IT WAS born at the same time as the Earth but, as it grew, something happened to turn Venus into our “evil twin”. There are some scientists who believe it was once capable of supporting life, but today our nearest neighbour has one of the most hostile environments in the solar system, with rainclouds of sulphuric acid, crushing pressures, ferocious winds and temperatures approaching 500C.
Exactly why the planet, named after the Roman goddess of love, turned into such a vision of hell has been a mystery to humankind. However, the arrival yesterday of the Venus Express space probe in the planet’s orbit offers us the hope of finally working out exactly what happened.
As the Venusian atmosphere is almost entirely made up of carbon dioxide, a greenhouse gas, scientists on the European Space Agency (ESA) mission believe studying it could help shed light on global warming on Earth.
The tension was palpable at mission control in Darmstadt, Germany, yesterday morning, as the scientists waited to see whether Venus Express would successfully perform what was described as a “handbrake turn”, to swing into orbit around the planet.
Then came the signal they had all been waiting for – a simple green line on their computer screens indicating that the craft had slowed down for the drop into orbit, rather than plunging off into outer space – which provoked a frenzy of cheers and applause.
Shortly afterwards came the news that an antenna which will provide pictures and communication to the Earth had successfully deployed.
Dr Paolo Ferri, the flight operations director, describes the moment he realised the craft had made it into orbit: “It was wonderful. It was different from the other phases, like the launch, because we had actually done everything on Friday and were just watching things happen and hoping they would go right, with very little chance to intervene in case things went wrong.
“It was tense and a bit frustrating. But when we saw everything was going wonderfully, it was a great relief.
Professor Fred Taylor of Oxford University is one of the mission’s founding fathers, and drummed up support for a new study of the “forgotten planet” when other scientists shifted their interest to Mars.
“There is very much a feeling that the really difficult hurdle has been passed,” he says. “The tension in the control room was just wonderful. It felt like you were in the actual spacecraft.
“People have taken the view that the European planetary programme is coming of age with this mission, and that Europe is now a major player in this field.”
The £153 million Venus Express, which is virtually the same as the Mars Express craft that has been providing spectacular images of Mars for three years, took off on a Russian Soyuz rocket from Baikonur in Kazakhstan last November, travelling 400 million kilometres to reach Venus.
It will orbit the Venusian poles at a distance of between 250 and 66,000km, collecting data with a range of instruments designed to build on observations from previous missions.
The mission will last just two Venusian days – which corresponds to 486 days on Earth – although there are hopes that extra funding can be secured to double this to four Venusian days.
The instruments onboard include spectrometers to measure temperature and analyse the atmosphere, and a special camera to find out whether Venus’s many volcanos are active or not.
The make-up of the atmosphere, the extent of magnetic fields and radiation will be studied, and radio waves will be bounced off the planet, to examine the surface, atmosphere and ionosphere.
A range of pictures, using ultraviolet, infrared and visible light, will also be taken. All this would have been lost had the flight control team’s preparations some three days before not been right on the mark.
In about a month, after instruments on the spacecraft have been deployed, tested and calibrated, the first data should start to come in, giving scientists a fresh understanding of this wholly alien world, which Prof Taylor and others on the project believe could lead to a greater understanding of the potential threat posed by global warming.
“Venus really is Earth’s twin, born at the same time and of similar size but behaving in a different way,” he says.
“Some of the reasons why Venus acted the way it did may explain some of the problems we are having on Earth. There were so many unanswered questions about Venus.”
The last mission to Venus was NASA’s Magellan probe, launched in 1989. It completed more than 15,000 orbits of the planet between 1990 and 1994, mapping almost all of it, revealing towering volcanoes, gigantic rifts and sharp-edged craters.
Watching yesterday’s return to Venus via a live satellite link, Dr Andrew Coates, of the Mullard Space Science Laboratory in Dorking, Surrey, finds it hard to contain his euphoria.
“For now, so far so good. We are about to enter a new chapter of exploration,” he says. “While Venus Express was getting close to Venus we had to slow it down by 3,000kph, and it used a hand-brake turn to slow it and trap it around our target planet. Without this critical manoeuvre, Venus Express would literally have been lost in space.”
Dr Coates is among those hoping that studying a different planet’s climate will help teach scientists about our own. It is thought Venus once had water on its surface but that this boiled away as the temperatures rose to their present ferocity.
“Venus is our nearest neighbour, but it is also our nightmare,” he says. “We will try to find out why it’s like that. We will be able to study the lower atmosphere and Venus for the first time. Venus has evolved into our twisted sister or evil twin and we [can now] try and see why.”
ESA’s scientific director, David Southwood, adds: “We want to learn about the mistakes of Venus, for Earth’s sake.”
He is now looking forward to a new age of European space exploration.
