Nature has a quite long piece (and quite sensational headline) on the way Earth’s “evil twin,” Venus, is inspiring a new generation of interplanetary explorers to go back to find out what went wrong:
Garvin, the chief scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, is the principal investigator on a proposed mission to Venus that would drop a probe through its atmosphere. That’s why he hired two pilots in August 2016 to plunge a helicopter towards the ground while he tested what a Venus probe might be able to photograph. The harrowing ride was worth it: researchers would love to get their hands on pictures of Venus with so much detail that the scenery would become familiar. “These images would be like you landing in your backyard,” he says.
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The Indian Space Research Organisation (ISRO) will be first to lift off when it launches an orbiter to Venus in 2023. The United States could follow close behind. Garvin and his colleagues are one of a handful of groups that will soon propose missions to NASA that, if selected, would take off in 2025. The European Space Agency (ESA) is currently considering a proposal to send an orbiter to Venus in 2032. And the Russian space agency Roscosmos is working in collaboration with the United States to send a daring mission to the planet any time from 2026 to 2033, which would include an orbiter, a lander that would send back short-term readings and a research station that would survive for much longer.
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But momentum is building to explore Venus, in part because scientists say it could hold the secret to understanding what makes a planet habitable. Once Earth’s twin, today Venus is a hellish abode where surface temperatures reach more than 400 °C, atmospheric pressures slam down with enough force to crush heavy machinery and clouds of sulfuric acid blow through the sky. If researchers could decipher why conditions on Venus turned so deadly, that would help them to assess whether life might exist on some of the thousand-plus rocky worlds that astronomers are discovering throughout the Galaxy.
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Recent research has even suggested that it might have looked like Earth for three billion years, with vast oceans that could have been friendly to life. “That’s what sets my imagination on fire,” says Darby Dyar, a planetary scientist at Mount Holyoke College in South Hadley, Massachusetts. “If that’s the case, there was plenty of time for evolution to kick into action.”
That could mean that Venus was (somewhat surprisingly) the first habitable planet in the Solar System — a place where life was just as likely to arise as it was on Earth. That alone is a reason to return to the former ocean world. “Why are we investing so much time looking for life on Mars when it only had liquid water for 400 million years?” Dyar asks. “And then there’s Venus with three billion years of water and no one loves her.”
Yet there’s no question that something went terribly wrong. Although Earth and Venus began in a similar fashion, the two have wandered down drastically different evolutionary paths — diverging perhaps as recently as 715 million years ago.