Venus Gasses Surrender Info to VIRTIS

The European Space Agency‘s Venus Express has recently ‘peeled back’ the thick clouds around Venus and has been able to provide the most accurate and wide-ranging map of water vapour and other gases in the lower atmosphere to date. As a planet, Venus does not radiate a significant amount of visible light. However, due to the searing temperatures below its thick cloud layer, reaching 200oC at an altitude of 35 km, and more than 450oC at the surface, there is great deal of infrared radiation coming from beneath. At certain wavelengths, or infrared ‘windows’, this radiation can pass through the thick clouds, carrying information on what lies below. For example, its intensity, and how it peaks or dips at certain wavelengths, can tell us a lot about the composition of the atmosphere.

Thanks to the unique ability of its VIRTIS spectrometer to use these spectral windows, Venus Express has mapped the atmosphere over many orbits and has covered the lower atmosphere for the first time. The atmosphere of Venus is dominated by carbon dioxide but, as VIRTIS looked on, it detected the signature of carbon monoxide, an unusual find in the planet’s deep atmosphere. Looking further, in higher resolution, scientists also found carbonyl sulphide and water vapour. Before Venus Express, such had never been measured and mapped so extensively and accurately. Carbon monoxide is such a rarity on Venus that it can be used as a tracer to monitor circulation patterns in the atmosphere. The existence and abundance of water vapour in Venus’s atmosphere has been a subject of debate for many years because the molecule is quite difficult to monitor in the lower atmosphere from space. Venus Express has now detected and measured and mapped the amount of water vapour in the lower atmosphere, with unprecedented spatial resolution.