Stormy Weather

摘要

A million miles from the earth, NASA's Advanced Composition Explorer (ACE) space-craft suddenly found itself under assault. Late in January, the tiny, instrument-packed spacecraft was buffeted by an exceptionally powerful burst of particles spewed out by the sun. In the space-environment control room at the National Oceanic and Atmospheric Administration (NOAA) headquarters in Boulder, Colo., alarms sounded. "All of a sudden, a blast wave of solar wind showed up at the ACE spacecraft," says NOAA's Joe Hirman, "as dense as any we've seen, and, bam, 30 minutes later the earth's magnetic field got hit hard."