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It is an extraordinary discovery and has a Portuguese signature. An international team of astronomers announced today that a rare molecule, phosphine, has been detected in the atmosphere of Venus, an indicator of the existence of life.
Scientists have been speculating for decades about the possibility of life in the high clouds of Venus. An environment that, despite its high acidity, has a pleasant 30ºC that could offer a home for microbes, far from the scorching surface of the planet. The discovery of phosphine may point to this “aerial” extraterrestrial life.
Clara Sousa Silva, a scientist at MIT, made an important contribution to the research, as phosphine is the molecule that she has been studying since her doctorate and will continue to study.
Clara Sousa Silva with a three-dimensional phosphine model
Melanie Gonick, MIT
Phosphine, a life marker
Phosphine or phosphine (PH3), composed of hydrogen and phosphorus, is a colorless gas, very toxic and with an “extremely smelly odor”, as Clara Sousa Silva explains in an article published in Scientific American magazine.
It is rare on Earth and toxic to organisms that live on oxygen, such as humans. But for anaerobic life, which lives without oxygen, in the swamps and intestines of most animals, phosphine is not a problem.
On Earth, this The gas is produced by these living organisms. They thrive in these oxygen-free environments and are also produced by industry.
What does phosphine mean in the atmosphere of Venus?
This gas is present in gaseous planets like Jupiter and Saturn, but here it does not mean the existence of life because phosphine is produced spontaneously in the atmospheres of these planets where the temperatures are very high and where there is a lot of hydrogen pressure.
But on terrestrial or telluric planets, such as Earth and Venus, which do not have these environments for phosphine to occur spontaneously, “phosphine can only be produced for life”, explains Clara Sousa Silva.
But can you already say “there is life on Venus”?
The Portuguese scientist explains that there are two doubts, noting that this study appears after a year and a half of in-depth research.
“Is it really phosphine or another exotic molecule that we don’t recognize?”.
Clara Sousa Silva reinforces that the sign of the existence of phosphine in the atmosphere of Venus “is quite strong and is the most plausible explanation.”
“The next step is to unambiguously confirm that what we detect on Venus is actually phosphine. More observations are needed, using other frequencies of light, observations in other areas of the Venus light spectrum, where phosphine is active.”
“If it is indeed phosphine, what does that mean?”
Venus used to be habitable, which is not to say that it was inhabited. Today, after an uncontrolled greenhouse effect, the planet has become truly hostile: it is extremely hot (462ºC on average), it has active volcanoes and an atmosphere made up mostly of carbon dioxide.
So for the existence of life, the surface does not, but there are parts of the atmosphere where this will be possible.
“As the surface became more uninhabitable, parts of the atmosphere were able to remain more or less comfortable. There is a layer, less and less thick, that theoretically remains habitable. And it was in this layer that we discovered phosphine. “
“IF it is phosphine and IF it is life, it means that life is much more common than we thought. If life can appear on Earth and on Venus, such different environments, then it means that life is inevitable and appear anywhere where it may appear. “
“This discovery may mean that if there are possibilities for life, then there is probably life” on any planet, concludes the Portuguese scientist who has devoted herself to the study of phosphine as a marker of life on exoplanets.
Clues to life on Venus from Earth
Venus is the hottest planet in our solar system, despite being the second closest to the Sun, it is the planet that has a denser atmosphere that retains heat, in a more violent greenhouse phenomenon than Earth.
This is one of the main reasons why it is so difficult to send instruments to study Venus. In the 1980s, several probes were sent, but they all melted as soon as they broke through the atmosphere.
The current observations by the international team of 15 scientists from the US, UK and Japan were made with the James Clerk Maxwell Telescope (JCMT), located in Hawaii, and then confirmed using the 45 antennas of the ALMA radio telescope. , Atacama Large Millimeter / Matriz submillimetrica, found in Chile.
The discovery was published today in the magazine Nature astronomy.
Planet Venus seen by the ALMA observatory, Atacama Large Millimeter / submillimeter Array
SO / NAOJ / NRAO
Venus will have already been like Earth and will have had life
Today, the second planet from the Sun is truly hostile: it is very hot (on average 462ºC), it has active volcanoes and an atmosphere composed mainly of carbon dioxide. But it won’t always have been that way, a 2016 study revealed.
Starting from the idea that Venus and Mars would have been similar billions of years ago, at a time when the Earth’s atmosphere was also composed mainly of carbon dioxide, scientists from NASA, Uppsala University, the Columbia University and the Institute of Planetary Sciences created four possible scenario simulations of what has happened to Venus since then.
According to the models used to study the evolution of the climate on Earth, the variables of each climate simulation of Venus were slightly modified, for example, the energy received from the Sun or the length of the days. They allowed the models to evolve for about two billion years.
One of the simulations resulted in a planet with temperatures low enough for life to exist that would have lasted until about 715 million years ago, when there was already life on Earth.
A close-up of the planet Venus in an animation made from data obtained with the James Clerk Maxwell telescope and the ALMA radio telescope.
