Mariner 4 launch. Atlas-Agena D rocket lifts off carrying Mariner 4, the first spacecraft to produce close-range images of the planet Mars. Mariner 4 was launched on 28 November 1964. After 228 days and 523 million kilometres (km) it passed Mars at a distance of 9844 km on 14 July 1965. Twenty-one full images, covering about 1% of the surface of Mars, showing that it was heavily- cratered and very dry. Mariner 4 also discovered that Mars had no radiation belts or magnetic field, indicating that the planet did not have a metallic core. It also found that the carbon dioxide atmosphere was very thin. The Atlas-Agena D rocket was a development of a military missile.