Spacecraft headed to harmless asteroid slammed by NASA in previous save-the-Earth test
CAPE CANAVERAL, Fla. — A spacecraft blasted off Monday to investigate the scene of a cosmic crash. The European Space Agency's Hera spacecraft rocketed away on a two-year journey to the small, harmless asteroid rammed by NASA two years ago in a dress rehearsal for the day a killer space rock threatens Earth. Launched by SpaceX from Cape Canaveral, it's the second part of a planetary defense test that could one day help save the planet. The 2022 crash by NASA's Dart spacecraft shortened Dimorphos' orbit around its bigger companion, demonstrating that if a dangerous rock was headed our way, there's a chance it could be knocked off course with enough advance notice. Scientists are eager to examine the impact's aftermath up close to know exactly how effective Dart was and…