The fuel component in many
hypergolic engines used in the Apollo
program, especially the descent and ascent engines in the lunar
module. It is composed of hydrazine and
unsymmetrical dimethylhydrazine in approximately 50-50 proportions by
weight. The associated oxidizer is nitrogen tetroxide.
In the narrow sense, a hypergolic rocket fuel used with nitrogen
tetroxide. It has the chemical formula N2H4 and
is highly toxic and corrosive. In the broader sense it refers to a
number of chemically related hypergolic fuels including monomethyl
hydrazine and unsymmetric dimethylhydrazine.