The continued exploration of the planets and moons in our Solar System have revealed many strange things, including that Earth is not the only place with oceans and seas. Mars once had lakes and possibly oceans in the distant past, some of the icy moons in the outer Solar System such as Europa and Enceladus currently have subsurface oceans and seas, and Titan has seas and lakes of liquid methane/ethane on its surface. That’s weird enough, but now there’s a new twist: Venus may have had oceans of liquid carbon dioxide (CO2) in the past.
Even though Venus is insufferably scorching hot today, with crushing air pressure and clouds of sulphuric acid, it has been postulated before that it may have had oceans of water just like Earth—a long time ago—before its nightmarish greenhouse effect took hold. It may have had enough water in the atmosphere to have covered the entire surface with an ocean about 80 feet (25 meters) deep. But whether the planet was ever cool enough for that water to have collected as liquid on the surface is a matter of debate.
But new research suggests that Venus may indeed have once had oceans, but not of water, but of liquid carbon dioxide (CO2). Under the right conditions, carbon dioxide can become “supercritical” where it becomes a fluid with properties of both liquids and gasses.
The new study was led by Dima Bolmatov, a theoretical physicist at Cornell University in Ithaca, N.Y. As Bolmatov notes, “Presently, the atmosphere of Venus is mostly carbon dioxide, 96.5 percent by volume.”
If Bolmatov and his colleagues are correct, massive amounts of that carbon dioxide could have once flowed on the surface as a liquid. If, as theorized, Venus’ atmospheric pressure was once much greater than it is now (already currently 90 times that of Earth), then carbon dioxide could have become supercritical, and pooled on the surface as a bizarre alien version of Earth’s oceans.
As Bolmatov mentioned to Space.com, “This in turn makes it plausible that geological features on Venus like rift valleys, riverlike beds, and plains are the fingerprints of near-surface activity of liquidlike supercritical carbon dioxide.”
There may also have been clusters of gas-like supercritical carbon dioxide which “looked like soap bubbles,” according to Bolmatov. “A bubble of gas that is covered by a thick layer of liquid.”
Carbon dioxide can also become ice, commonly known as dry ice, and as a glass-like solid called carbonia. Dry ice is abundant in the polar caps of Mars and requires extreme cold to form. There is also, of course, carbonated water, where carbon dioxide has been artificially added to water to produce the bubbles and fizziness in soda.
Adding to the weirdness, there was also an earlier report that Venus may have heavy metal frost. In another analogy to Earth, the “frost” would cover mountain peaks like snow, but be composed of heavy metals instead, due to the extremely high temperatures.
Last July, the Venus Express spacecraft completed its aerobraking campaign and raised its orbit for the last time before the coming end of its mission. As of now, the spacecraft is thought to have run out of fuel—as expected—and will soon plummet to a fiery death in Venus’ atmosphere. Venus Express helped revolutionize our understanding of Earth’s “hellish twin,” but it may be the last mission for a while. Other mission concepts are on the drawing boards, but no firm plans have yet been established.
The new findings were published in the Aug. 21, 2014, issue of the Journal of Physical Chemistry Letters.