Washington, September 16 (ANI): 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 vapor in the Venusian atmosphere at altitudes ranging from the lowest 10 km up to 110 km, high above the cloud tops.
Studies led by scientists from Belgium and Russia 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 vapor 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 away by the solar wind."
"These results from Venus Express demonstrate that the heavier water containing deuterium has not been able to escape Venus's gravity as easily as normal H2O. This enrichment of heavy water provides strong evidence that water loss is occurring in the upper atmosphere and that Venus was probably more humid and Earth-like in the distant past," he said.
Other studies by groups at the LESIA laboratory and the University of Oxford show that concentrations of water vapor decline from around 44 parts per million in the hot lower atmosphere to 25 parts per million at an altitude of 30-40 km.
At this level, the amounts of water vapor vary according to the overlying sulfuric acid cloud cover, with regions of thicker cloud containing less water vapor. (ANI)