After a decade, dedicated mission to be sent to Venus
Sunday, 06 November , 2005, 08:54
Paris: Poor Venus. The twinkling planet named after the Goddess of Love has a relationship with Man that is as turbulent as a plot in an airport novel.
For years, her beauty was the stuff of dreams. Then, when that beauty was stripped away to reveal horror, she was abandoned. Now Earth wants to reach out to her once more.
If all goes well, at 03:33 GMT on Wednesday, a Russian rocket will blast off from the Baikonur Cosmodrome in Kazakhstan, taking aloft the first dedicated mission to Earth’s closest neighbour in more than a decade.
Its payload is the Venus Express, an unmanned European Space Agency (ESA) spacecraft that will orbit the planet, scanning it with powerful tools with the goal of understanding its strange, terrifying climate system.
Venus, the second planet from the Sun, is often referred to as our sister. Like Earth, the third rock from the Sun, it is a solid planet.
The planets are also astonishingly similar in size and density, and they were both formed at about the same time—some 4.5 billion years ago, from a thickening cluster of orbiting dust and gas.
“There the similarities end,” ESA notes bleakly. “Venus has no surface water, a toxic, heavy atmosphere made up almost entirely of carbon dioxide with clouds of sulphuric acid, and at the surface the atmospheric pressure is over 90 times that of Earth at sea-level. The surface of Venus is the hottest in the solar system, at a searing 477 Celsius.”
In short: temperate Earth is a paradise, a place of riotous biodiversity; Venus is quite literally a hell. It was not always seen that way.
From the middle of the 17th century, astronomers began to popularise the notion that Venus—so close, so bright, and so warm—was a haven for life.
A catalyst for this perception was France’s Camille Flammarion (1842-1925), whose writings were a huge inspiration for science-fiction novelists of the 1930s and 40s, led by Edgar Rice Burroughs.
Like colonial Africa, Venus was seen as a virgin world with a hot, steamy jungle climate and its inhabitants were exotic, dangerous and sexy—Venus Swamp Girl, a lurid story of the time, being a good example.
All this made Venus prime choice for the first interplanetary missions of the space age.
But what a shock it was, in the mid-1960s, when the pioneering Soviet and US probes sent back data showing a scorching landscape with a suffocating and poisonous atmosphere.
With that, interest in Venus quickly petered out, and mission funding switched to the distant gassy giants which form the Solar System’s big outer planets and to Mars, fourth planet from the Sun.
The last dedicated mission to Venus, other than a flyby, was by the US probe Magellan, from 1989-94.
It used high-quality radar to make detailed maps of Venus’ topography, covering about 98 per cent of the surface. The probe revealed canyons, mountains, volcanoes and volcanic formations as well as craters.
But there are almost no craters that are less than two kilometers in size. Smaller space rocks probably burned up by friction with the thick atmosphere before they reached the surface.
This time around, the prime focus is not on terrain but on Venus’ atmosphere and clouds—aerosol clusters of great complexity and variety, driven by winds that at some heights are faster than the most powerful terrestrial hurricane while at others, close to the surface, are no stronger than a slight breeze.
These clouds are mainly responsible for Venus’ terrible heat, and understanding how they work will shed light on an important aspect of Earth’s greenhouse-gas problem.
Venus clouds reflect back 80 per cent of the radiation from the sun. The clouds themselves absorb another 10 per cent, which leaves just 10 per cent to filter down to the surface.
But the clouds are such an efficient insulator that the surface heat gets stored up, turning the place into a pressure cooker capable of melting metal.
Of special interest is the mechanism that causes these very distinct zones in wind velocity and of enigmatic clouds in the high atmosphere, visible only in ultraviolet light, that somehow absorb half of the solar heat received by the planet.
Venus Express marks Europe’s first exploration of the Evening Star.
The sister to Mars Express, which is in orbit around the Red Planet, carries a payload of seven instruments, ranging from a camera to sensors to measure infrared and ultraviolet light, magnetic fields and space plasma.
After a 162-day hop, the craft is scheduled to arrive off Venus next April, when it will be placed in an elliptical orbit, swooping to as low as 250 km above the surface to a height of 66,000 km.
Venus Express, whose total mission costs are $264 million, has enough fuel to operate for 1,000 Earth days, ESA says on its Web site.