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ARI SHAPIRO, HOST:
Right now, three missions from Earth are headed to the planet Mars. But some planetary scientists say it’s time to look at another of Earth’s neighbors: Venus. NPR’s Geoff Brumfiel has more on why Venus is getting attention.
GEOFF BRUMFIEL, BYLINE: Venus is actually the first planet where humans have ever landed a probe.
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UNIDENTIFIED PERSON: (We speak a language other than English).
BRUMFIEL: Fifty years ago, the Soviet Union sent its Venera 7 lander through the clouds of Venus.
MARTHA GILMORE: Venus’s atmosphere is so dense, it’s almost like you can float. It is thick enough that you can just gently land on the surface.
BRUMFIEL: Martha Gilmore is a planetary scientist at Wesleyan University who studies Venus. The landing was smooth. But after that it became difficult. The spacecraft faced pressures like those deep under the ocean, temperatures of around 900 Fahrenheit. It only lasted about an hour and a half.
GILMORE: Before undergoing what we call thermal death.
BRUMFIEL: This is the science that speaks for saying it fried on the hard surface of Venus. But the data it sent back, combined with data from other orbiting landers and satellites that went to Venus over the next several decades, taught us a lot about the planet. And scientists now believe that a few billion years ago, Venus would have been very different.
SARA SEAGER: Venus started, we all believe, as a pleasant place …
BRUMFIEL: Sara Seager is at MIT.
SEAGER: … With good surface temperatures, with an ocean of liquid water like the Earth still has today. Maybe it had blue skies and clouds of water. And then something went terribly wrong with Venus.
BRUMFIEL: The best guess is that the carbon dioxide from the volcanoes on the surface triggered a runaway greenhouse effect. This, combined with Venus’ proximity to the sun, made it warmer. The oceans evaporated and warmed even more to become the hot and hostile Venus we see today. Sue Smrekar is a senior researcher at NASA’s Jet Propulsion Laboratory. She currently helps conduct a small mission to the surface of Mars, but she would also like to return to Venus.
SUE SMREKAR: Sometimes, people ask me: I am blown away because I feel there are so many reasons to go to Venus.
BRUMFIEL: Volcanoes, geology. But for Smrekar, it really depends on the similarity of Venus to the Earth.
SMREKAR: How did these two planets that are so similar in size, distance from the sun and probably very similar at the beginning of their evolution – how did they become so different?
BRUMFIEL: And Martha Gilmore says the biggest question of all is: Could life have started on Venus as it did on Earth?
GILMORE: I mean, that’s the question we have about all the solar system worlds we explore. Was it habitable? And then what follows is: was it inhabited?
BRUMFIEL: With the revelations about ancient oceans, the answer to this first question is to lean towards yes. And just recently, there was a discovery that suggests that life could be living on Venus today. Sara Seager and collaborators found evidence of a chemical called phosphine in the atmosphere, something that could be explained by the microbes living in the clouds of Venus. Seager says the phosphine signal is still tentative and needs to be followed up. But Gilmore says that regardless of the result, the research has focused people’s attention on Venus.
GILMORE: I’m happy that we’ve all thought about Venus and this possibility. This is how science is supposed to work. So let’s go to Venus. Here we go.
BRUMFIEL: There are now several proposed missions to go to Venus; however, some of these missions compete with trips to other fantastic destinations: the moons of Jupiter and Neptune. NASA could make a final decision early next year.
Geoff Brumfiel, NPR News.
(SOUNDBITE OF YEAH YEAH YEAHS SONG, “DRAGON QUEEN”) Transcript provided by NPR, Copyright NPR.
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