Grinpoon hopes that by then, the unanswered scientific questions will be impossible to ignore. He wants to know why Earth's global climate models break down on Venus, which has an atmosphere composed of 97 percent carbon dioxide—and what that reveals about the hidden fine-tunings of Earth models.
Similarly, Gordon Chin, a project scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, proposed a mission that would explain why the same chemical processes that destroy ozone in Earth's atmosphere stabilize carbon dioxide in Venus's. And Suzanne Smrekar, VEXAG co-chair and a scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif., wants to follow up on a 2010 finding in which she and her colleagues used Venus Express data to identify hot spots on the planet's surface—evidence for volcanism within the past few million years. A clearer picture of volcanism on Venus and its history could help to explain how the planet's runaway greenhouse effect got going. "We need another laboratory to test what we think we know on Earth," says Chin.
This article is reproduced with permission from the magazine Nature. The article was first published on September 2, 2011.