NASA returns to Venus to learn how it became a toxic, hot wasteland – and whether the planet has ever been habitable in the past

NASA is finally heading to Venus. On June 2, 2021, NASA Administrator Bill Nelson announced that the agency had selected two winners of its latest Discovery-class space mission competition, and both are heading to the second planet from the Sun.

I am a planetary scientist and avowed Venus evangelist, and this is why I am so excited for humanity to return to Venus.

This is the first time since the Magellan mission in 1989 that NASA has committed to sending spacecraft to study the shrouded planet next door. With the data that these two Venus missions – called VERITAS and DAVINCI + – will collect, planetologists can begin to tackle one of the solar system‘s greatest mysteries: why Venus, a planet almost the same size, density and age Earth, is it so much different from the world that humanity calls home?

Venus could once have been covered with oceans and clouds and could have supported life.
NASA / JPL-Caltech / Ames

An Earth gone wrong?

Venus is a rocky planet roughly the same size as Earth, but despite these similarities, it’s a brutal place. Although a little closer to the Sun than to the Earth, an uncontrollable greenhouse effect means it is extremely hot on the surface – around 870 F (465 C), about the temperature of a self-cleaning oven. The pressure at the surface is a crush 90 times the pressure at sea level on Earth. And to top it off, there are clouds of sulfuric acid covering the entire planet that corrode everything that crosses them.

But perhaps the most fascinating aspect of Venus is that she may have looked a lot like Earth before. Recent climate models suggest that in the past the planet may have had oceans of liquid water and a mild climate. It may have been habitable for 3 billion years before succumbing to some sort of climate catastrophe that caused the greenhouse to run wild. The purpose of these two new missions to Venus is to try to determine if Venus was really Earth’s twin, why it changed and if, in general, large rocky planets become habitable oases like Earth … or wasteland. burnt like Venus.

A square satellite with two long solar panels above a beige colored Venus.
The VERITAS mission will send a vessel carrying a powerful radar system into orbit above Venus.
NASA / JPL – Caltech

A fresh look at Venus

What may come as a surprise is that in the 1960s and 1970s, Venus was at the center of space exploration as Mars is today. The United States and the Soviet Union sent more than 30 spaceships in total to the second planet from the Sun. But since 1989, only two missions have been to Venus, and both have focused on studying the atmosphere – Venus Express from the European Space Agency and Akatsuki from Japan.

In contrast, the VERITAS and DAVINCI + missions will take a holistic view by exploring the geological and climatological history of Venus as a whole, in two very different but complementary ways.

The overall thick layer of sulfuric acid clouds covering Venus makes it almost impossible to see the surface with normal cameras. This is why the VERITAS orbiter – short for “Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy” – will carry a powerful radar system. This radar can look through the clouds and collect topographic imagery and data at up to 10 times the resolution of any previous mission to Venus. This will allow scientists to look for clues to Venus’ past climate that might be preserved in rock formations on the surface and could also determine whether the planet is geologically active today. And, finally, this exciting mission will use a special infrared camera to scan the atmosphere at very specific wavelengths in order to take the world’s first measurements of the rock composition of Venus – something scientists know very little about.

A circular probe with sampling equipment falling towards Venus.
The DAVINCI + probe will travel through the atmosphere of Venus collecting samples and taking photos before it finally collides with the Alpha Regio region.
NASA GSFC Visualization by CI Labs Michael Lentz and others

VERITAS ‘stable mate is DAVINCI +, or “Deep Atmosphere Venus Investigation of Noble gas, Chemistry and Imaging”. The DAVINCI + mission also involves an orbiter, but the real star of the show will be the meter-wide atmospheric probe. The spacecraft will fall into Venus’ atmosphere and free fall through thick clouds for about an hour before reaching the surface.

As it descends, it will take samples of the atmosphere, specifically measuring a variety of gases, including argon, krypton, and xenon. Different climate stories for Venus would lead to different ratios of these noble gases in the atmosphere – and so, by analyzing these ratios, scientists will be able to determine how much water the planet formed with, and even how much water it was. amount of water it has lost over the past 4.5 billion years.

But that’s not all the probe will do. Just before impacting the crash landing in an area called Alpha Regio which contains some of the oldest rocks on the planet, the probe will take infrared images of the surface as it appears through the darkness of the lower atmosphere. These images will be the first ever taken above the surface but below the cloudy bridge, showing planetologists Venus like never before.

An artist's impression of an exoplanet around a different star.
The study of Venus may offer valuable insight into how other potentially habitable rocky planets in the galaxy – like Kepler-186f, seen here in an artist’s rendition – might evolve.
NASA Ames / SETI Institute / JPL-Caltech

Now is the time to return to Venus

I’ve advocated for a return to Venus before, so to say I’m excited about these missions is an understatement. Venus may hold the key to understanding the past – and possibly the future – of Earth. As astronomers increasingly discover Earth-sized worlds around other stars, they need to understand if the outcome we see on Earth – blue skies, oceans, and even a thriving biosphere – is the norm. , or if the infernal and barren lands of Venus are the rule.

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Several decades of sustained exploration of Mars have shown that each mission answers previous questions and raises new ones as well. I’m not sure what surprises VERITAS and DAVINCI +, slated to launch in the late 2020s, will discover in Venus, but I do know that they will discover aspects of the planet that no one ever imagined. Scientists and mission teams around the world have worked hard to achieve a “Venus Decade,” and it is starting to pay off. In fact, just a week after NASA’s announcement, the European Space Agency also announced its plans for a Venus mission. With these new missions, I guess – my hope – that we are at the start of a new golden age of Venus exploration.


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