In the early 1960s, scientists developed the gravity-assist method, where a spacecraft would conduct a flyby of a major body in order to increase its speed. Many notable missions have used this technique, including the Pioneer, Voyager, Galileo, Cassini, and New Horizons missions. In the course of many of these flybys, scientists have noted an anomaly where the increase in the spacecraft’s speed did not accord with orbital models. This has come to be known as the “flyby anomaly”, which has endured despite decades of study and resisted all previous attempts at explanation. To address this, a team of researchers...