(ORDO NEWS) — Venus may be one of the brightest and most beautiful objects in our night sky, but it’s also extremely inhospitable to life: a toxic, scorching world that humans can never set foot on.
Despite the absence of life, Venus bears some striking resemblances to Earth. Both planets are roughly the same size, mass and density and have a very similar composition. This begs the question: Could Venus ever have been habitable?
A new study has found that if Venus ever had habitable conditions and liquid water on its surface, it was a long time ago and did not last long before the planet turned into a scorched, arid world.
Planetary scientists Alexandra Warren and Edwin Kite of the University of Chicago modeled the history of Venus’s atmosphere to determine the rate and mechanisms of oxygen loss, which in turn showed that if the planet ever had liquid water (which some scientists doubt), it was over 3 billion years ago.
Right now, Venus is extremely dry and low in oxygen. Its atmosphere is 96 percent carbon dioxide and 3 percent nitrogen, with trace amounts of other gases such as sulfur dioxide.
Its atmosphere is extremely dense, with pressures up to 90 times Earth’s, and is eroded by strong winds and sulfuric acid rain.
And because its atmosphere is so thick, the heat just can’t escape. The surface temperature of Venus is the highest of any planet in the solar system, averaging 464 degrees Celsius.
Planetary scientists intend to find out how and why Venus reached its current state. Some climate models suggest that Venus may have had water less than a billion years ago.
The lack of oxygen in Venus’s atmosphere is a little puzzling. If the planet ever had a liquid ocean, that water would have evaporated into the atmosphere as Venus heated up, splitting into hydrogen and oxygen.
Hydrogen would have leaked into space, but oxygen had to stay.
Warren and Kite wanted to know where that oxygen had gone, so they built a model based on habitable Venus.
They plotted water oceans on the surface of Venus, added mechanisms that could contribute to the loss of oxygen, and changed parameters such as the amount of water and the timing of which it could be present.
They ran the model 94,080 times, counting it successful if the levels of dioxide, water, and carbon monoxide at the end of the run were within the upper limits for these gases in Venus’s atmosphere today.
After all, only a small percentage of model launches were successful, and they showed some interesting trends.
One possibility is that the oxygen on Venus bonded with the carbon released by the volcanoes to form carbon dioxide, but that seemed pretty unlikely.
Oxygen will most likely suffer one of two fates: seep into space or linger in oxidizable magma, such as basalt, on the planet’s surface. And the oceans should have dried up 3 billion years ago.
But the magnitude of past volcanic activity on Venus may be limited by the amount of radioactive argon still present in the planet’s atmosphere.
By determining how active Venus’s volcanism has been in the past, the researchers were able to estimate how much water might have been on the planet.
Modeling showed that the depth of the oceans of Venus could be no more than 300 meters. This is less than 10 percent of the Earth’s average ocean depth of 3,688 meters.
Thus, the results reconcile the lack of oxygen in Venus’ current atmosphere with potential early habitable conditions, but the possibility of life still exists.
Future missions may attempt to measure the composition of Venus’s surface to help determine whether the planet could indeed have had life.
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