Stormy Weather

Even passengers in high-flying jets, like the Concorde, which carries a radiation detector, might receive several chest X rays' worth of radiation in a solar storm. During the last maximum, says Ernie Hildner, director of NOAA's Space Environment Center, "the Concorde's alarm went yellow five times. It never went red." That would have required the pilots to dive immediately to lower altitudes, seeking protection in the thicker atmosphere.

In some ways, the earth is better prepared than it was 11 years ago. One telescope aboard SOHO can provide three or four days' warning of major solar events by spotting coronal mass ejections. Other instruments--an extreme ultraviolet telescope aboard SOHO and an X-ray telescope on Japan's yohkoh spacecraft--are looking for developing flares that might similarly hurl their fury at the earth.

Still, only ACE, sampling every earth-bound emanation, can flash a red alert, providing up to an hour's notice of a solar strike. Aware that space weather forecasting is in its infancy, NASA this week will propose a $500 million Living with a Star program. If Congress approves, the agency will launch more than 50 early-warning spacecraft by the next solar maximum, due in 2011. Flying fantastic solar sails, some would circle the sun. Others would monitor the terrestrial magnetic field. Still others would stand as sentinels in high earth orbit to spot dangerous intruders from our star.