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NASA Prepares to Return to Venus for the First Time in Decades

Venus is back on the menu for space exploration! NASA announced the selection of not one, but two new missions to Earth’s closest planetary neighbor. 

The first mission — Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging, or just DAVINCI+ — will investigate Venus’s atmosphere, and launch a probe into its thick, hot, acidic clouds to measure their composition and conditions directly. DAVINCI+ will also capture the highest resolution images ever taken of Venus’s surface, including an unusual feature called “tesserae.” Some scientists believe these “tesserae” might be a Venusian version of Earth’s continents, minus the bordering oceans that define them. 

Composite image of Venus taken by JAXA’s Akatsuki spacecraft. (JAXA/ISAS/DARTS/Damia Bouic)

The second mission — Venus Emissivity, Radio Science, inSAR, Topography, and Spectroscopy, or VERITAS — will examine Venus’s surface, using radar to penetrate the planet’s thick clouds and create a detailed global geologic map. VERITAS will search for active volcanoes, and investigate a long-standing mystery. Venus appears to have suffered a global cataclysmic event that completely reshaped its surface in the past, but we don’t yet know why or what happened. 

Both missions are expected to launch sometime around 2028 to 2030. 

A Long Awaited Return

The last mission NASA sent to Venus was Magellan, over 30 years ago. Since that time, only spacecraft bound for other destinations, such as the Mercury explorer MESSENGER and the solar deep-dive Parker Solar Probe, have swung briefly by Venus, using the planet’s gravity to steer their course. 

Digital model of a volcano on Venus’s surface created from radar measurements made by NASA’s Magellan spacecraft. (NASA)

The intensely hot, high-pressure environment on Venus is one reason for the dearth of active exploration there.  Also, researchers believed that it is not a world where they could hope to find life  — unlike Mars, where the missions Curiosity and Perseverance are intensely examining that possibility.  

Venus is a very different planet than Earth, and its harsh environment makes exploring its surface a huge technological challenge. Global surface temperatures hold constant around 470 degrees Celsius, hot enough to melt lead, and its atmospheric pressure is equal to the water pressure a kilometer deep under Earth’s oceans. The few spacecraft that have ever landed there did not last long before succumbing to the hellish conditions.

Image taken from the surface of Venus by the USSR’s Venera 13 spacecraft. This is one of the few images ever taken from Venus’s surface. (Roscosmos)

Is Venus Earth’s ‘Evil Twin’?

But there are striking similarities between Venus and Earth. Venus is almost the same size as Earth, unlike Mars, which has received so much attention from NASA and other space agencies over the decades even though it’s about half the size of Earth.  And though Venus is closer to the sun, the extreme temperature of its atmosphere can be attributed in large part to a dominance of carbon dioxide, a greenhouse gas that traps solar energy in the form of heat. 

Observations of Venus’s atmospheric chemistry have fueled a hypothesis that the hell-world of today may have once been more temperate, with a cooler atmosphere, oceans of water, and possibly life-friendly conditions. What happened to change Venus’s environment so profoundly is a question NASA hopes its two new missions will help answer. 

Was There Ever Life on Venus?  Does Life Exist There Now?

The detection of the molecule phosphine high in Venus’s atmosphere by a team of researchers in the United Kingdom has raised new questions about the possibility of life on what was once thought to be an inhospitable world. 

Phosphine is a chemical found on Earth in association with certain biological processes, such as some anaerobic microbes (ones that do not need oxygen to live), the decomposition of organic matter, as well as human industrial activity, so its presence on Venus is an eye-opening surprise. 

Infrared image of the night side of Venus, captured by JAXA’s Akatsuki spacecraft. (JAXA/ISAS/DARTS/Damia Bouic)

Given Venus’s crushing surface pressure and roasting temperature, it’s hard to imagine any form of life existing there, but conditions at higher altitudes are more forgiving. At heights of 30 to 40 miles above Venus’s surface, the pressure and temperature in the atmosphere are similar to those on Earth’s surface. 

If oceans once existed on Venus, they likely evaporated as temperatures soared. But what happened to turn up the heat? 

Was there life on Earth’s closest sibling-planet? What was it like? Could life of some form still thrive there today, high up in the atmosphere, a safe distance away from Venus’s punishing surface?

Venus holds many tantalizing mysteries, and NASA is doubling down on solving them.

Copyright 2021 KQED