Venus Possibly Had Continents, Oceans

by Nancy Atkinson on January 15, 2009

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Venus.  Credit: NASA

Venus. Credit: NASA


A new look at data gathered from the Galileo spacecraft in 1990 reveals that Venus at one time may have been habitable, with evidence of past continents and oceans. In a flyby of Venus on the spacecraft’s journey to Jupiter, a near-infrared mapping instrument detected signatures which the researchers have interpreted as granite. An international team led by planetary scientist George Hashimoto, at Okayama University, Japan, found that Venus’s highland regions emitted less infrared radiation than its lowlands. One interpretation of this dichotomy, says the team’s new paper, is that the highlands are composed largely of ‘felsic’ rocks, particularly granite. Granite, which on Earth is found in continental crust, requires water for its formation.

The Galileo spacecraft was the first use of infrared to look at Venus. Scientists had believed that only radar could see through the dense clouds of sulfuric acid in Venus’s atmosphere to the surface. “Detecting the surface in the infrared is a breakthrough,” co-author Kevin Baines from JPL was quoted in an article in Nature.

The article also quoted another JPL scientist, David Crisp, who was not involved in this study as saying these new conclusions aren’t supported either by the available data or the team’s own models.

“We understand our paper doesn’t resolve everything,” responds co-author Seiji Sugita, a planetary scientist at the University of Tokyo. Sugita says the next step is to apply their models to data from the European Space Agency’s Venus Express spacecraft, which is already orbiting Venus, and the Japanese Space Agency’s Venus Climate Orbiter, scheduled for launch in 2010.

The possible presence of granite suggests that tectonic plate movement and continent formation may have occurred on Venus, as well as recycling of water and carbon between the planet’s mantle and atmosphere.
Venus is now hellishly hot and dry, with an atmosphere of 96% carbon dioxide and a surface temperature of around 460 degrees C, but some scientists think our neighboring planet may have once have been more like Earth.

Another scientist quoted in the Nature article, geophysicist Norm Sleep of Stanford University in California said Venus might have once been almost entirely underwater. “Although without further geochemical data, he adds, we don’t know whether this early ocean’s temperature was 30 degrees C or 150 degrees C,” he said.

But any ocean on Venus would have lasted only a few hundred million years. As the Sun became hotter and brighter, the planet experienced a runaway greenhouse effect. “Any life on Venus that hadn’t figured out how to colonize the cloud tops a billion years after the planet’s formation would have been in big trouble,” says Sleep.

Sources: Nature, Abstract

About 

Nancy Atkinson is Universe Today's Senior Editor. She also is the host of the NASA Lunar Science Institute podcast and works with Astronomy Cast. Nancy is also a NASA/JPL Solar System Ambassador.

Adam January 15, 2009 at 2:30 PM

The estimated ocean lifetime is for a cloud-free model. The oceans might’ve lasted a biilion or two years longer with a dense cloud deck, so Venus might’ve had oceans until Earth’s Proterozoic – could have oxygen-using Venusian bugs been transported to Earth?

Yael Dragwyla January 15, 2009 at 11:46 PM

Adam — There is plenty of evidence of volcanoes on Venus, and volcano ejecta often reach orbital-plus velocity, so it’s possible that microbes of some kind might have traveled from Venus to Earth aboard rocky volcanic ejecta. :-)

jay January 16, 2009 at 2:21 PM

Yeah,
Good luck developing that theory (@ Yael Dragwyla). Of course I understand it is meant as a joke but this scenario is not very probable. First you would have to have a huge no. of projectiles coming out of the volcanic blast, then you’d have to consider the chances that some of them were lucky enough to gain a trajectory towards earth and not oblivion and lastly that some of them were big enough to come through earth’s atmosphere surviving the burn.
It could happen, as all that there is only a probability, though to varying degrees.
I’d rather find advanced Venetians or martians or a Venus Mars confederacy members bringing ‘seeds’ of life from their planets to start llife on this planet as an experiment. :)

yours truly rotten,
jay

jay January 16, 2009 at 2:23 PM

insert <> before the smiley.

jay January 16, 2009 at 2:23 PM

probable

KevinM January 16, 2009 at 10:57 PM

The point is not to establish the truth, but to allow materialists a way to avoid admitting that life may be spontaneous wherever conditions are right. Therefore we must come up with outrageous theories to show that life must have come from highly uninhabitable volcanic planets spewing rocks millions of miles through a vacuum. That’s far more likely. Not.

marcellus January 17, 2009 at 11:16 AM

I don’t like the volcanic ejecta idea. How could material from that possibly reach the velocity neccesary to escape the planet?

An asteroid impact (a big one) could blast the material into the solar system.

Granite January 30, 2009 at 9:24 AM

Very interesting post you wrote. Glad I have stumbled upon it. Cheers!

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