During the rollout of the Apollo 10 Saturn V, three service arms extend to the vehicle from the Launch Umbilical Tower (LUT). The S-II intermediate arm at top provided fueling and was retracted at launch; the S-II aft arm (center), which provided access, and the S-IC forward arm (below, providing pneumatic, electrical, and air-conditioning interfaces) were both retracted before launch. Two of the eight ullage motors are visible on the Saturn’s interstage, to the left of the center arm. These motors fired to briefly nudge the stage forward, to settle its fuel prior to ignition of its five J-2 main engines. The two fairings to the right of the service tunnel above the interstage housed liquid hydrogen feed lines.