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. It's the second part of a planetary defense test that could one day help save the planet.
SpaceX's Falcon rocket quickly disappeared with Hera into the late morning clouds. An hour later, applause erupted in the control center in Germany as the spacecraft separated from the rocket's upper stage and then called home. "It's an amazing day," the space agency's director general Josef Aschbacher said afterward.
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 what changes might be needed to safeguard Earth in the future.
