For a long time, many imagined conditions on Venus to be similar to Earth. But space probes have since discovered a burning hell instead of a tropical paradise on the planet’s surface. The first European mission to Venus, our closest neighbour, helps explain some of the reasons for this hostile environment.
Spring is the season when nature awakes from a cold and dark winter.
The warmth of the sun shining high in the sky brings nature and Man back to life.
Since ancient times, this season has been linked to beauty and love.
These virtues lent their name to a celestial object that resembled Earth so much it was believed to be our planet’s twin sister.
Håkan Svedhem, Venus Express Project Scientist, ESA: ”The planet Venus got its name from the goddess of love and beauty Venus. And it’s of course a very beautiful planet – just as the goddess is beautiful. But Venus can also be a hellish place.”
Many imagined Venus as some kind of tropical paradise.
Dimitri Titov, Science Coordinator for the Venus Express mission: ”A tropical paradise. That’s what people imagined Venus to be at the start of the 20th century. As it’s quite near to us, people expected to find a similar environment there – until the first space flights to Venus proved them wrong.”
At the dawn of the space age, Venus, also known as the ‘Morning Star’, was a very popular destination. This interest was fuelled by hopes of finding similar conditions to Earth on Venus, which is the planet closest to us.
Since the early 60s, more than 20 American and Soviet space probes have been sent to Venus.
Unfortunately, the data collected has unveiled a very hostile planet which has proved extremely difficult to study.
Uli Christensen, Planetary Director, Max Planck Institute for Solar System Research: ”You can’t see its surface from the outside, because Venus is covered in a close layer of clouds -which lie at an altitute of about 60 kilometres. They are made up of sulfuric acid and cover the entire planet. You can’t see through them – at least not in visible light.”
This acid cloud blanket has long prevented Man from studying Venus’s complex environment – its atmosphere, its surface, and its geology.
For more than 15 years, following several failed missions, the “Morning Star” and its mysteries seemed forgotten.
But today, the search has resumed, in the hope of finding answers to our own past and future.
Håkan Svedhem: ”Venus is covered by a thick cloud cover which is impossible to look through with a human eye… But now, with the help of modern technology – in infrared wavelenghs – we’re able to look through this cloud cover down to the surface.”
Some of the planet’s secrets have been uncovered by new high-tech equipment onboard the Venus Express mission.
Built around the design of its predecessor Mars Express, the Venus probe was quicker and cheaper to develop.
Dimitri Titov: “Venus Express is the European Space Agency’s first mission to the planet. It’s been orbiting our closest neighbour for three years now, studying its atmosphere, its plasma mantle and its surface”.
Equipped with state-of-the-art instruments, Venus Express has been able to delve into the secrets of the planet’s atmosphere.
Thanks to the stream of data pouring in from the orbit, scientists have been able to explain to some extent why Venus has become so inhospitable compared to its sister Earth.
The Venus Express mission was launched in November 2005.
Each piece of equipment onboard is thoroughly tried and tested before being sent into space.
Here, the ‘Venus monitoring camera’, which spans near-infrared, ultraviolet and visible wavelengths, is being tested in a vacuum furnace which simulates open space conditions.
Dimitri Titov: ”When we travel, we usually have a camera along to take pictures of what we see. Well, scientists do the same when they send a spacecraft to distant planets. There’s a camera just like this one onboard Venus Express.”
The camera’s images show Venus’s atmosphere is even more dynamic than expected.
Influenced by the gigantic hurricane-like vortices at its poles, the upper atmosphere rotates around the planet at a formidable speed, with wind reaching 360 kilometres an hour.
They then drop to almost zero at the planet’s surface.
Håkan Svedhem: ”When you get deeper into the atmosphere and down to the surface, it’s really a hellish place because of the high temperature and high pressure that crushes everything that gets in there and burns it at 460 degrees Celsius.”
With this data, scientists have been able to model the dynamics of the atmosphere on Venus.
They hope that by better understanding what’s going on under Venus’ clouds, they might find out why Earth and Venus’ destinies differed so wildly from the very birth of our Solar System.
Uli Christensen: “It’s thought Venus’ entire surface was completely altered by some kind of sudden and catastrophic event around 500 million years ago, and tremendous lava flows covered the planet’s surface. There’s been a lot of speculation, but we don’t really know what happened.”
Astronomers of the past could be forgiven for suggesting that Venus’s climate was once similar to the Earth’s.
Our sister planet wasn’t always that different.
Håkan Svedhem: “Likely, in the early days of the Solar system Venus may well have had as much water as the Earth had, and of course in that time the climate would have been very different, the temperature much lower. And slowly then, probably because Venus is closer to the Sun, it received more sunlight, the water slowly boiled up and out of the atmosphere.”
What Venus Express has been able to measure is the way Venus is losing its hydrogen and oxygen, which are stripped away by solar winds.
In contrast, the Earth is protected by its magnetic field.
But the slowly rotating Venus doesn’t have such a shield and is therefore gradually losing what’s left of its water.
To make matters worse, water vapor and carbon dioxide trapped inside the atmosphere act as a huge greenhouse ceiling, warming it up and speeding up the process.
Dimitri Titov: “Climate change on Venus is strongly influenced by a very powerful greenhouse effect, like the one we have on Earth on a much smaller scale – it only warms up our outside atmosphere by 30 to 40 degrees. However, we should bear in mind that by raising CO2 and water vapor levels in the atmosphere, we could one day have a climate as hostile as the one we see on Venus”.
Although there’s still a long way to go before that happens, perhaps the findings of the Venus Express mission will in some way spark reflexion about climate change on its unlikely twin, planet Earth.