SpaceX has been using its prototype “Grasshopper” rocket to develop technology needed to re-fly Falcon boosters back to their launch sites so the motors can be refurbished and reused.

But Grasshopper’s last liftoff apparently caught some onlookers by surprise.

PHOTOS: SpaceX Grasshopper Rocket Takes Giant Leap

In a video posted on YouTube, a herd of cows reckons with the weirdness of a rocket blasting off its McGregor, Texas, pasture with a very basic instinct: Run!

“No cows were harmed in the filming of this,” quipped Adam Harris, SpaceX vice president of government sales, who showed the film at the American Institute of Aeronautics and Astronautics’ Space 2013 conference in San Diego this week.

Credit: SpaceX