SpaceX’s new rocket motor (for propulsive landings, just like the ones in the scifi stories) has “shock diamonds” in its plume. The phenom was first seen in the 1950s in the exhaust plume of the Bell X-1, the first craft to fly faster than the speed of sound. The “diamonds” are more visible in this video of the motor’s recent test firing (below) in McGregor, Texas, just up the road from the rancho.
THE TEXAS SCRIBBLER 