Scientists are investigating the effects of extreme space weather on geostationary satellites with the intention of better preventing electronics failure.
In a new study published in Space Weather, researchers from the Massachusetts Institute of Technology (MIT) say that solar flares, geomagnetic storms and other forms of electromagnetic radiation may be to blame for up to 26 failures in eight geostationary satellites owned by London-based telecommunications company Immarsat that took place over 16 years of operation.
Geostationary satellites orbit at the same rate as the Earth’s rotation, which allows the satellites to maintain a constant location relative to the planet throughout their lifetime while providing access to television, Internet and communication services. Designed to last for up to 15 years, the satellites are heavily shielded to protect sensitive electronic components from solar radiation; however, say MIT researchers, over time radiation can penetrate the shielding and affect the performance of these components.
“If we can understand how the environment affects these satellites and we can design to improve the satellites to be more tolerant, then it would be very beneficial not just in cost, but also in efficiency,” Whitney Lohmeyer, a graduate student in MIT’s Department of Aeronautics and Astronautics, said. Lohmeyer and Kerri Cahoy, an assistant professor of aeronautics and astronautics, are working together to evaluate how sensitive satellite components are to the weather conditions in space, and how these conditions contribute to satellite failure.
Results from the study indicated that the majority of the Immarsat satellite failures overlapped with periods of high-energy electron activity during declining phases of the solar cycle. The researchers believe that this particle flux may have accumulated in the satellites over time, creating internal charging that damaged the amplifiers responsible for strengthening and relaying signals back to Earth. While most satellites carry back-up amplifiers, says Lohmeyer, over time this supply may run out.
“Once you get into a 15-year mission, you may run out of redundant amplifiers,” she said. “If a company has invested over $200 million in a satellite, they need to be able to assure that it works for that period of time. We really need to improve our method of quantifying and understanding the space environment, so we can better improve design.”
Today, engineers design satellites using radiation models to predict how much radiation a satellite in a particular orbital path may be exposed to during its lifetime. But these radiation models aren’t perfect, says Cahoy.
“Space weather is a lot more dynamic than models predict, and there are many different ways that charged particles can wreak havoc on your satellite’s electronics,” she said. “The hard part about satellites is that when something goes wrong, you don’t get it back to do analysis and figure out what happened.”
As users continue to demand more capabilities, engineers will need to ensure that increasingly complex satellites remain adequately protected from solar radiation. Understanding the connection between space weather conditions and the effects on satellite components will help guide these design improvements.
