Derived from the older V2 rocket engine, the Redstone A-6 and A-7 represents America’s first large scale rocket engine. With a thrust of 78,000 pounds, the engine was capable of sending an astronaut to sub-orbital space. While the engine’s fuel was initially a combination of liquid oxygen and ethyl-alcohol, the ethyl-alcohol was replaced by hydyne, a highly reactive and toxic fuel. However, hydyne increased thrust to a maximum of 83,000 pounds. This increase was just enough to send America’s first satellite, Explorer I, into orbit.