Early Venus Could Have Sustained Liquid Water on Its Surface for Billions of Years That Made It Habitable, Study Suggests

Venus may be the brightest planet in the Solar System, but it is deeply inhospitable to life due to its toxic, scorching heat that humans can never tread.

But even so, Venus shares some strikingly similar characteristics with Earth. Both planets have almost the same size, mass, and density with very similar compositions, which raises the question of whether it was once habitable like Earth.

Early Venus Could Have Sustained Liquid Water on Its Surface for Billions of Years That Made It Habitable, Study Suggests

(Photo: Unsplash/NASA)
This picture of Venus was captured by the Mariner 10 spacecraft during its approach to the planet in early 1974

Habitable Conditions on Venus Did Not Last for Long

The new study, titled "Narrow Range of Early Habitable Venus Scenarios Permitted by Modeling of Oxygen Loss and Radiogenic Argon Degassing," published in PNAS, suggested that habitable conditions and surface liquid water on Venus would have only lasted briefly before the planet transformed into its parched state today.

The University of Chicago planetary scientists Alexandra Warren and Edwin Kite modeled the history of the atmosphere of Venus to know the rate and mechanisms at which it lost its oxygen, Science Alert reported.

Their model revealed that it was over 3 billion years ago when Venus had liquid water if it ever did so. If the model is right, Venus might have been more temperate and has lakes and oceans of liquid water.

Today, Venus is extremely dry and extremely low in oxygen. Its atmosphere comprises 96% carbon dioxide, 3% nitrogen, and some traces of sulfur dioxide. Venus' atmosphere is extremely thick, with pressure over 90 times Earth's, but ruined by powerful winds and sulfuric acid rain.

But due to its thick atmosphere, heat cannot escape Venus, making it the brightest planet in the Solar System because it also has the hottest surface temperature at an average of 464 degrees Celsius (867 degrees Fahrenheit).

Scientists want to know how and why Venus got to where it is now because of its similarity to Earth, and understanding its history could help them determine how likely Earth is to follow the same path.

What Happened to Venus' Atmosphere?

The lack of oxygen in the atmosphere of Venus is a bit mysterious since its ancient water would have evaporated and mixed into it as the planet heated up, breaking into hydrogen and oxygen atoms via photodissociation. According to ChemEurope, this process happens when a chemical compound is broken down and is a chemical reaction triggered by sunlight.

Moreover, hydrogen would have also leaked into space, but oxygen should have remained in the atmosphere. As Science Alert reports, Warren and Kite investigated where the oxygen went through a model based on habitable Venus.

They said one possibility is that the oxygen became bound up in carbon emitted by volcanoes and formed carbon dioxide, although this sounds unlikely. Rather, a second proposal said that the oxygen could have only experienced either of two fates.

First, it leaked into space or became sequestered in oxidizable magma, like basalt, on the planet's surface. Calculations reveal that it was also the same time when oceans dried up.

But aside from that, they also tried determining how much water Venus once had. They found it less than 300 meters (984 feet) deep or less than 10% of Earth's average 3,688-meter ocean depth. Researchers say that future missions could confirm this by measuring the composition of Venus' surface.