Based on data gathered by the sensors aboard the US Department of Defense Space Test Program Satellite 6 (STP-SAT6), we discovered a direct correlation between the frequency of electrical discharges on a spacecraft and the electron density in its environment.

Spacecraft environmental discharges (SEDs) are short-lived electrical failures that may harm sensitive onboard electronics and communication systems.

While researchers have acknowledged the presence of SEDs for some time, the relationship between spatial environments and their electrons remains unclear.

“To explore this, we required two sensors on the same spacecraft: one to monitor electron quantity and activity, and another to detect radio frequency signals,” explained Dr. Amitabh Nag, a researcher at Los Alamos National Laboratory.

SEDs arise from variations in surface charging, typically due to the accumulation of electrons on the surfaces of orbiting spacecraft.

This process differs from static electricity on Earth. For instance, when someone walks across a carpet and discharges static after touching a door handle, a buildup of energy occurs. Likewise, when a spacecraft’s energy storage reaches a critical voltage, it results in an electrical discharge in space.

The STP-SAT6 is fitted with both sensors, allowing a unique opportunity for researchers to analyze both radio frequency and electronic activity simultaneously.

“We managed to assess the speed of SEDs as reported by the radio frequency sensors and compare it with the electronic particle activity within specific voltage ranges,” Dr. Nag noted.

“Our findings indicated that the peak of SEDs coincides with the peak of electronic activity.”

The authors analyzed data from two sensors over a year-long period, identifying heightened electronic activity during 270 high-speed SED occurrences and numerous episodes.

In roughly three-quarters of instances, the peak in electronic activity occurred 24-45 minutes before the SED event.

This delay implies that the buildup of charge from low-energy electrons plays a crucial role in preparing the spacecraft for electrostatic discharge.

“We noted that as electronic activity increases, the spacecraft begins to gather charges, especially in the 7.9-12.2 keV range,” Dr. Nag added.

“This process continues until a tipping point is reached, resulting in an SED.”

“Such lead time presents an opportunity for potential forecasting tools to reduce risks.”

“Future missions could include real-time monitoring of low-energy electrons to predict and react to charging events before they disrupt operations.”

The results will be published in the journal Advances in Space Research.

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Amitabag et al. 2025. Radio frequency transients correlated with electronic flux installed in STP-SAT6. Advances in Space Research 76 (6): 3692-3699; doi: 10.1016/j.asr.2025.07.026