Subscribe to our free daily newsletters
. 24/7 Space News .

Subscribe to our free daily newsletters

The Venusian Climate And Its Evolution

These images of the surface of Venus were taken by the Soviet Venera 13 lander in 1982. Credits: Venera 13/Russian Academy of Science
by Staff Writers
Paris, France (ESA) Dec 04, 2007
Today, Venus is a hellish place of high temperatures and crushing air pressure. Venus Express is showing that this was not always the case. Instead, some time in the past, Venus was probably much more Earth-like and contained large quantities of water. Planetary scientists have long wondered just how Earth-like Venus is or might have been. Until the 1960s, astronomers speculated that Venus might be a tropical forest planet. This view changed when microwave observations began to suggest an extremely hot surface.

The Russian and American spacecraft of the 1960s and 70s confirmed that Venus possesses surface temperatures of over 400C and surface pressure a hundred times that of Earth.

The winds in Venus's atmosphere are severe, blowing at speeds of up to, and over, a 100 m/s. Yet, as fierce as they are, not even the winds from the giant south polar vortex extend all the way down to the planet's surface.

Venus Express can see down to about 45-50 km above the surface in the south polar region. Feeding this data into computer models suggests that the vortex cannot penetrate into the lower atmosphere because of the great density of gas there. "It is difficult to move around such a heavy mass of atmosphere. We do not expect big winds at the surface of Venus," says Giuseppe Piccioni, IASF-Istituto Nazionale di Astrofisica, Italy.

How did Venus turn out like this?

Geologists say that the present is a clue to the past and the same is true for atmospheric physics. Venus Express has revealed an atmospheric process that points to a catastrophic event in Venus's history.

"Venus has suffered a radical climate disaster but we don't yet know how, why and when," says David Grinspoon, a Venus Express interdisciplinary scientist from the Denver Museum of Nature and Science, Colorado, USA.

The disaster was the loss of Venus's water. If you could condense all of the water vapour in Venus's atmosphere, it would create a thin covering of water just 3-cm thick. For comparison, if Earth were a smooth ball, all of the water in the oceans and atmosphere would create a covering 3-km deep.

Venus may once have had this much water as well but it has been gradually stripped off into space by the collision of energetic particles from the Sun. Today, Venus Express has shown that the last remnants of the process are still taking place with the escape of hydrogen and oxygen from the top of the atmosphere.

"We now know that Venus was once more Earth-like," says Grinspoon, "We cannot tell the full story yet, but the data we are getting shows that Venus Express will reveal the history of water on Venus.

Venus has no seasons because its rotation axis is already perpendicular to its orbit. It rotates just once in 243 Earth days and has a very massive atmosphere. This is chiefly composed of carbon dioxide with clouds primarily of sulphuric acid droplets.

It sounds nothing like Earth, and yet, thanks to Venus Express, planetary scientists now know that it can be explained in the same framework, but with Venus being driven in a different direction.

"The three most important parameters that determine a planet's 'behaviour' are its distance from the Sun, its surface pressure and its rotation rate," says Fred Taylor, a Venus Express interdisciplinary scientist from the University of Oxford, UK. So, although Venus is similar in size to Earth, it is drastically different in the three parameters that drive its behaviour.

There is another large unknown in the evolution of the atmosphere: the amount of lightning on the planet. Lightning drives the chemistry of an atmosphere by breaking molecules into fragments that can then join other fragments in unexpected ways. Nitric oxide formed in this manner is present in sufficient quantities to be detected from Earth.

"There may be as much lightning on Venus as there is on Earth," says Chris Russell at the University of California at Los Angeles, who was part of the magnetometer team that searched for, and found, lightning on Venus.

Throughout its extended mission, Venus Express will continue collecting vital data to better understand the evolution of this fascinating planet.

Email This Article
Comment On This Article

Related Links
Looking at Venus
Venus Express News and Venusian Science

Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News

Caught In The Wind From The Sun
Paris, France (ESA) Dec 03, 2007
Venus Express has exposed the true extent to which the Sun strips away the atmosphere of Venus. This process could be an important contribution to the way the planet has evolved to become so different from the Earth. The Sun has probably been stripping away the Venus' atmosphere throughout the planet's four-thousand million-year history.

  • MU Engineers Develop Software Solution For Complex Space Missions
  • Star Talk
  • Computer predicts Voyager 2 milestone
  • Computer Simulation Predicts Voyager 2 Will Reach Major Milestone In Late 2007¿Early 2008

  • Multi-Tasking Rover Supports Multiple Missions
  • Spirit Breaks Free In Race For Survival
  • Noctis Labyrinthus, Labyrinth Of The Night
  • Russia Conducts First Experiment In Preparation For Mars-500

  • Arianespace warns US over Chinese space 'dumping'
  • Sea Launch Reschedules The Thuraya-3 Launch Campaign
  • Sea Launch Reschedules The Thuraya-3 Launch Campaign
  • Russia To Launch Manned Spacecraft From New Site In 2018

  • China, Brazil give Africa free satellite land images
  • Ministerial Summit On Global Earth Observation System Of Systems
  • NASA-Conceived Map Of Antarctica Lays Ground For New Discoveries
  • Northrop Grumman-Built Hyperion Imager Celebrates Seventh Anniversary On-Orbit

  • The PI's Perspective: Autumn 2007: Onward to the Kuiper Belt
  • Data For The Next Generations
  • Goddard Instrument Makes Cover Of Science
  • Checking Out New Horizons

  • Dark Matter In Newborn Universe Doused Earliest Stars
  • An X-Ray Santa Claus In Orion
  • Dark Energy -- 10 Years On
  • Scientists Solve Cosmological Puzzle

  • Data From Chinese Lunar Orbiter Available To All
  • Northrop Grumman Starts Integration And Test On LCROSS Spacecraft
  • KAGUYA (SELENE) Composes 3-D Movies With Terrain Camera Images
  • China Publishes First Moon Picture

  • EU rallies Spain to clinch unanimous Galileo deal
  • EU nations 'close' to political agreement on satnav project
  • The Hills And Valleys Of Earth's Largest Salt Flat
  • US plans GPS satellite navigation upgrade to rival EU

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2007 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement