Saturday, December 01, 2007

our celestial twin?


Interesting news from the folks at the European Space Agency who are running the Venus Express spacecraft mission: It appears that Venus and Earth are looking more and more like they may be twins separated at birth!

Venus Express has been orbiting our sister planet since April 2006, but the first solid chunk of data from the mission is just starting to be released now (it takes a while to compile and analyze). Venus was an early target for interplanetary exploration due to its relative proximity to Earth back in the 1960s and 70s. The Soviet Union with its Venera spacecraft and the U.S. with its Mariner probes made dozens of attempts at orbit insertions and landings—quite a few of which were ultimately successful. From those missions we found out that Venus has a similar internal structure to Earth. It also has similar geological activity—such as volcanoes and plate tectonics. The most obvious difference between the two is that Venus has a thick, goopy atmosphere of noxious fumes, mostly carbon dioxide, that you can't see through with the naked eye (the image above is a radar image taken by NASA's Magellen spacecraft). Nevertheless, the early missions allowed us to see the surface for the first time.

Today, Venus Express is clueing us in to the fact that Venus may have looked a lot more like Earth in its distant past. The newest findings from present day include signs of lightning and temperature swings that are a lot more Earthlike than they thought Venus had the capacity for. Mission scientists believe Venus probably had large amounts of liquid water on its surface at one point, until it suddenly started evaporating into the atmosphere. Once there, it was broken down by the sun's rays into carbon dioxide (which hung around) and hydrogen (which escaped into space). This caused an out-of-control greenhouse effect that probably caused Venus to turn into a hellish planet with temperatures of around 800° F that probably no life form could survive on. While the Earth is much farther away from the sun than Venus is, the natural question, of course, is whether or not our steady dumping of carbon dioxide into our own atmosphere could someday turn Earth into a Venuslike place. Here's hoping we'll never know...

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