Same reason the US flag was 'flapping' in the 'wind' on the Moon. ;) Without any air, there's nothing to stop the head from travelling without running into con

Same reason the US flag was 'flapping' in the 'wind' on the Moon. ;) Without any air, there's nothing to stop the head from travelling without running into control issues. The gas molecules actually act as a buffer preventing too much movement. The head will flap about with the slightest motion like a flag in a vacuum.