Researchers have discovered for the first time that the number of electrical discharges in a spacecraft is directly correlated with the number of electrons in the surrounding environment.
Spacecraft environmental emissions (SEDs) are temporary electrical failures that can damage sensitive onboard electronics and communication systems.
Discovering information about these discharges can help scientists better understand how to protect equipment in space.
“We’ve known for a long time that these SEDs exist, but we didn’t understand the relationship between electrons and SEDs in the space environment,” commented Amitabha Nag, a scientist at the Los Alamos National Laboratory and author of a new paper detailing the research.
“To do that, a single spacecraft required two sensors: one that saw the number and activity of electrons, and the other that looked at radio frequency signals.”
What causes the spacecraft’s electrical discharge?
EDS is the result of differences in surface charging, usually caused by electrons that accumulate on orbital spacecraft surfaces.
Electrical discharges in space traffic environments are similar to static electricity on Earth, for example, when energy accumulates as a person crosses the carpet, causing sparks when a finger touches the door handle.
They are generated when the spacecraft’s energy storage reaches a sufficiently large voltage and the energy is released.
Simultaneously checking radio frequency and electronic activity
The Geostationary Orbit’s Department of Defense satellite, called the STP-SAT6, is equipped with dual sensors, providing researchers with a unique opportunity to simultaneously examine both radio frequency and electronic activity data.
“We were able to check the SED speed reported by radio frequency sensors and compare it with the activity of electronic particles within a specific voltage range,” says Nag.
“What we learned was that the peak of SED correlates with the peak of electronic activity.”
The team analyzed data from two sensors over a year. Both were developed by the laboratory and identified over 270 highly rated SED periods and hundreds of episodes of high electronic activity.
The role of electrons in causing spacecraft environmental emissions.
In about three-quarters of cases, the peak of electronic activity was 24-45 minutes prior to the SED event. This delay suggests that the accumulation of charge from low-energy electrons plays an important role in priming spacecraft for electrostatic discharge.
Nag explained: “When electronic activity increases, especially in the range of 7.9 to 12.2 keV, the spacecraft begins to accumulate charge. This process continues until you reach a tipping point, at which point the SED will occur.”
“That lead time opens the door for potential forecasting tools to mitigate risk,” he added.
In the future, the mission could integrate real-time monitoring of low-energy electrons to predict and respond to charging events before impacting operations.
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