Blissfully between two extreme celestial bodies, resides our own relatively temperate planet. Venus is a blistering inferno while (image left of early Mars) is frigid tundra. Perhaps our intrasolar neighbors can provide valuable insights in humankind’s efforts to combat global warming, and the way that climate catastrophes affect planets.
David Grinspoon, curator of astrobiology at the Denver Museum of Nature and Science, and one of Venus Express's interdisciplinary scientists, believes that scientists need to pay attention to our neighboring planets.
"It seems that both and Venus started out much more like Earth and then changed. They both hold priceless climate information for Earth," says Grinspoon.
Planetary scientists want to turn the clock back using climate change models to understand why and how Venus morphed from its former Earth-like conditions into a hellish inferno.
Scientists believe that the planet experienced a runaway greenhouse effect as the Sun gradually heated up. Astronomers believe that the young Sun was dimmer than the present-day Sun by 30 percent. Over the last 4 thousand million years, it has gradually brightened. During this increase, Venus's surface water evaporated and entered the atmosphere.
"Water vapor is a powerful greenhouse gas and it caused the planet to heat-up even more. This is turn caused more water to evaporate and led to a powerful positive feedback response known as the runaway greenhouse effect," says Grinspoon.
As Earth warms in response to manmade pollution, it risks the same fate. Reconstructing the climate of the past on Venus can give scientists a better understanding of how close our planet is to such a catastrophe. However, determining when Venus passed the point of no return is not easy. That's where ESA's Venus Express comes in.
The spacecraft is in orbit around Venus collecting data that will help unlock the planet's past. Currently, Venus is losing gas from its atmosphere. Venus Express is measuring that rate of this loss and the composition of the disappearing gas. It also monitors the movement of clouds in the planet's atmosphere, which reveals the way Venus responds to the absorption of sunlight. Energy from the Sun is what powers the atmosphere to move. The craft will also chart the amount and location of sulphur dioxide in the planet's atmosphere, which is a greenhouse gas released by the planet’s volcanoes.
"Understanding all of this will help us pin down when Venus lost its water," says Grinspoon. That knowledge can feed into the interpretation of climate models on the Earth because although both planets seem very different now, the same laws of physics govern both worlds.
Understanding Mars' past is equally important. ESA's Express is currently investigating the fate of the Red Planet. Smaller than the Earth, is thought to have lost its atmosphere to space. When Martian volcanoes became extinct, so did the planet's means of replenishing its atmosphere turning it into an almost-airless desert.
"What happened on these two worlds is very different but either would be equally disastrous for Earth. We are banking on our ability to accurately predict Earth's future climate," says Grinspoon.
Our neighbors may offer important insights into the future of our own planet and help us develop the correct climate models—which are the weapon of choice for the climate change specialist.
We need Earth’s scientists to get the climate models right. If we’re off in our predictions, we may not be able to effectively treat the problem—or could even make things worse, which is something we can’t afford to do.
Posted by Rebecca Sato
* This post was adapted from a news released issued by the European Space Agency.
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