Launch of Venera 4

Venera 4 was a Soviet space probe that became the first to transmit data from within the atmosphere of another planet. It consisted of a bus and a descent capsule, and the capsule was released as the spacecraft approached Venus and parachuted down through the atmosphere, sending measurements of temperature, pressure and composition. The data showed that the atmosphere was made up mostly of carbon dioxide, and that conditions were far harsher than expected, with much greater pressure. The capsule stopped transmitting while still high above the surface, apparently crushed by the pressure, though Soviet scientists at first thought that it had reached the ground. The probe's data, compared with those of the American Mariner 5, led to a better picture of Venus.

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