15 Phenomena Science Still Has No Answer For

12. The Flyby Anomaly

During gravity-assist maneuvers, some spacecraft have experienced tiny, unexplained changes in velocity—a puzzle known as the flyby anomaly. Despite rigorous calculations and repeated observations across several missions, no definitive explanation has emerged. This subtle boost remains at odds with established physics, prompting speculation about overlooked forces or even new physics. For more information, see JPL.