Solar wind strips off water from Venus

Observations by the European Space Agency’s (ESA’s) Venus Express mission have provided strong new evidence that the solar wind has stripped away significant quantities of water from Earth’s twin planet Venus. The SPICAV and VIRTIS instruments carried by the spacecraft have been used to measure concentrations of water vapour in the Venusian atmosphere. Studies have found that the ratio of heavy water, which contains the isotope deuterium instead of hydrogen, to normal water is nearly twice as high above the clouds compared to its value in the lower atmosphere. According to Dr Emmanuel Marcq of the LATMOS laboratory in France, “Water vapour is a very rare species in the Venusian atmosphere: if it were in liquid form now, it would cover the surface of Venus with just a few centimeters of water. However, we believe Venus once had large volumes of water that have since escaped into space or stripped way by the solar wind.”