Gemini 6A also aborted after engine ignition. The astronauts climbed out, the engineers found the problem, and they launched successfully three days later. Li

Gemini 6A also aborted after engine ignition. The astronauts climbed out, the engineers found the problem, and they launched successfully three days later. Liquid-fueled engines are inherently restartable. Otherwise, you wouldn't be able to test an engine without throwing it away afterwards. Sometimes manual intervention is required, though. For example, the starter cartridge on the Titan was a consumable part, and had to be replaced before restarting the engine.