Solar storms ahead: Is Earth prepared?
Sunspot cycle beginning in 2012 may put satellites, power grids at risk.
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CMEs also can cause the Earth’s atmosphere to expand temporarily. This can cause low-orbit satellites, such as the constellation of Global Positioning System markers used for navigation, to drag in the denser air. Combined with changes in the transmission of radio waves caused by CMEs, this can lead to errors in positioning. The magnetic field also can induce glitches or even damage satellites.Skip to next paragraph
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Ron Mahmot, who manages the Satellite Operations Control Center for the National Oceanographic and Atmospheric Administration (NOAA), isn’t particularly concerned about potential damage from solar activity. NOAA has had only one satellite damaged by a solar flare. The 1994 incident merely shortened the life of the orbital weather-watcher; it did not totally disable it. And for the most critical NOAA satellites, those that monitor the United States from geosynchronous orbit, there is an on-orbit spare in place, with another that was due to launch at the end of April, and yet another already in production.
For satellite TV provider DirecTV, “solar events are nonevents. In the more than 14 years that we’ve been operating satellites, we’ve never experienced a signal outage or interruption of any kind due to solar flares,” a spokesman writes in an e-mail. “The history of communications satellites is one of extraordinary reliability.” Each has shielding and a backup system.
Ms. Guhathakurta of NASA is less certain: “In the past, satellites were built with much greater integrity,” she says. “Now we’re putting up so many satellites, and the electronics are changing. I don’t believe the electronics are as well tested for radiation as in the past.”
Part of the problem, she says, is that we don’t know what the most powerful solar flare might look like. And even if 2012 brings a mild solar peak in terms of quantity, the power of the flares is not directly associated with their number.
“We cannot say anything about the kind of flares or coronal mass ejections we are going to see in a given cycle,” she says. The most powerful solar flare in modern times occurred during a solar lull in 2006.
This unpredictability makes protecting satellites tricky. Guhathakurta’s pair of STEREO spacecraft recently captured the first 3-D image of a CME burst, an important step toward understanding them.
As scientists gather more information, satellite companies have a few tricks to protect their space-bound electronics. It’s hard to determine the effectiveness of shielding – mostly because experts don’t fully know what the sun is capable of spewing out. Another satellite defense would be “safe modes,” where administrators turn off most of the on-board electronics to protect it from going haywire. This can save the satellite but would interrupt whatever services it offered. Safe modes also require some kind of early warning – technology that is nascent at best.