Fueled partly by the Cold War, the 1960s became the decade of rapid development of rocket technology particularly in the Soviet Union (Vostok, Soyuz, Proton) and in the United States (e.g. the X-15[81] and X-20 Dyna-Soar[82] aircraft). There was also significant research in other countries, such as France, Britain, Japan, Australia, etc., and a growing use of rockets for Space exploration, with pictures returned from the far side of the Moon and unmanned flights for Mars exploration.