Scientists from UK recently detected traces of gas, known as Phosphine, in the clouds of planet Venus.
They believe that it could be an indication that the planet supports microbial life.
The gas phosphine occurs on planet Earth as a colourless gas that smells like garlic, or decaying fish. The gas is naturally produced in the absence of oxygen, mainly by certain microorganisms, and can also be released in small amounts from the breakdown of organic matter.
Venus is known to be inhospitable due to its surface temperature, which is around 464°C, and its pressure, which is 92 times that of on the Earth. However, scientists revealed that its upper cloud deck is 53–62 kilometres above the surface and reaches a temperate of 50°C, with a pressure equal to that at Earth sea level.
Venus's clouds are also highly acidic, which means that the phosphine would be broken down very quickly.
NASA is presently considering two missions to Venus. They will propose to study the planet's atmosphere and geochemistry, and will be named the 'DAVINCI' and 'VERITAS' missions.
The James Clerk Maxwell Telescope at Hawaii's Mauna Kea Observatory, and the Atacama Large Millimeter/submillimeter Array in Chile, was used in the study by astronomer, Jane Greaves of Wales' Cardiff University, and colleagues to observe Venus.
When they detected the sign of the gas, they were able to estimate that the gas is present in Venus' clouds in an abundance of around 20 parts-per-billion.
The team have explored various ways that the gas could have been produced in this setting. One of the ways included sources on the surface of the planet, micrometeorites, lightning, or chemical processes happening within the clouds themselves.
The team was unable to determine what the source of the detected trace quantities of the gas are.
The researchers have cautioned that this only indicates that potentially unknown geological or chemical processes are occurring on the planet, and that further observations and modelling will be needed.
The report of the study stated that; "Phosphine could originate from unknown photochemistry or geochemistry – or, by analogy with biological production of phosphine on Earth, from the presence of life. If no known chemical process can explain phosphine within the upper atmosphere of Venus, then it must be produced by a process not previously considered plausible for Venusian conditions.
"This could be unknown photochemistry or geochemistry – or possibly life. Even if confirmed, we emphasise that the detection of phosphine is not robust evidence for life, only for anomalous and unexplained chemistry.
"There are substantial conceptual problems for the idea of life in Venus's clouds – the environment is extremely dehydrating as well as hyperacidic. However, we have ruled out many chemical routes to phosphine, with the most likely ones falling short by four to eight orders of magnitude. To further discriminate between unknown photochemical and/or geological processes as the source of Venusian phosphine, or to determine whether there is life in the clouds of Venus, substantial modelling and experimentation will be important. Ultimately, a solution could come from revisiting Venus for in situ measurements or aerosol return."
Greaves added that; "The only successful Lander that sent back Venus data was Vega 2, in 1985. Let's hope now that space agencies will want to go back."
The full findings of the study were published in the Journal Nature Astronomy.