Context: The discovery of phosphine in the atmosphere of Venus has triggered excitement as a possible sign of life on that planet.

What is the gas, what is its connection with life, and how significant is the discovery?

• Apart from being produced in industrial processes, phosphine, a colourless but smelly gas, is known to be made only by some species of bacteria that survive in the absence of oxygen.
• A team of scientists have reported traces of phosphine in a concentration of approximately 20 parts per billion, thousands to millions of times more than what could otherwise be expected.

So, is there life on Venus?

• Scientists have discovered the presence of a chemical which is known to be produced only through biological process, and not through any naturally occurring chemical process.
• 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.
• In any case, scientists have ruled out all those kinds of known possibilities which could be attributed for the presence of that gas.
• Scientists were very careful to emphasise, repeatedly, that this was not a confirmation of the presence of life on Venus.

Why is it significant then?

• This is the most credible evidence yet for the possibility of life away from Earth.
• “In the search for extra-terrestrial life, this is the biggest finding, no doubt.

But Venus cannot support life, can it?

• The temperature of Venus is too high, and its atmosphere is highly acidic, just two of the things that would make life impossible.
• This phosphine could be remnants from a time when Venus was a much more hospitable place.

What can this mean for Venus missions?

• The finding can further ignite interest in space missions to Venus.
• Indian Space Research Organisation (ISRO) is also planning a mission to Venus, tentatively called Shukrayaan, in the near future. As of now, the plan is still on the drawing board.
• All future missions to Venus would now be attuned to investigating further evidence of the presence of life.

https://indianexpress.com/article/explained/reading-life-signature-on-venus-phosphine-gas-6596355/

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