Alexei Leonov, a Soviet-era cosmonaut who was the first human to conduct a spacewalk in 1965, died Friday in Moscow aged 85, his assistant said. "He died today in Moscow at the Burdenko hospital after a long illness," Natalia Filimonova told AFP. The Russian space agency Roscosmos said it was saddened to announce the death of "cosmonaut No 11" who was twice decorated with the country's top honor, the Hero of the Soviet Union.