Evidence mounts for habitability of Venus-like worlds

Climate models show exoplanets like Venus could hold oceans under the right conditions. Richard A. Lovett reports.

Venus may once have held watery oceans.
Venus may once have held watery oceans.

Venus-like exoplanets might not be super-heated hothouses, say scientists. Evidence is mounting that even Venus itself could have supported liquid oceans as recently as 750 million years ago, says Michael Way, an atmospheric scientist at NASA’s Goddard Institute for Space Studies in New York City.

Venus is dry now, but based on isotope ratios of hydrogen in its present atmosphere, scientists can calculate how much water it once had, Way said at a NASA-sponsored symposium called “Environments of Terrestrial Planets Under the Young Sun: Seeds of Biomolecules,” in Greenbelt, Maryland.







His model also assumes that the early Venus (and similar exoplanets) had some form of tectonics that, through rock-weathering processes, could recycle volcano-produced carbon dioxide from the atmosphere back into the interior. Otherwise, the planet-warming gas would build up to a point where all of the water evaporates and the planet goes into a superheated state like modern Venus, where surface temperatures are on the order of 450°C.

In fact, Way suggests, the end of Venusian habitability may have been caused not by the slow warming of the Sun, but by massive volcanism, which appears to have covered 80-85 percent of the Venusian surface about 750 million years ago, in the process releasing tremendous amounts of carbon dioxide. “The planet can handle increased [solar energy],” he says. “Probably something else happened, and it probably has to do with the resurfacing events.”

Matthew Weller, a planetary scientist from the Institute for Geophysics at the University of Texas at Austin, who has studied Venusian tectonics, agrees. “The picture that is emerging between Michael’s stuff (atmosphere) and my stuff (interior-to-atmosphere) is that the potential for liquid water and habitability depends on far more than just the distance to the host star,” he says.

Figuring all of this out for exoplanets, he adds, means paying more attention to Venus. “It’s the forgotten planet," he says.

Contrib ricklovett.jpg?ixlib=rails 2.1
  1. https://cosmosmagazine.com/space/venus-may-have-hosted-life-researchers-say
  2. https://astrobiology.nasa.gov/events/environments-of-terrestrial-planets-under-the-youn/
  3. https://www.vanderbilt.edu/AnS/physics/astrocourses/AST101/readings/water_on_venus.html
Latest Stories
MoreMore Articles