Do you know which planet Carl Sagan wanted to terraform first? It might surprise you
In his first major scientific article, Carl Sagan focused on one planet, the hottest in the solar system. In addition to discussing its own greenhouse effect, he proposed terraforming it to make it habitable by humans. The interesting part? The planet wasn’t Mars.
Sagan was one of the first astronomers to hypothesize about the hot surface temperature of Venus. He believed a greenhouse effect was at play and that it could be used to terraform the planet (that may also be why Venus is hotter than Mercury, which is closer to the sun).
As Keay Davidson recalls in an excellent biography, Sagan proposed seeding Venus with microorganisms that would feed on water vapor in the atmosphere. They’d convert carbon dioxide to oxygen, like plants, and when they decomposed, they’d yield carbon and water to gradually create an oxygenated atmosphere. The brash proposal was the first article to gain Sagan mainstream attention.