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NASA has reported that an “electric wind” can strip Earth-like planets of oceans and atmosphere. The statement came after it was found out that planet Venus has an electric wind that is strong enough to remove components of water from its upper atmosphere.
Researchers think that planets with atmospheres have electric fields that can pull molecules from the upper parts of the atmosphere out into space, overcoming the planet’s gravity, NASA said.
Data collected by the European Space Agency’s Venus Express spacecraft (detailed in the new study) shows that Venus’ electric field is particularly strong, and could be responsible for stripping away the planet’s water vapor.
“It’s amazing, shocking. This is something that has to be on the checklist when we go looking for habitable planets around other stars,” says Glyn Collinson, a scientist at NASA’s Goddard Space Flight Centre in Maryland, and lead author of a paper published in the journal Geophysical Research Letters.
Venus is in many ways similar to Earth. It is of similar size and gravity and once contained oceans of water.
Most of that water has boiled away, thanks to surface temperatures of around 460 °C. But the steam has also disappeared, probably after it split into its constituent hydrogen and oxygen.
Researchers believe the light hydrogen escaped, while the oxygen vanished into oxidised rocks, or was eroded from the upper atmosphere by the solar wind — a million-mile-per-hour stream of charged particles blowing from the sun.
The new research suggests a third phenomenon in play – the electric wind.
It is believed that every planet with an atmosphere is surrounded by a weak electric field that can push the upper layers of the atmosphere off into space.
“We found that the electric wind, which people thought was just one small cog in a big machine, is in fact this big monster that’s capable of sucking the water from Venus by itself,” Collinson says.
In the case of Venus, the electric field is so strong that it accelerated even the heavier electrically charged component of water — oxygen ions — to speeds fast enough to escape the planet’s gravity.
The scientists discovered Venus’ electric field using the electron spectrometer aboard the Venus Express.
They were monitoring electrons flowing out of the upper atmosphere when it was noticed that these electrons were escaping faster than anticipated – they were being dragged along by Venus’ electric field.
This field, they calculated, was stronger than expected – at least five times more powerful than at Earth.
“We don’t really know why it is so much stronger at Venus than Earth,” Collinson says, “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.”
Agencies/Canadajournal
