It occurs to me that I've never seen an explanation for this, and I'm curious if anyone here has any ideas or information. On the bottom of the Galaxy-class's warp nacelles (and related ships like the Nebula and New Orleans and so on), there's a graphic between the pylon and the yellow grill behind the bussard collector. It looks sort of like a hand phaser or emitter of some sort, with a bubble in front of it. Here's a close-up of it on the studio model. Does anyone know what the deal is with this icon? The best I can think of is that the bubble represents hydrogen and the graphic is a sort of "this end towards interstellar gas" sign for the ramscoop, but that doesn't quite add up.