Hydyne is a mixture of 60% unsymmetrical dimethylhydrazine (UDMH) and 40% diethylenetriamine (DETA), developed in 1957 at Rocketdyne for use in liquid-fuel rockets.[1][2][3] Hydyne was used as the fuel for the first stage of the Juno I rocket that launched Explorer 1, the first successful satellite launch conducted by the United States. As part of Mixed Amine Fuel series of rocket fuels, it was designated as MAF-4.