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Spacecraft Peeks Under Venus' Veil

A probe sends back images of the planet's south pole, which is shrouded in clouds. The mission could shed light on global warming.

April 14, 2006|Jia-Rui Chong | Times Staff Writer

The European Space Agency's Venus Express spacecraft returned the first images of the planet's south pole Thursday, revealing a tempestuous sky of sulfuric acid clouds whipped by winds of more than 200 mph.

Scientists long have been hampered from peering into Venus' atmosphere because a thick haze enshrouds the planet.

But the spacecraft's infrared and visible cameras were able to capture two slices of the atmosphere at 34 and 40 miles above the surface.

"We have been able to see the top 1% of the atmosphere," said Kevin Baines, a planetary scientist at NASA's Jet Propulsion Laboratory in La Canada Flintridge who is one of the lead mission members. "With these [cameras], we see the rest of the 99%.

"People thought Venus was a boring thing to look at," he said. "It looks like a pingpong ball with just white clouds. But these show there really is some structure."

The probe's first pictures were taken from a distance of about 128,000 miles. In the next few weeks, it gradually will tighten its orbit until it is 155 miles from the planet's north pole.

There have been about 20 Russian and U.S. missions to Venus since 1962, but they have provided only snapshots of the planet's atmosphere. Some of the probes managed to make it to the surface but were able to transmit information for only about an hour before they were destroyed, Baines said.

Venus Express, launched last November, will allow scientists to study the planet for at least the next 16 months. It is expected the probe will provide scientists with the first chance to build a three-dimensional model of the planet's atmosphere.

Venus, the second planet from the sun, and the Earth, the third, share similar ages, masses and surface composition. But Venus somehow developed a far denser atmosphere. It has a surface temperature of about 900 degrees Fahrenheit and an atmospheric pressure 90 times that of Earth.

"Venus is extremely inhospitable for life, whereas Earth is a great place to live," said project manager Don McCoy. "If these planets were created about the same time, why would Earth take on such a different character?"

Venus developed the most powerful greenhouse effect in the solar system as layers of carbon dioxide trapped heat from the small amount of sunlight that pierced the clouds. Studying this "runaway" greenhouse effect could illuminate the possible course of global warming on Earth.

Scientists also would like to find out how air circulates in the planet's atmosphere. They have been baffled by how winds can whip around the planet at a rate 60 times faster than the planet rotates, and are particularly interested in what happens around the poles, which seem to be the center of the spiraling wind and heat.

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