NASA’s DART asteroid redirection mission may have inadvertently made future asteroid deflections much more challenging after its test sent boulders hurtling through space on unexpected trajectories. In September 2022, the DART mission successfully altered the orbit of asteroid moon Dimorphos. Unfortunately, the smaller space rocks that were dislodged when the kinetic impactor struck the natural satellite achieved three times the momentum of the spacecraft that created them. The University of Maryland-led team (UMD) behind the new research paper on DART’s repercussions cautions that results demonstrate planetary defense may be considerably more complex than previously suspected, with the potential for many...