Europe is sending a probe to Venus, teaming up with NASA to rocket 3 missions to the planet in the next 15 years

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An illustration of the EnVision spacecraft with Earth (left) and Venus (right).

After decades of gazing longingly at Mars, the world’s space agencies are finally turning back to look at Venus.

Last week NASA announced that it had picked two new missions to go to Venus – one, called VERITAS, to orbit the planet and another, called DAVINCI+, to plunge to its surface. Now the European Space Agency (ESA) is throwing its hat in the ring.

The ESA revealed Thursday that it’s sending its own probe to Venus – an orbiter called EnVision. The mission aims to study how the planet’s atmosphere, surface, and interior interact to create the infernal pressure cooker it is today. Together, the three probes spell a renaissance in Venutian science.

“A new era in the exploration of our closest, yet wildly different, solar system neighbor awaits us,” Günther Hasinger, ESA Director of Science, said in a press release. “Together with the newly announced NASA-led Venus missions, we will have an extremely comprehensive science program at this enigmatic planet well into the next decade.”

The NASA missions are set to launch between 2028 and 2030, and the ESA probe sometime in the early 2030s.

Venus’ climate became hellish long ago, but it may have hosted life

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A composite image of Venus from NASA’s Magellan spacecraft and Pioneer Venus Orbiter.

Venus used to be a lot like Earth. The two planets are about the same size, and they’re made of the same material. Scientists think Venus could have even had oceans in the distant past.

But something happened that drastically changed Venus’ climate. Today it’s the hottest planet in our solar system, thick with yellow, heat-trapping clouds of sulfuric acid. Its average surface temperature is a blistering 880 degrees Fahrenheit (471 degrees Celsius) – hot enough to melt lead – and its crushing air pressure is more than 90 times that of Earth’s.

The upcoming missions could help scientists understand how Venus became such an extreme environment, whether it was hospitable to life, and whether or not its volcanoes are still erupting.

The world’s interest in Venus was rekindled in September, when a new study suggested the planet’s clouds could harbor microbial aliens.

That’s because researchers found traces of phosphine – a gas typically produced by microbes on Earth – in the upper reaches of Venus’ clouds. However, a follow-up study suggested those trace elements weren’t phosphine, but rather sulfur dioxide, casting doubt on the idea that Venus could be habitable.

These new missions could help settle that debate.

“It is astounding how little we know about Venus, but the combined results of these missions will tell us about the planet from the clouds in its sky through the volcanoes on its surface, all the way down to its very core,” Tom Wagner, a NASA Discovery Program scientist, said in a statement about the NASA missions. “It will be as if we have rediscovered the planet.”

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A NASA probe detected a strange radio signal in Venus’ atmosphere last year. Astronomers have figured out where it came from.

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NASA’s Parker Solar Probe snapped an up-close view of Venus when it flew by the planet in July 2020.

  • NASA’s Parker Solar Probe detected a strange radio signal while flying by Venus in July.
  • The probe flew through Venus’ upper atmosphere, where such signals naturally occur, to collect data.
  • The data show Venus’ atmosphere has thinned, a process linked to solar activity.
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During a close flyby of the planet Venus on July 11, 2020, NASA’s Parker Solar Probe detected something odd.

As it dipped just 517 miles above the Venusian surface, the probe’s instruments recorded a low-frequency radio signal – a telltale sign that Parker had skimmed through the ionosphere, a layer of the planet’s upper atmosphere.

This was the first time an instrument had been able to directly record measurements of Venus’ upper atmosphere in nearly three decades, and the data gives us a new understanding of how Venus changes in response to cyclic changes in the sun.

“I was just so excited to have new data from Venus,” Glyn Collinson, an astronomer at NASA’s Goddard Space Flight Center, said in a press release.

According to a recent study by Collinson’s team, Venus’ upper atmosphere was an order of magnitude thinner last year than it was in 1992 – the last time scientists were able to collect data from the planet’s atmosphere.

Venus’ thick, hot atmosphere makes it hard to explore

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The surface of Venus as seen on September 16, 2010.

Venus is similar to Earth in size and composition, yet crucially different: It’s a toxic, scorching hot hell-world that is likely completely inhospitable to life as we know it.

How the two planets could have developed into such radically different beasts is of profound interest to planetary scientists and astrobiologists searching for other habitable worlds in the galaxy.

Yet missions to explore Venus have been relatively few. There’s not much point sending landers; they can’t survive the planet’s 864-degree-Fahrenheit (462-degree-Celsius) surface.

Sending orbiting probes is also considered problematic due to the incredibly thick atmosphere of carbon dioxide and sulfuric acid rain clouds that make it hard to tell what’s happening on the surface.

For these reasons, Venus hasn’t been a popular target for dedicated missions in some time (Japan’s Akatsuki orbiter being the recent exception), and a lot of our recent data has come piecemeal, from instruments with other primary objectives, like the Parker Solar Probe.

As the Parker probe conducts its mission to study the sun in close detail, it’s been using Venus for gravity assist maneuvers – slingshotting around the planet to alter its velocity and trajectory. It was on one of these gravity assist flybys that the probe’s instruments recorded a radio signal.

Collinson, who has worked on other planetary missions, noted an odd familiarity that he couldn’t quite place in the shape of the signal.

“Then the next day, I woke up,” he said, “and I thought, ‘Oh my god, I know what this is!'”

It was the same kind of signal recorded by NASA’s Galileo probe when the space skimmed through the ionospheres of Jupiter’s moons. The ionosphere is a layer of atmosphere where solar radiation ionizes atoms, resulting in a charged plasma that produces low-frequency radio emission that scientists can detect.

Once the researchers realized the signal was ionospheric plasma, they were able to use the signal to calculate the density of the Venusian ionosphere, and compare that density to similar measurements taken in 1992. Fascinatingly, the ionosphere was an order of magnitude thinner in 2020 than it was in 1992.

The sun wreaks havoc on Venus

The team believes that thinning has something to do with solar cycles. Every 11 years, the sun’s magnetic poles swap places: south becomes north and north becomes south. It’s not clear what drives these cycles, but we do know that the poles switch when the magnetic field is at its weakest.

When the sun’s magnetic field is weak, there’s fewer instances of sunspots, solar flares, and coronal mass ejections – when the sun releases plasma and bits of its magnetic field into space. This period of minimal activity is aptly called the solar minimum.

Once the poles have switched, the magnetic field strengthens, and solar activity increases to a maximum before subsiding again for the next polar switch.

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A NASA image of the solar surface.

Measurements of Venus from Earth suggested that Venus’ ionosphere was changing in sync with the solar cycles, growing thicker at solar maximum and thinner at solar minimum. But without direct measurements, it was difficult to confirm – until the Parker probe’s recent flyby.

The 1992 measurement was taken at a time close to solar maximum; the 2020 measurement close to solar minimum. They were both consistent with the Earth-based measurements.

“When multiple missions are confirming the same result, one after the other, that gives you a lot of confidence that the thinning is real,” Robin Ramstad, an astronomer from the University of Colorado, Boulder, said in the release.

Exactly why the solar cycle has this effect on Venus’ ionosphere is unclear, but there are two leading theories.

The first is that the upper boundary of the planet’s ionosphere could be getting compressed to a lower altitude during solar minimum, which prevents atoms ionized on the day side from flowing to the night side, resulting in a thinner night side ionosphere. The second is that Venus’ ionosphere leaks into space at a faster rate during solar minimum.

Neither of these mechanisms could be ruled out by the data collected by the new Parker probe, but Collinson’s team hopes that more observations and future missions to Venus might be able to clarify what’s going on.

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