Clouds on Venus could answer many mysteries of shrouded planet

18 Jul 2016

Venus remains one of the least mapped planets in our solar system despite it being our other closest neighbour, but new analysis of its thick clouds might give us answers to what lies beneath.

We’ve mapped Mars in incredible detail and begun the early stages of mapping the surface of Pluto, yet our other nearest neighbour, Venus, remains one of our least understood planets in the solar system.

Despite the fact that Venus is nearly twice as close to our own planet than Mars, it hosts one of the most hostile environments in the solar system, resistant to all attempts by humans to send spacecraft to study it in detail.

Due to a greenhouse effect that can only be described as extreme, the planet’s surface temperature can reach as high as 450 degrees Celsius with an atmospheric pressure 92-times that of Earth, making sending probes there incredibly difficult.

So far, our only images of Venus’s surface come from Soviet probes, the best of which came from Venera 13, which touched down in 1982 and lasted only 127 minutes in the inhospitable environment.

Venus surface

Images from the Veenra 13 lander via Soviet Planetary Exploration Program, NSSDC/NASA

‘Fountain of Aphrodite’

But now, observations from the former Venus Express satellite operated by the European Space Agency (ESA) are testing the theory that monitoring the planet’s weather patterns could help us create a picture of the surface below.

Venus’s cloud layer is around 20km-thick sitting between 50 and 70 km above the planet’s surface making it far colder than the boiling surface below, typically around -70 degrees Celsius. Not only is it colder, but this upper layer of clouds has winds which blow hundreds of times stronger than that of the surface and are so rapid that they spin faster than the planet actually rotates. This was most recently seen when NASA discovered a very powerful ‘electric wind’ on Venus that strips the planet of any moisture or atmosphere.

Using the Venus Express data on weather patterns on Venus, we can now form a better picture of what the planet’s topography looks like taking in three factors: how quickly winds on Venus circulate, how much water is locked up within the clouds, and how bright these clouds are across the ultraviolet spectrum.

Venus fountain

A diagram of the ‘fountain of Aphrodite’. Image via ESA

One potential discovery made using this method came from the new study’s lead author, Jean-Loup Bertaux of LATMOS (Laboratoire Atmosphères, Milieux, Observations Spatiales).

Bertaux located one area of cloud near the planet’s equator that contained considerably more water than neighbouring regions – largely thanks to a 4,500m mountain range called Aphrodite Terra – which has now been dubbed the ‘fountain of Aphrodite’.

A major result

Further analysis found the winds above the mountainous Aphrodite Terra region to be 18pc slower than in surrounding regions, but that they re-accelerate to normal speeds downstream of the range. This acts like an air pump, forcing the water-rich air upwards and creating the fountain-like effect.

“This certainly challenges our current general circulation models,” said Håkan Svedhem, ESA’s project scientist for Venus Express. “While our models do acknowledge a connection between topography and climate, they don’t usually produce persistent weather patterns connected to topographical surface features. This is the first time that this connection has been shown clearly on Venus – it’s a major result.”

Venus image via Shutterstock

Colm Gorey was a senior journalist with Silicon Republic