A Fleet of robot spaceships to descend Venus in a few years and began exploring the most inhospitable worlds in the solar system. One spacecraft will crash through the planet’s extremely dense – and very hot – atmosphere while the other two orbit above thick acid clouds that cover each other. Venus and use the state-of-the-art radar telescope to observe the terrain below.
Such an investigation is a tremendous renewal of interest in Earth’s closest neighbour. For more than a decade, the American and European space agencies have been neglecting the planet – only for three new Venus missions to be announced in the first few days of June.
Håkan Svedhem, former project manager for previous European planetary exploration, Venus Expressscience journal word nature last week: “Venus is a planet forgotten for too long.”
The goals of the new missions – NASA’s Veritas and Davinci + probes and Europe’s EnVision satellites – are simple. They want to know why Earth’s twin planet is so fundamentally different from our own world.
As astronomers knew at the start of the “space age” in the 1960s, the two planets were the same size and had the same age, composition, and orbit around the sun. Beneath the thick clouds of Venus there is a suspicious ocean or forest. So, in the 1970s and 1980s, a number of robotic probes were sent by the American and Soviet space agencies to uncover the truth.
They reveal a world that is a vision of hell. Venus was found to have a surface temperature of 475°C, which is hot enough to melt lead. At the same time, the atmospheric pressure at its surface is 93 bar, which is equivalent to one kilometer under the earth’s oceans. Soviet probes that landed on Venus in the 1970s and 1980s could only transmit data from the planet for a short time – two hours was their best time – before heat and pressure crushed them.
It was also found that Venus was covered in thick clouds of sulfuric acid. In contrast, our own world has oceans of liquid water, clouds and ice sheets and supports countless living things in their seas, on land and in the sky. The differences between the two planets, despite their superficial similarities, are stark.
And the main cause of these very different conditions is explained by the large amount of carbon dioxide that has accumulated on Venus. This has trapped solar radiation and triggered the greenhouse effect out of control, making the effects of the climate crisis that are now disrupting weather patterns and melting Earth’s ice sheet smaller.
How does this accumulation of carbon dioxide occur, scientists ask. Is Earth lucky or Venus just unlucky? Is it normal for orbiting planets like Venus and Earth to develop thick atmospheres of carbon dioxide that trap solar radiation and trigger a runaway greenhouse effect – or is it just a one-off development in Venus’ case?
“This is a key question and has important implications, not only for understanding how life emerged and evolved on Earth,” said Oxford University physicist Colin Wilson. “They also impact the search for habitable planets in orbit around other stars in our galaxy.”
Now, astronomers hope to find promising planets that could support life elsewhere in the galaxy by discovering small rocky worlds — like Earth — orbiting stars at distances where water would likely exist in liquid form. But judging by the only other world in our solar system that is in such a zone – Venus – this may not be a very promising place. In other words, if Earth were the exception and Venus the norm, we might find such planets far less favorable as hosts for extraterrestrial life.
This point was emphasized by Giada Arney, Principal Research Assistant for NASA’s Davinci + investigation: “Our study of the evolution of Venus can help us better understand how habitable worlds are distributed elsewhere in the universe and how habitable planets generally move together” It’s possible that Venus is in the wrong place. It’s closer to the Sun than Earth – 67 million miles versus 93 million miles – making it slightly warmer than it was when the solar system was born 4.5 billion years ago, and as a result, water vapor in its atmosphere never condenses in the oceans as it did on Earth, where our oceans play a key role in absorbing carbon dioxide and preventing runaway greenhouse warming.
Other evidence suggests that Venus may have had liquid water on its surface at one time and another event started the rampant warming that now surrounds the planet. Three new probes will try to uncover clues as to what they might be. “Studying the planet’s surface will be very important,” Wilson said. “The US Magellan probe – which landed on Venus in 1989 – used radar to peer through the clouds and gave us a beautiful global map of Venus, revealing volcanoes and rough surfaces that have clearly been through a lot of turmoil. But that’s just a snippet.
“For example, we don’t know if this volcano is still active. The new spacecraft will apply 21st century radar technology to Venus and give us a much more dynamic picture of the planet.”
This is supported by astronomer Professor Jane Greaves of Cardiff University. “Several instruments such as radar and mass spectrometers have been used to study Venus in the past, but their technology is much better and more sophisticated today. We will be able to examine more deeply and identify the molecule more easily.”
Both NASA’s Veritas and the European Space Agency’s EnVision will be involved in mapping the surface of Venus from orbit high above its acid clouds. Instead, Davinci+ will carry a small probe to the planet that will release it to fall through its atmosphere and sample its gaseous constituents every 100 meters as it descends. These measurements will be crucial in understanding the origins of Venus’ atmosphere and providing clues about how it evolved.
By studying concentrations of deuterium, an isotope of hydrogen, for example, it should be possible to determine how much water was once present on Venus, while analysis of noble gases – such as argon and neon – in the atmosphere could also allow scientists to determine whether the planet ever supported water. liquid – data that will be crucial in providing clues about Venus’ path to the dark side.
“It’s amazing how little we know about Venus,” said Tom Wagner, a scientist in NASA’s Discovery Program.
“However, the combined results of this mission will tell us about the planet from the clouds in the sky to the volcanoes on its surface to its core. It’s as if we have rediscovered the planet.”
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