Cometary Ions Trapped in a Coronal Mass Ejection

Ion tails of comets are known to extend radially away from the Sun over very large distances. Crossing these tails by spacecraft not specifically targeted to intercept them was believed to be extremely improbable, since that requires precise angular alignment of the spacecraft with a comet. We report here the fortuitous detection of cometary ions at large angular separation far from the comet. To explain this unexpected discovery, we conclude that these ions were ducted laterally along magnetic fields that were randomly distorted by a coronal mass ejection and that such transport increases the probability of an unplanned detection of comets.