Man-made space weather

Major geomagnetic storms produce dramatic gradients in the ionosphere's total electron content (TEC) that cause errors in GPS-dependent navigation systems, such as those used by the U. S. Coast Guard and the Federal Aviation Administration. Here we describe the first use of GPS signals to detect large-scale gradients in TEC very similar to those found during ionospheric storms but produced instead by the exhaust gases of a large Titan rocket launched from the Kennedy Space Center. The severe ionospheric perturbations of 30 April 2005, observed simultaneously by optical emission from the thermosphere and by GPS diagnostics of the ionosphere, describe a unique type of space weather effect caused by nonnatural sources.