Future Tense

Why NASA Is Setting Its Sights on Venus Again After Decades

A man stands onstage with his back to a lectern and looks at a large screen that says "DAVINCI+ and VERITAS."
NASA Administrator Bill Nelson announces two new planetary science missions to Venus for the late 2020s called VERITAS and DAVINCI+. Bill Ingalls/NASA/Getty Images

Elon Musk’s gaudy Tesla tribute to the stars and his company’s proposed Doge-1 mission may be at the center of space exploration’s meme orbit, but Venus is quickly becoming a new center of space exploration’s scientific efforts. Two new projects—that promise to do a lot more than shoot a Roadster into space—are on NASA’s horizon.

On June 2, NASA Administrator Bill Nelson announced the next two mission selections for the space agency’s Discovery Program, which uses relatively small (compared with, say, broader New Horizons or flagship programs) missions to “unlock the mysteries of our solar system.” The selection process for this round started in 2019, when NASA put out a Discovery Announcement of Opportunity that solicited mission ideas for a new round of Discovery Program funding. The four highly competitive finalists announced in February 2020 included two missions planned for the solar system’s hottest planet, Venus; one for Neptune’s icy moon Triton; and one to the volcanic Jovian moon Io. Of the four finalists, a maximum of two were to receive funding. And both, it turned out, would be to Venus.

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The two chosen missions are DAVINCI+ (a mission to understand the atmospheric evolution of Venus) and VERITAS (a mission to better map the Venusian surface and subsurface), now both aiming for launch between 2028 and 2030. Together, they’ll be the first NASA spacecraft sent to the second planet in our solar system in nearly 40 years.

If Earth had a sibling, its name would be Venus. Sure, Mars has similar day lengths and axis tilt to Earth. And yes, all three planets dwell in our solar system’s habitable zone—with liquid water existing on their surfaces at one point. But in many key ways Earth and Venus are more strikingly similar: They have nearly the same size, gravity, density, mass, and chemical makeup. Mars is much smaller, less dense, and farther away on average than our Venusian family member. So while Venus receives about double the energy from the sun that Earth does, the two planets likely started out quite alike. Siblings, despite their common origin and upbringing, eventually take different paths in life; Venus and Earth are no exception. While Earth became home to all of the life thus far discovered in our universe, Venus became a toxic greenhouse—with an atmosphere of roughly 97 percent carbon dioxide and surface temperatures exceeding 850 degrees Fahrenheit.

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Historically, NASA largely ignored Venus to focus on Mars and other exploration objectives. The conditions on the surface are absolutely abysmal for explorers, electronic and human alike, so many scientists were wary of exploring what they believed to be a wholly dead planet. At most, a Venera lander lasted less than two hours on the surface. Unlike with Mars, where multiple rovers have survived for years, our face time with the Venusian surface has been extremely limited. Even the new NASA probe DAVINCI+ is expected to last only 20 minutes on the surface after completing two flyby passes to image Venusian clouds.

There have been American flybys and probes sent to the planet, but the Soviet Union is still the only nation to intentionally (and controllably) land spacecraft on the surface of the planet. (I guess the U.S. lost the Venus front of the Cold War.) Most atmospheric information and surface data from Venus were collected by the Soviet Union.

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Beginning in 1961, the Soviet space program sent dozens of spacecraft to the planet on flyby, probe, and lander missions. Its Venus program achieved some of the greatest successes of human space exploration—including the first landing of spacecraft on another planet and the first photos from another world’s surface.

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A second wave of Venus missions kicked off with the European Space Agency’s 2005 Venus Express, whose findings suggested that the planet might be geologically active. The Japan Aerospace Exploration Agency’s Akatsuki orbiter launched in 2010 and is currently in orbit around Venus; the objective is to clarify the motion of the Venusian atmosphere and establish a planetary meteorology. The Indian Space Research Organisation is planning to send an orbiter called Shukrayaan to Venus in 2024 to map surface and subsurface features, along with studying the atmosphere’s interaction with solar wind. Roscosmos, the Russian space organization, is planning a collaborative effort with European Space Agency scientists to launch an orbiter-lander combo—the Venera-D—to study water content and seismic activity among other objectives in 2029. Venus is seeing a scientific renaissance.

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Understanding how the climate, surface, and interior of Venus evolved is valuable given the similarities between Earth and Venus. The mechanics that led Venus to heat up could help scientists here on Earth better understand our own climate’s change—acting as a test case of what happens when a runaway greenhouse effect takes charge. Furthermore, research into the past existence of surface water and atmospheric conditions has come into vogue. Interest in Venus has also been buoyed by (generally debunked) findings in 2020 that phosphine (a biomarker) may be present in the atmosphere. While likely untrue, the discussion that ensued helped to build the profile of the planet as a spot for exploration (although, as Lucianne Walkowicz has previously explained for Future Tense, the possibility of life on the planet could further complicate Venusian exploration). As our knowledge of Venus has developed, more and more scientists are beginning to think that the planet might not be as dead and dry as many thought it to be—or at least that it wasn’t at some point in its past.

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Studying Venus also gives scientists an opportunity to study the effects of sulfur dioxide in the atmosphere—which is valuable given past proposals to inject sulfur droplets into the atmosphere to mitigate climate change here on Earth. Venus further provides scientists a way to test their ability to understand the chemistry of even more distant celestial bodies. As Stephen Kane of the DAVINCI+ mission explained to the American Chemical Society, “We’re never going to send a probe to Proxima Centauri b,” the closest exoplanet to Earth. What he means is that if we can’t model our planetary neighbor, we have no chance at modeling planets in stellar systems light-years from our own. Finally, Venus helps us better understand why our planet has developed plate tectonics (a key player in modulating carbon dioxide and recycling material on Earth), and the other rocky planets in our solar system have not.

At a more existential level, exploring Venus also allows us to determine whether microbial alien life exists (or existed) on the planet—phosphine or no phosphine. The new NASA missions will assist in that goal, with DAVINCI+ attempting to study climate change on the planet to determine past habitability and VERITAS analyzing the surface composition of Venus for comparisons with Earth. I believe most of us, as humans, have an innate desire to determine if we truly are alone in our universe. And if, like me, you are a space nerd, well, then exploring Venus is just plain cool.

Future Tense is a partnership of Slate, New America, and Arizona State University that examines emerging technologies, public policy, and society.

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