Is There Life on Venus?

The truth about Venus came as something of a shock. Well into the space age astronomers believed that the planet had a climate similar to the tropical regions of Earth. Many envisioned a jungle world swarming with exotic life. Others imagined deserts stretching across Venusian continents, or warm shallow seas filled with swamp creatures.

Venus; captured by NASA’s Mariner 10 mission in 1974. The surface of Venus is eternally hidden by a thick layer of clouds. Image credit: NASA/JPL-Caltech

It was an easy mistake to make. Venus is similar to Earth in size, and though it is closer to the Sun, astronomers realised that its thick atmosphere should reflect much of the heat back into space. If Venus was like Earth — which seemed reasonable — then it could be filled with oceans, with deep clouds of water surrounding the planet. Venus, scientists and writers thought, was torrid but inhabitable.

The first hints that this view was wrong come in the early 1960s. Radio measurements of the planet revealed soaring temperatures — reaching hundreds of degrees Celsius. Even so, the old ideas were hard to abandon. When the Soviets built two probes to visit Venus in 1964, they designed them to float — just in case they landed in an ocean.

Those spacecraft, like many of the early interplanetary missions, failed to reach Venus. But when the Soviets did, finally, send a probe through the Venusian atmosphere, they found a world more awful that anyone had expected. None of the first five probes to Venus survived more than an…