The interstellar comet 3I/ATLAS is approaching the Sun and boosting its tail. Meanwhile, Europa Clipper is positioned such that between October 30 and November 6, 2025, it could intercept ions from the comet’s ion-tail. This alignment happens because solar wind carries charged particles from the comet outward, and a computer model named “Tailcatcher” shows Europa Clipper may lie in their path.

BulletsIn

• The comet is interstellar (origin outside our Solar System) and is undergoing increased activity as it nears perihelion.

• The ion tail is a stream of charged particles pushed away from the Sun by solar wind — separate from the dust tail

• Researchers Samuel R. Grant and Geraint H. Jones used Tailcatcher to estimate the window when Europa Clipper may encounter the tail.

• Europa Clipper has the necessary instruments (plasma and magnetometer sensors) to detect ions and magnetic distortions

• The chance depends on solar wind direction and strength, and on the comet’s activity level.A companion spacecraft, Hera (ESA), might also cross the tail between October 25 and November 1, but it lacks the charged-particle instruments

• If successful, this could be the first in-situ measurement of an interstellar object’s tail by a spacecraftEven if Europa Clipper misses, the model and opportunity show how spacecraft can exploit serendipitous alignments for high-value science