Key molecule discovered in Venus's ...( Venus Express has detected the molec...)

Venus Express has detected the molecule hydroxyl on another planet for the first time. This detection gives scientists an important new tool to unlock the workings of Venuss dense atmosphere.

Hydroxyl, an important but difficult-to-detect molecule, is made up of a hydrogen and oxygen atom each. It has been found in the upper reaches of the Venusian atmosphere, some 100 km above the surface, by Venus Expresss Visible and Infrared Thermal Imaging Spectrometer, VIRTIS.

The elusive molecule was detected by turning the spacecraft away from the planet and looking along the faintly visible layer of atmosphere surrounding the planets disc. The instrument detected the hydroxyl molecules by measuring the amount of infrared light that they give off.

The band of atmosphere in which the glowing hydroxyl molecules are located is very narrow; it is only about 10 km wide. By looking at the limb of the planet, Venus Express looked along this faint atmospheric layer, increasing the signal strength by about 50.

Hydroxyl is thought to be important for any planets atmosphere because it is highly reactive. On Earth it has a key role in purging pollutants from the atmosphere and is thought to help stabilise the carbon dioxide in the martian atmosphere, preventing it from converting to carbon monoxide. On Mars it is also thought to play a vital role in sterilising the soil, making the top layers hostile to microbial life.

The reactive molecule has been seen around comets, but the method of production there is thought to be completely different from the way it forms in planetary atmospheres.

Because the venusian atmosphere had not been studied extensively before Venus Express arrived on the scene, we have not been able to confirm much of what our models tell us by observing what is actually happening. This detection will help us refine our models and learn much more, says one of the Principal Investigators of the VIRTIS experi
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