Acidic clouds of Venus

News:

Scientists have detected in the harshly acidic clouds of Venus a gas called phosphine that indicates microbes may inhabit Earth’s inhospitable neighbour, a sign of potential life beyond Earth.

The Acid Test:

• Some scientists have suspected that the Venusian high clouds, with mild temperatures around 86 degrees Fahrenheit (30 degrees Celsius), could harbor aerial microbes that could endure extreme acidity. These clouds are around 90% sulphuric acid. Earth microbes could not survive that acidity.
• On Earth, microorganisms in “anaerobic” environments – ecosystems that do not rely on oxygen – produce phosphine. 
• These include sewage plants, swamps, rice fields, marshlands, lake sediments and the excrements and intestinal tracts of many animals. Phosphine also arises non-biologically in certain industrial settings.
• To produce phosphine, Earth bacteria take up phosphate from minerals or biological material and add hydrogen.
• Venus should be hostile to phosphine. Its surface and atmosphere are rich in oxygen compounds that would rapidly react with and destroy phosphine.

Phosphine:

• Phosphine – a phosphorus atom with three hydrogen atoms attached – is highly toxic to people.
• It is known to be produced only through a biological process, and not through any naturally occurring chemical process.
• Phosphine was seen at 20 parts-per-billion in the Venusian atmosphere, a trace concentration.
• Researchers examined potential non-biological sources such as volcanism, meteorites, lightning and various types of chemical reactions, but none appeared viable.
• There are some other ways in which this chemical might be produced, for example, in the underbelly of volcanoes or meteorite activity, but that would have shown in much lower concentrations.