Discovery of gas phosphine on planet Venus, a sign of life?

Looks like the next space exploration missions should be flying to Earth's twin, Venus, for more probing as news of the discovery of gas phosphine surfaced recently, hinting at possible life on the planet.

Could there be life on Venus? / Source: NASA/JPL-Caltech

In an article titled "Phosphine gas in the cloud decks of Venus," which was published on September 14, 2020, Nature Astronomy reported the presence of phosphine gas or PH3 in the atmosphere of Venus.

“The presence of PH3 is unexplained after exhaustive study of steady-state chemistry and photochemical pathways, with no currently known abiotic production routes in Venus's atmosphere, clouds, surface and subsurface, or from lightning, volcanic or meteoritic delivery.

“If no known chemical process can explain PH3 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.”

Phosphine was first obtained in 1783 by Philippe Gengembre through heating phosphorus in an aqueous solution of potash (potassium carbonate).

In its purest form, phosphine is colorless and odorless.

But in its technical grade form, it reportedly has odor reminiscent of dead fish or garlic.

Phosphine is highly flammable and very toxic by inhalation even at extremely low concentrations.

Ironically, it is often used as an insecticide and considered as a hazardous air pollutant.

On planet Earth, phosphine gas is also present in the atmosphere at very low and highly variable concentrations.

It is said to originate from the reduction of phosphate in decaying organic matter.

In 2019, the Massachusetts Institute of Technology (MIT) reported that phosphine is actually produced by anaerobic organisms like bacteria and microbes, which do not need oxygen to survive.

This is why many speculate that the presence of phosphine on Venus could signal that there is actually life on the planet.

However, Nature Astronomy strongly underlined that the discovery of phosphine on Venus is not enough evidence to confirm that there is life on Earth's twin planet.

“Even if confirmed, we emphasize that the detection of PH3 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.

“To further discriminate between unknown photochemical and/or geological processes as the source of Venusian PH3, 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.”

The National Aeronautics and Space Administration (NASA) has also issued an official statement regarding the stunning discovery.

“A paper about chemistry on Venus was published today in Nature Astronomy. NASA was not involved in the research and cannot comment directly on the findings; however, we trust in the scientific peer review process and look forward to the robust discussion that will follow its publication.”

It is not the first time that traces of phosphine had been found in the atmosphere of a planet other than Earth.

In the 1970s, phosphine was also detected in the atmospheres of Jupiter and Saturn, two planets deemed as hot gas giants.

Whether or not phosphine is a biosignature or sign of life on planet Venus or other planets, is something that only further space exploration and studies will confirm or debunk in the future.