The American and British astronomers who published the recent article appeared on Nature Astronomy, regarding traces of phosphine on the atmosphere of Venus, they are causing a certain sensation, because this organic substance could be – according to some media that have relaunched the news – an indication of the presence of life. The substance was detected through several millimeter-band spectral telescopes. By means of spectroscopy it is in fact possible to detect traces of various substances that pass through electromagnetic radiation.
In February 2019, for example, traces of complex organic molecules around the star Orion. There is also an ESA project that foresees the launch of the space telescope by 2028 Ariel, with the purpose of mapping several esopianeti where the presence of primordial life forms is more likely.
Life on Venus?
Is it possible that instead of looking so far, life eventually lies on Venus and not on other candidates, such as Mars or the icy moons of Jupiter and Saturn, respectively. Europa ed Enceladus? As usual, caution is never too much. Detecting an apparent presence is not the same as ascertaining it; if we are dealing with organic substances, we must see if they actually led to forms of life.
But the possibility cannot be ruled out. It is true that the extremely dense atmosphere of Venus does not seem to us the height of hospitality, but that does not mean that it can be prohibitive for very simple life forms, such as bacteria. And actually phosphine is usually considered a rather strong trace of the presence of anthropogenic activity or microbial life.
“It has recently been proposed that any phosphine (PH3) detected in the atmosphere of a rocky planet is a promising sign of life – the researchers explain – The PH3 trace in the Earth’s atmosphere (parts per trillion of abundance globally) is associated in univocal way to anthropic activity or to microbial presence: life produces this highly reducing gas even in a general oxidizing environment ».
The limits of the study
If scientists rule out contaminations that may have biased their results – as explained in their study – why are they talking about an apparent presence of phosphine? There are actually limits. At the moment, astronomers cannot rule out other sources, such as photochemical or geological phenomena currently unknown.
«The information is lacking – continue the authors – for example, the photochemistry of the droplets of the Venusian clouds is almost completely unknown. A possible photochemical source must therefore be considered […] The questions as to why hypothetical organisms on Venus could produce PH3 are also highly speculative. ‘
Thus, the researchers hope for new studies and are keen to clarify that for the moment “even if confirmed, we underline that the detection of [fosfina] it is not robust evidence for life, but only for anomalous and inexplicable chemistry ».