A Nasa spacecraft rammed an asteroid at blistering speed on Monday in an unprecedented dress rehearsal for the day a killer rock menaces Earth.

The galactic grand slam occurred at a harmless asteroid 9.6 million kilometres away, with the spacecraft named Dart ploughing into the small space rock at 22,500 kmph. Scientists expected the impact to carve out a crater, hurl streams of rocks and dirt into space and, most importantly, alter the asteroid’s orbit.

Telescopes around the world and in space were aimed at the same point in the sky to capture the spectacle. Though the impact was obvious — Dart’s radio signal abruptly ceased — it will be days or even weeks to determine how much the Dimorphos asteroid’s path was changed.

The $325 million mission was the first attempt to shift the position of an asteroid in space. “No, this is not a movie plot,” Nasa administrator Bill Nelson tweeted. “We’ve all seen it on movies like Armageddon,’ but the real-life stakes are high,” he said.