MISSIONWhy explore Venus?

Figure comparing Venus and the Earth

Exploration of Venus helps us better understand our own planet.

Both the Earth and Venus are believed to have been born about 4.6 billion years ago. At the time, there may have been oceans on Venus like that found on the Earth. However, Venus today has no oceans and is covered by dense atmosphere composed of carbon dioxide. Venus is closer to the Sun than the Earth, so the temperature is higher and more water molecules evaporate into the atmosphere. This perhaps meant that the water vapor transmitted into the upper atmosphere was then broken down into hydrogen and oxygen by the ultraviolet rays from the Sun, with the lighter hydrogen atoms escaping into outer space. Without oceans, Venus is unable to dissolve carbon dioxide into the water like the Earth does, so this is how it may have accumulated vast quantities of carbon dioxide in the atmosphere.

Unlike on the Earth, the upper atmosphere on Venus rotates at a speed 60x faster than the surface. Earth-based meteorology is unable to explain why the atmosphere on Venus circulates in this way.

We are lacking concrete evidence to elucidate the reason why Venus is differ from the Earth. If we can determine how the environment on Venus has been made, we should be able to understand why the Earth became a planet with warmth and humidity capable of supporting a diversity of life. Besides, if we could achieve a system of Venusian meteorology explaining the circulations of its atmosphere, we could pair this with our existing knowledge of terrestrial meteorology to develop a universal planetary meteorology. Considering meteorological phenomena on the Earth from the view point of planetary meteorology allows us to more deeply understand why the atmosphere on the Earth is the way it is and how it may change in the future.