ROBERT SIEGEL, host:
Airlines are paying extra attention these days to the weather in space. That's because thousands of commercial flights each year now take shortcuts over the North and South Poles. Those flights are vulnerable to cosmic storms caused by disturbances on the sun, events that can disable communication systems and even expose travelers to radiation.
NPR's Jon Hamilton looks at efforts to keep planes and people safe by predicting rough weather in space.
JON HAMILTON: On most days, United Airlines Flight 895 takes off from Chicago, flies over the North Pole and lands in Hong Kong without making a stop, but on four consecutive days in January 2005, the flight had to make a detour through Anchorage, Alaska. The reason: An eruption on the surface of the sun was sending a burst of electromagnetic radiation and charged particles toward Earth.
The Earth's magnetic field tends to funnel this energy to the North and South Poles. That's what causes the Northern Lights and similar auroras in extreme southern latitudes. The effect can be breathtaking from the ground, but Bill Murtagh from the U.S. government's Space Weather Prediction Center says you probably don't want to watch from an airplane crossing one of the poles.
Mr.�BILL MURTAGH (Space Weather Prediction Center): The air traffic controller could be talking to the pilot one minute and, really, literally within a minute or so, that signal can go from quite clear to scratchy noise and there's no longer any ability to communicate.
HAMILTON: Radio interference is just one problem. GPS navigation systems may stop working entirely. And in just a few hours, people onboard could be exposed to the amount of radiation in a dozen chest X-rays. Even so, Murtagh says, routes that cross the North and South Poles are increasingly popular. That's because they let planes take the shortest path between North America and Asia or Argentina and New Zealand.
Mr.�MURTAGH: So you're shaving off a couple of hours of flight time, which everyone appreciates - airlines, because it saves fuel and the customer because they're not on the plane as long.
HAMILTON: Which is why the number of polar flights has gone from just a handful a decade ago to more than 7,000 last year. Most of those flights have taken place during a relatively quiet period for space weather. Murtagh says that's because there hasn't been much activity on the sun during the past several years.
Mr.�MURTAGH: Right now in the solar minimum we're just turning the corner, and we'll continue to see an increase in solar activity over the next three, four, five years or so.
HAMILTON: As we reach what's called the solar maximum. All that has got the attention of the Federal Aviation Administration. Steven Albersheim from the FAA says the combination of more polar flights and more solar activity means air traffic controllers are increasingly likely to encounter a scenario they'd prefer to avoid.
Mr.�STEVEN ALBERSHEIM (Federal Aviation Administration): You've got aircraft, which are already en route, on their way over the high latitudes, and you have a solar event that was not foreseen.
HAMILTON: Albersheim says controllers have no choice but to begin diverting those flights. Then the real problems start.
Mr.�ALBERSHEIM: When you have a bad weather day, space weather, and an aircraft would have been dispatched, thinking that they can fly these high latitudes, then all of a sudden they get notification that there's got to be a diversion, air traffic control in Anchorage has to be able to accept all those flights.
HAMILTON: That scenario wouldn't happen if space weather forecasts were as accurate as their earthbound counterparts, but Bill Murtagh says they're not.
Mr.�MURTAGH: In the terrestrial weather in meteorology, we rely largely on models. And there are many different sets of models available to make forecasts, and these models are advanced and quite good. We are not there yet with the space weather models, although we are getting there.
HAMILTON: One promising model has emerged in just a past couple of weeks. It's being developed by researchers at the Space Weather Prediction Center, which is part of the National Oceanic and Atmospheric Administration. Alysha Reinard and her colleagues showed they could predict solar flares two or three days ahead of time. The trick was to track changes in the swirls of plasma beneath active areas on the surface of the sun.
Ms.�ALYSHA REINARD (National Oceanic and Atmospheric Administration): In Earth terms, it's most like a smoke ring.
HAMILTON: Reinard says the ring twists in a distinctive way before producing a flare.
Ms.�REINARD: We can pick up about 30, 35 percent to half, depending on how big the flares are. So we still miss a lot of them.
HAMILTON: But Reinard says even a model that's right only half the time could protect a lot of planes and the people on them from bad space weather.
Jon Hamilton, NPR News.