Today's Venus is Cool: Relatively Speaking

"Hellish Venus Atmosphere May Have Had Cooling Effect"
Space.com (September 21, 2010)

"It may seem downright bizarre, but a new model of Venus' super-hot atmosphere suggests its greenhouse gases may actually be cooling the planet's interior.

"These gases initially cause Venus' temperature to rise, but at a certain threshold, they can trigger dynamic processes – which researchers call 'mobilization' – in the planet's crust that cool the mantle and overall surface temperature, researchers found...."

"...Noack and co-author Doris Breuer built a one-of-a-kind Venus computer model in which the planet's hot atmosphere was paired with a 3-D model of the interior.

"Unlike on Earth, Venus' high temperatures have a much bigger effect on the rocky surface, which ultimately loses its insulating qualities, the researchers said.

" 'It's a little bit like lifting the lid on the mantle: The interior of Venus suddenly cools very efficiently and the rate of volcanism ceases,' Noack said. 'Our model shows that after that "hot" era of volcanism, the slow-down of volcanism leads to a strong decrease of the temperatures in the atmosphere.'..."

Even today's 'cool' Venus is hot by our standards. The average surface temperature is 860 degrees Fahrenheit / 460 degrees Celsius.

The researchers' model shows that the current 'cool' Venus, with subdued volcanic activity - could still have active volcanoes in a few spots. Which is a pretty good match with what's been observed.

If the Noack - Breuer model is a fairly accurate description of how Venus has been shedding heat, this looks like a sort of feedback loop we see in our endocrine system - or the thermometer and furnace in houses.

Oceans on Venus; a Very Long Time Ago; Maybe

"Oceans on Ancient Venus, Study Suggests"
Space.com (July 14, 2009)

"Venus may once have been more Earth-like, with volcanic activity and an ocean of water, a new map of the toasty planet's southern hemisphere suggests.

"The map comprises over a thousand individual images, recorded between May 2006 and December 2007 by the European Space Agency's Venus Express spacecraft. It gives astronomers another tool in their quest to understand why Venus is so similar in size to Earth and yet has evolved so differently.

"Because Venus is covered in clouds, normal cameras cannot see the surface, but Venus Express used a particular infrared wavelength to see through them.

"Although radar systems have been used in the past to provide high-resolution maps of Venus's surface, Venus Express is the first orbiting spacecraft to produce a map that hints at the chemical composition of the rocks...."

The article discusses, briefly, the possibility that the platforms on Venus may be similar, chemically, to the platforms we call continents on Earth. What's been found so far suggests that at least part of Venus' 'continents' are made of granite.

Robotic landers touched down on what may have been the ocean floors of Venus, and found the sort of basaltic rock we find under the organic stuff that coats the bottoms of Earth's oceans.

This article is a pretty good 'snapshot' of what's known about Venus, what's being discovered, and speculation about this near-twin of Earth.

More, about the (very remote) chance of finding living microbes in the clouds of Venus:

• "Microbes Could Travel from Venus to Earth"
  Space.com (August 11, 2008)
• "Life Zone on Venus Possible"
  Space.com (February 11, 2003)

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Related posts, at

• "A Serious Search for Other Worlds, Life, and - Maybe - Extra-Terrestrial Intelligence"

Cloud Cities of Venus

"Colonizing Venus With Floating Cities"
Universe Today (July 16, 2008)

"Seemingly, people in the space community have a tendency to push the boundaries of thought about all the possibilities that await us in the universe. Case in point: Geoffrey Landis. Landis is a scientist at NASA's Glenn Research Center who writes science fiction in his spare time. Last week Landis shared with us his ideas for using a solar powered airplane to study Venus. This week, Landis goes a step farther (actually, several steps farther) with his ideas about colonizing Venus. Yes, Venus, our hot, greenhouse-effect-gone-mad neighboring planet with a crushing surface pressure that has doomed the few spacecraft that have attempted to reach the planet's mysterious landscape...."

It's not all that crazy an idea.

It looks like we have the technology to build those cities now.

I think the limiting factor will be economic. Somehow, it would have to be worthwhile to go to Venus and build a city about 50 kilometers up in the clouds. The NASA scientist may have made a useful suggestion: "Just think of the great pictures you could get," said Landis. Tourism, anyone?