New research, led by scientists from the NASA Goddard Institute for Space Studies, suggests Venus and Earth closely resembled each other during the early days of the Solar System, between one and two billion years ago. Venus, now the hottest planet in our Solar System, engulfed in a thick toxic sulphuric acid cloud layer with strong atmospheric pressure, may have been habitable, with mild climate conditions and oceans, as well.
Venus, similar to our planet in size, density, and composition, also exhibits an unusually high ratio of deuterium versus hydrogen, indicating it had likely contained abundant amounts of water.
“It’s one of the big mysteries about Venus. How did it get so different from Earth when it seems likely to have started so similarly? The question becomes richer when you consider astrobiology, the possibility that Venus and Earth were very similar during the time of the origin of life on Earth,” said David Grinspoon of the Planetary Science Institute in Tucson, Arizona.
The scientists utilized a model of environmental conditions, used to explore the Earth's climate change, to simulate conditions on early Venus. They have produced four versions of the planet with subtle variations of the sun radiation received by the planet and the duration of a day. They've put in 10% of the Earth's ocean volume over approximately 60% of the surface and tracked how each version evolved over time.
Results showed Venus might have been very similar to Earth during the early days, and it may have remained habitable over a long time. One of the best-simulated versions had conditions of moderate temperature, thick cover of clouds and occasional light snowfall. If there were any life forms present, the later-evolving conditions of boiling oceans and volcanoes have dramatically changed its landscape approximately 715 million years ago.
“There’s great uncertainties in understanding Earth, not only its climate history but the history of how life began. There’s no reason that life on this world would not have existed in these oceans. But that’s about all you can say," said Michael Way at the NASA Goddard Institute for Space Studies in New York City.
“Both planets probably enjoyed warm liquid water oceans in contact with rock and with organic molecules undergoing chemical evolution in those oceans. As far as we understand at present, those are the requirements for the origin of life,” added Grinspoon.
Future exploration of the planet should search for water-related erosion near the planet's equator, a sign which could prove the existence of simulated oceans. Similar signs have already been found on Mars' surface.
The researchers suggest more simulations should be run, in search for other alternative planet's pasts, for example of a desert landscape, or one immersed in water as on Earth, to discover which one could develop to a present situation on Venus.
The study holds the potential for helping the scientists in their quest for exoplanets. It Venus was, indeed, once able to sustain life, other planets close to their stars, may have been too.
- "Was Venus the First Habitable World of our Solar System?" - Michael J. Way, Anthony D. Del Genio, Nancy Y. Kiang, Linda E. Sohl, David H. Grinspoon, Igor Aleinov, Maxwell Kelley, Thomas Clune - Geophysical Research Letters (2016) - arXiv:1608.00706
Featured image: A global view of the surface of Venus, centered at 90 degrees east longitude. Image credit: NASA/JPL
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