The space shuttle Endeavor, which made its final space voyage in September of 2012, used primarily hydrogen, oxygen, hydrazine (N₂H₄), monomethylhydrazine (CN₂H₆), and nitrogen tetroxide (N₂O₄) as fuels. As it took off for a space voyage, the spacecraft would carry 835,958 gallons of these fuels with a total weight of roughly 1.6 million pounds!