LOGAN, Utah — A new solar activity cycle that may be stronger than forecast poses challenges for smallsat operators keeping their spacecraft in orbit and functioning.
During a panel discussion organized by the Secure World Foundation at the 36th Small Satellite Conference here Aug. 8, a space weather expert warned that the relatively benign conditions of the last several years are ending.
“Whatever you’ve experienced in the past two years doesn’t matter,” said Tzu-Wei Fang, a space scientist at NOAA’s Space Weather Prediction Center (SWPC). “Whatever you learned the past two years is not going to apply in the next five years.”
One effect of increased space weather activity is more drag on satellites as storms heat and expand the upper atmosphere, increasing its density. That was illustrated in February when a solar storm caused 38 of 49 newly launched SpaceX Starlink satellites to reenter when those satellites’ thrusters could not overcome the enhanced atmospheric drag created by the storm.
“That storm was actually a minor storm in our catalog. It’s not a huge storm,” she said. SWPC has been working with SpaceX to study that incident, including how models of space weather can be better used to predict atmospheric conditions than can affect satellites. A paper summarizing those findings will be published in a journal soon.
In addition to evaluating models, she said SpaceX is providing orbit data from its Starlink satellites. “We’re trying to see how we can utilize this data to improve the density estimations.”
Increased atmospheric drag has implications for space traffic management as well. “After one storm, in two days everything goes everywhere,” she said, as drag effects vary among satellites and debris. “That’s the time to start worrying about collisions.”
This rise in solar activity not only coincides with a sharp increase in the number of satellites launched, but also comes after the previous 11-year cycle, called Cycle 24 by space scientists, that was relatively mild. That means many satellite operators aren’t experienced with the impacts of an active sun.
The new Cycle 25, peaking around the middle of the decade, appears likely to be more active. “If you look at the beginning of this year, things are very crazy. We’ve had a solar flare almost every week,” she said. The current cycle is trending higher than predictions, increasing the chances for more, and more powerful, solar storms over the next several years. “We’re already way beyond where we predicted at this point.”
Solar storms can also disrupt satellite operations or even damage components. This could affect smallsats in particular, which have often used commercial-off-the-shelf (COTS) electronics that are more susceptible to solar activity than radiation-hardened components that are more expensive and can take longer to order.
Industry officials at the conference said they have not yet noticed any major shifts by companies and organizations from COTS to rad-hardened electronics for smallsats prompted by concerns about increased solar activity. One option for satellite operators, they said, is to use rad-hardened components on critical subsystems and retain COTS components on other systems that can handle occasional disruptions.
Fang said satellite operators cannot ignore the effects of solar storms. “It’s very important that we all be aware of the impact of the space environment, how your satellite is going to mitigate this radiation environment and how you’re going to mitigate the drag effects.”