scolnic’s team recently launched a Bass Connections project to develop an asteroid impact risk assessment tool to inform policy decision-making. Scolnic also serves as director of the Science and Policy to Advance Cosmic Exploration (SPACE) Initiative at Duke, alongside Michael Troxel, associate professor of physics at Duke. This initiative, established in 2025, aims to build interdisciplinary collaboration across Duke to advance space exploration and policy.

An important part of advancing our understanding of space is getting people excited about it. Outside of research, Cheng uses her technical skills to create interactive digital art inspired by physics and astronomy. In one piece titled, “Sensing the Invisible: Breathing Life into the Universe,” participants breathe into a humidity sensor to produce a colorful simulation of a star radiating dynamic flares. Cheng’s art has been featured at the Astronomy Days event at the North Carolina Museum of Natural Sciences, the Expressive + WICED event at the University of London and the Boston Museum of Science.

Ruth Verinder is a biomedical engineering doctoral student working in the laboratory of Jonathan Viventi.