science · 05 February 1974 · 50 years ago
In 1974, the U.S. space probe Mariner 10 returned the first close-up photos of the cloud structure of Venus, at a closest range of 5768-km. It also was the first time a spacecraft used a gravity assist from one planet to help it reach another planet, helping Mariner 10 reach Mercury in Mar 1974. Carbon dioxide and sulphuric acid make up the Venusian atmosphere and clouds, having a greenhouse effect that heats the surface to 485ºC, while obscuring any view of the planet's surface, where the atmospheric pressure is 90 times greater than at sea level on Earth. The Soviet probe Venera 9 which penetrated the clouds and landed on 22 Oct 1975, was briefly able to transmit images of the surface.
OnThisDay.net