In our latest episode of Lexicon, we sit down with Dr. Lulu Zhao, an assistant professor of climate and space sciences and engineering at the University of Michigan and the lead of NASA’s CLEAR Center, a Space Weather Center of Excellence.
Dr. Zhao’s work focuses on one of the least understood but most impactful forces shaping modern technology. Space weather and specifically solar energetic particles affect everything from aircraft avionics to satellites to the safety of future astronauts traveling to the Moon and Mars.
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Space weather and Earth
Dr. Zhao began out talk by outlining the core of her research. “My research is all about space weather and space weather predictions,” she explained.
As head of the CLEAR Center, she leads NASA-funded efforts to create a new framework for forecasting solar energetic particles, often shortened to SEPs.
Her goal and the goal of the center are simple to describe but extremely difficult to achieve. “We are trying to build a space weather prediction framework for the solar energetic particles,” she said, adding that it is a challenge that pushes physics, computation, and AI to their limits.
Did the Sun glitch Airbus’ flight?
We next moved to ask her whether solar activity could have caused the recent Airbus software glitches. Dr. Zhao explained that high-energy radiation effects on electronics are well-documented.
“High-energy particles coming from the Sun are very well known to cause bit flips in electronic systems,” she noted. “This is already a very well-studied effect,” she added.
But, whether the Airbus event was caused by solar particles is another matter. Dr. Zhao and colleagues reviewed the data and found no major solar activity at the time.
“We did not find any large events from the Sun,” she said. Instead, she points to an ever-present cosmic ray background as the more likely culprit. “It is very possible these glitches came from cosmic rays,” she added.
The event also occurred at a low latitude, where Earth’s magnetic field is strongest. “You need very high energy particles to hit that region,” she said, which makes any single event upset at that latitude “very unlucky.”
A single particle is enough
Dr. Zhao went on to explain that even a single particle is enough to cause a problem. “One bit flip is enough to cause trouble if you hit a very critical bit,” Dr. Zhao said.
It does not require a cascade or a cluster. One stray proton or ion traveling at a fraction of the speed of light can flip a zero to a one or vice versa. “That is enough to affect a control system,” she said.
These events are rare but constant and unpredictable. “When you see this thing happen, it has already happened. The particle came and went. You cannot trace it,” she added.
To help visualize these hazards, Dr. Zhao offers a crisp explanation of what SEPs actually are. “They are very fast, very energetic particles, including protons, electrons, and heavier elements like helium, oxygen, and iron,” she told us.
To do this, Dr. Zhao explained, researchers use mega electron volts and giga electron volts because their mass is so small and their energies so large. A 400 megaelectron volt proton travels at a significant fraction of the speed of light.
“Even though the Sun is very far away from us, those particles travel very fast. The fastest ones reach Earth within about ten minutes,” she told us.
Because they are charged particles, they interact strongly with electronics. “When a charged particle hits a microchip, it deposits a tiny amount of energy into your chip, and it could flip a zero to one or one to zero,” Dr. Zhao said.
Worrying events, but rare
This phenomenon is known as a single-event upset, and it has been studied for decades. Importantly, altitude matters. “Aircraft at cruising altitude experience more particles than us on the ground because they are higher in the atmosphere,” she noted.
Satellites are even more exposed. The higher the altitude, the thinner the atmosphere and the weaker the magnetic shielding overhead.
The polar regions introduce another complication. Earth’s magnetic field offers less protection there. “The polar region is more vulnerable,” she explained.
Aircraft flying polar routes are exposed to higher radiation levels and also must contend with possible communication disruptions because “solar events disturb our environment and affect wave propagation,” she said.
Forecasting the invisible
The conversation then shifted to forecasting. SEPs are among the most difficult solar phenomena to predict. Dr. Zhao lays out the challenge clearly. “The flares and coronal mass ejections are well understood, but sometimes large ones do not produce particles, and sometimes smaller ones do,” she told us.
The relationship is neither linear nor consistent. SEPs also travel extremely fast and cannot be observed directly at the Sun because they are sparse compared to normal solar plasma.
To overcome this, the CLEAR Center combines empirical models, physics models, and AI systems. “We are integrating machine learning and AI into our space weather forecast,” Dr. Zhao explained. What’s more, she added, the logic is simple.
“The relationship between solar events and particles is so complex that we just throw the data to AI and let AI find the complex relation between input and output,” she said.
And the data volume is enormous. “The Sun is imaged at 4K by 4K resolution, at many wavelengths, every twelve minutes, for more than fifteen years,” she said.
The scale is too large for any human to analyze directly. “One person would need more than a lifetime to look at it all,” she said.
AI and computer models
Alongside AI, the center is developing a next-generation physics-based model called SOFI. “Our goal is to forecast not only if a solar energetic particle event will happen, but also how many particles will reach us and how long it will last,” she told us.
Current forecasting often provides only minutes of warning. CLEAR hopes to extend that to a full day. “Twenty-four hours is what we are aiming for,” she noted. Anything beyond that approaches the impossible.
We discuss the future of aviation safety in light of these capabilities. Dr. Zhao envisions a system akin to hurricane forecasting. “Real-time monitoring of the Sun and the buildup of prediction models can guide industry,” she said.
Such information could help airlines avoid vulnerable routes or prepare for communication disruptions. However, accuracy is essential. “We do not want to disrupt normal operations with false alarms,” she said. “Being ahead of time and being accurate is critical,” she added.
Space and beyond
As we wrapped things up, we explored how SEPs affect Moon and Mars missions. As she explained, without Earth’s magnetic shield, astronauts face significantly higher risks.
“The radiation is a big concern,” Dr. Zhao told us. “You want to survive the journey,” she added.
“For the very high energy particles, shielding is almost impossible,” she said. That makes forecasting even more vital.
Furthermore, she told us, mission planners must choose between two hazards. During solar minimum, cosmic rays are very high and extremely difficult to shield, she added.
During solar maximum, cosmic rays drop, but SEP events increase. “You get to choose which one you want to experience,” she said.
“We hope that whatever we build could benefit the entire community,” she added.