The Venusian clouds have been studied extensively by space missions, most recently by the European Space Agency's Venus Express mission. These studies have shown that the Venusian clouds are composed primarily of sulfuric acid droplets and that the temperature and pressure conditions within the clouds are extremely harsh. The temperature at the cloud tops is about -45 degrees Celsius, and the pressure is about 90 times that of Earth's atmosphere. These conditions are too extreme for any known life form to survive.