“Venus is one more planet checked off the list, but it’s important for us to do more planetary exploration,” he says.
“We are planning to go back to Mars, and Mercury, one of the most mysterious planets. These plans may seem far away but there’s a lot more in our universe to be discovered. We need to put more emphasis on exploring beyond the solar system, back to the very beginning of the universe with the Big Bang. The next major mission will be increasing investigation into astronomy for the next few years. It’s part and parcel of bringing together the whole picture of the place where we live, and finding out how we turned up here.
“That’s the kind of question we’re facing on a grand scale in science. It’s essential to go into space to find the answers. Venus is just one more step [along] that route.”
Professor Colin Pillinger, of the Open University, knows all too well the feelings of anxiety associated with space missions: he was forced to wait for days until it became clear that his Beagle 2 Martian lander had not made a safe landing and was not going to make contact with Earth.
“When spacecraft go through these manoeuvres, it is always a little nerve-racking. You always worry it won’t happen,” he says.
It was hoped Beagle 2 might find signs of life on Mars and, though that may seem an unlikely outcome on Venus, Prof Pillinger says it cannot be ruled out: “It’s not the sort of place you would expect to find life. It would be very unusual life if you found anything that could survive on Venus, but there is life on Earth in very strange places – extremophiles that can withstand great pressures at the bottom of the oceans, cope with all kinds of salt concentrations, alkali or acid.
“Who knows? I wouldn’t bet on it. But one needs to look at all the possibilities.”
EARTH vs VENUS
1 EARTH is further away from the sun than Venus at 149,600,000km or 92,957,000 miles. It is also slightly larger, with a diameter of 12,750km (7,920 miles).
2 A day on Earth takes 23 hours and 56 minutes, while a year lasts 365 days.
3 Earth’s average temperature is about 15C and its atmosphere is largely nitrogen (77 per cent) and oxygen (21 per cent). Atmospheric pressure on Earth is about 100 kilopascals.
4 At higher altitudes and latitudes, water freezes to form snow and ice. It also runs as a liquid and appears in gas form as mist or clouds.
5 The strongest sustained winds found on Earth have been measured at about 190 miles per hour. These are extremely unusual and a hurricane is classed as a storm of 73mph or stronger.
6 Water is abundant on Earth, with seas and oceans making up 71 per cent of the planet’s surface.
7 The centre of the planet is made of a solid iron core, surrounded by molten magma, which can breach the surface crust in volcanos.
8 The Earth’s terrain is highly variable, with deep ocean trenches and high mountain ranges. Challenger Deep in the Mariana Trench is the deepest point at 10,924 metres or 35,840 feet below sea level.
9 There are several large mountain ranges on Earth, including the Himalayas in Asia, the Rocky Mountains and the Andes in North and South America and the Alps in central Europe. The Earth’s highest peak, Mount Everest, is 29,035ft above sea level, which is almost 10km high.
1 VENUS lies some 108,200,000km, or 67,232,000 miles, from the sun and is just over 12,100km (7,520 miles) in diameter.
2 Venus spins extremely slowly compared to the Earth, and in the opposite direction. One full revolution of the planet takes 243 Earth days. A year on Venus – the length of time the planet takes to travel round the sun – is shorter than the length of its day, at 225 Earth days.
3 The average surface temperature on Venus is more than 30 times warmer than Earth at 465C. This is at least partly because of the massive amount of carbon dioxide present in the planet’s atmosphere. The so-called greenhouse gas makes up around 96 per cent of Venusian “air”, with nitrogen accounting for just 3 per cent.
The atmospheric pressure of Venus is 9,300 kilopascals at ground level, which is about 93 times the atmospheric pressure found at sea level on Earth, and equivalent to the pressure at a depth of 1,000 metres in Earth’s oceans.
4 Scientists believe that the Venusian “mists” may be made of metals such as iron pyrites (or fool’s gold) and tellurium, which have been vaporised because of the extreme heat and pressure on the planet. These compounds can also fall as snow on upland areas.
5 Winds on the cloud tops run at more than 215mph.
6 It is thought that Venus once had large amounts of water, much like Earth, but that it boiled away, leaving the planet extremely dry.
7 The centre of the planet is thought to be similar to Earth’s: an iron core with a molten-rock mantle.
8 The landscape of Venus is mostly a “gently rolling plain”, with little in the way of mountain ranges. However, there are two large upland areas, one about the size of Australia in the northern hemisphere, called Ishtar Terra, and another called Aphrodite Terra, which is about the size of South America, on the equator.
9 Venus’s tallest mountain is called Maxwell Montes, after the Scots physicist James Clerk Maxwell, and it is 12,000 metres (39,370ft) above the planet’s average surface, despite being only 10km (six miles) wide at the base. On Earth, the base would be too narrow to support such a large structure.