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Impact by finding that could indicate the presence of microbial life on Venus

publicado a la‎(s)‎ 28 oct 2020 10:47 por Plataforma Sites Dgac
On Monday, September 14, 2020, the world was surprised by the announcement by a group of scientists about the apparent presence of a gas in the clouds of Venus that could indicate of the presence of microbial life.
Scientists announced the find of phosphine gas in the clouds of Venus, which could be generated by geochemical processes yet unknown or by the presence of microbial life.

Rodrigo Herrera Camus, 
an academic at the University of Concepción, researcher at the CATA Astrophysics Center and Ph.D. in Astronomy from the University of Maryland.
Jane Greaves, an astronomer at the Institute of Astronomy at the University of Cardiff, in the United Kingdom, led the team responsible for the discovery and together with Anita Richards, from the University of Manchester; and William Bains and Sara Seager, both from the Massachusetts Institute of Technology (MIT), she announced during a videoconference that they detected the presence of phosphine in clouds at about 50 km above the surface of Venus that could be an indicator of the presence of life.

At the same time the announcement took place, the journal Nature Astronomy published an article about the find. 

Unlikely candidate 

The surface of Venus is a kind of rocky desert hell with temperatures close to 400 degrees Celsius and an atmospheric pressure of more than 90 times that which exists at sea level on Earth.             

However, about 50 kilometers above the surface of Venus the temperature reaches about 25 degrees Celsius and there is an atmospheric pressure similar to that of Earth. It is there that the phosphine that was first detected in June 2017 with the James Clerk Maxwell telescope in Hawaii is located. 

Although the data collected with the Hawaii telescope was inconclusive, in 2019 the Atacama Large Millimiter/submillimeter Array (ALMA), at the Atacama Desert in Chile, perceived a definitive phosphine signal. 

The atmosphere of our planet contains one part of phosphine in 10 trillion. On Venus, on the other hand, between five and 20 parts per 1,000 million were seen, according to Clara Sousa-Silva, an astronomer at MIT and co-author of the study. According to her analysis, this concentrations may be due to the presence of unknown geochemical phenomena or the presence of life.

Toxic gas 

Phosphine —or phosphane— is a toxic gas that smells like garlic and rotten fish and kills life forms that depend on oxygen. Phosphine was used as a chemical weapon during World War I, it is still used for agricultural fumigations, as rat poison, in the semiconductor industry and it is also generated from the manufacture of methamphetamines.

However, phosphine is also a natural product of some species of anaerobic bacteria, which are organisms that live in environments devoid of oxygen, such as landfills, swamps, and animal intestines. 

The phosphine molecule (PH3) has a pyramidal structure. Above is a phosphorous atom and below, three hydrogen atoms. 

“Although phosphine gas has been detected on Jupiter and Saturn, these are planets that have the conditions in their atmosphere, as they are giant planets, to be able to create phosphine without the need or the intervention of microorganisms, as it happens here on Earth”, explains Rodrigo Herrera Camus, an academic at the University of Concepción, researcher at the CATA Astrophysics Center and Ph.D. in Astronomy from the University of Maryland. 

“Now, Venus is a planet similar to Earth. Then, the fact that we detect phosphine gas, and the abundance in which it was detected, which is greater than the abundance that exists on Earth, would indicate that if there is no geological or physical-chemical process in the atmosphere that can produce it, this phosphine may be, in some way, linked to the presence of microorganisms that generated it”, added the specialist. 

In 2019, the scientific team that made the announcement published a study that concluded that the presence of phosphine in any rocky planet with warm temperatures is a biomarker that has no false positives. Therefore, the hypotheses being considered now is that, in effect, the phosphine captured on Venus is due to geochemical processes hitherto unknown on that planet or to the presence of microbial life. 

Scientific enigma 

In simple words, phosphine should not be present in the Venusian atmosphere. According to scientists, it is very difficult to process and the chemistry in clouds of sulfuric acid covering Venus should destroy these molecules before they can accumulate to the observed quantities. 

However, the scientists caution that even the very detection of phosphine must be verified and that the footprint of that gas described in the study could be a false signal generated by telescopes or data processing. 

The possibility of life in the clouds of Venus is also not new, but has been considered for almost 60 years. 

“While the surface conditions on Venus make the hypothesis of life there implausible, the clouds of Venus are a different story altogether”, wrote the renowned astronomer Carl Sagan and his colleague Harold Morowitz in the journal Nature in 1967. 

According to César Fuentes, Ph.D. in Astrophysics from Harvard University and an academic at the School of Physical Sciences and Mathematics of the University of Chile, the discovery “puts Venus higher on the list of priorities to search for life in the Solar System”. 

According to Dr. Herrera, the next steps are to study the characteristics of Venus more carefully. 

“The first important step is to improve the current model we have of the atmosphere of Venus to really be able to rule out that there is a process in its atmosphere, whether due to radiation from the Sun, geological, etc., that can produce phosphine without the need to invoke microorganisms that produce it”, he said. 

“And of course it would be great if we could have probes that would visit the planet Venus. There are a couple of private initiatives, India also has a project in mind and in February NASA announced among its finalists some projects that could visit the planet Venus”, he said. 

“So while this finding of phosphine gas does not directly indicate that life exists on Venus, it increases our chances that our neighbor can actually harbor microorganisms and, of course, fuels interest in trying to finance missions that visit this planet in the short term”, concluded the astronomer.

Sources: Nature Astronomy, Las Últimas Noticias, Space.com and El País.
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