Russia has been using variants of Proton rockets in its space program since 1965, and the design is showing its age. For starters, every launch is an environmental mess -- Proton uses toxic chemicals where newer rockets have moved on to cleaner fuels. The country will have to put up with ancient technology for a while longer, however. Rostec Corporation council chairman Yuri Koptev has warned that Angara, Proton's long-delayed successor, isn't expected to replace the older rocket before 2024. Koptev didn't explain why it would take so long, but he was confident the high costs of Angara would come down through refinements.