'Electric wind' sucked water away from Venus, scientists say

An artist's concept of the electric wind at Venus. Rays represent the paths that oxygen and hydrogen ions take as they are pulled out of the upper atmosphere. (NASA/Goddard/Conceptual Image Lab, Krystofer Kim)

We already know there isn’t any water on Venus, but scientists working with ESA’s (European Space Agency) Venus Express mission by NASA-funded researchers think they may have solved the mystery of how the planet’s oceans ultimately disappeared: they were sucked away by a powerful electric wind.

In a report filed on Monday, NASA wrote on its website, the team discovered the planet’s electric field while they monitored electrons as they flowed out of Venus’ upper atmosphere using the electron spectrometer, a component of the ASPERA-4 instrument, aboard the ESA Venus Express. They found the electrons were not escaping at the speeds that were expected. Scientists said the speed was influenced by Venus’ electric field, which is thought to be at least five times more powerful than Earth’s.

Every planet has a gravity field, and scientists believe that every planet with an atmosphere is surrounded by a weak electric field. These two are at odds with one another as gravity strives to hold the atmosphere together and the electric field can push upper layers of an atmosphere into space, according to the report.

In the case of Venus, hydrogen moves fast and escapes easily, and the planet’s strong electric field “can accelerate even the heavier electrically charged component of water — oxygen ions — to speeds fast enough to escape the planet’s gravity.”

Sunlight then breaks the water down in the upper atmosphere and the components are whisked away by the electric field.

Glyn Collinson, a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said the discovery points to electric wind as, “this big monster that’s capable of sucking the water from Venus by itself.”

“We don’t really know why it is so much stronger at Venus than Earth,” said Collinson, “but, we think it might have something to do with Venus being closer to the sun, and the ultraviolet sunlight being twice as bright. It’s a challenging thing to measure and even at Earth to date all we have are upper limits on how strong it might be.”

Although Venus is often referred to as “Earth’s twin,” for being similar in size and gravitational pull, Venus has drastic differences. The planet has surface temperatures of around 860 degrees and a thick atmosphere with about 100 times the pressure of Earth’s.

Scientists are taking this information and applying it to hunt for potential electric wind on Mars as part of the MAVEN mission.

“Even a weak electric wind could still play a role in water and atmospheric loss at any planet,” said Alex Glocer of NASA Goddard, a co-author on the paper. “It could act like a conveyor belt, moving ions higher in the ionosphere where other effects from the solar wind could carry them away.”