Marsnik 1 and 2, also known as Mars 1960 A/B and Korabl 4/5, were two failed Soviet Mars probes launched on 10 and 14 October 1960. They were the first attempted interplanetary spacecraft and similar in design to Venera 1 with an on-orbit mass of 650 kilograms. Marsnik 1 and 2 were intended to investigate interplanetary space between Earth and Mars, study Mars and return surface images from flyby trajectories, and study the effects of extended spaceflight on onboard instruments. Both probes were lost during launch when their third stages failed to ignite. At the time, Soviet premier Khruschev was on a visit to the United States. Furious at the failures, he insisted that a third probe be hurriedly ready to dispatch before the 1960 launch window closed. On 23 October 1960, the rocket failed to liftoff on time and the Soviet commander, Marshall Nedelin, demanded that the vehicle be examined at once. Ignoring normal safety precautions the technicians approached the fully-fuelled rocket which suddenly exploded, killing Nedelin and almost the entire launch team. Although denied for years, the story eventually leaked to the West and became known as 'The Nedelin Catastrophe.'