Until the issues of cooperation have been imposed, overcoming the distance between Mars and Earth has been the goal of the individual efforts of the United States and the Soviet Union. The adventure itself began in 1960 with the Soviets sending spacecraft, called Mars Probe, but the first to enter the orbit of Mars was the Mariner 4 of the United States. Since then several attempts have been made to reach Mars, many incorrect, and some of them have gone well. The highlights are: