Bussard collectors are the glowing intakes at the front of a starship's warp nacelles that gather interstellar hydrogen for use as fuel.
Named for the ramscoop concept proposed by physicist Robert Bussard, the collectors use magnetic fields to draw in hydrogen from the thin gas of interstellar space. The collected material can supplement a ship's fuel stores during long missions. They form part of the nacelle assembly that also houses the warp coils.
On most Starfleet designs the collectors sit at the forward tip of each nacelle, where their red or orange glow became a signature of Federation starships from the original Enterprise onward.