Signs of Life on Venus

November 2021 AAA Lecture. Report by Monica Prado Capon, a Brooklyn College undergraduate studying astronomy with AAA's David Kiefer.

One of the biggest questions that humanity is still trying to solve is; are we alone in the universe? Given the urge of wanting answers, we started to search for signs of life on other planets, and here we are today talking about possible life on Venus.

The speaker of the month was Dr. Sara Seager, a professor of physics and planetary science at MIT. She has a research interest in a theoretical model of exoplanets atmosphere and interiors, and that led to the first detection of exoplanets atmospheres. Dr. Seager is also part of the team that discovered the first detection of exoplanet light and the first spectrum of an exoplanet. Additionally, Dr. Seager has an active interest, and takes part in the research of Earth life, planets and signs of life on them, she has been perusing the explanation of Venus as a habiting world.

The lecture began by raising and explaining some basic ideas as photosynthesis and oxygen. Dr. Seager explains that one of the main signs astronomers used to look for when searching for life on other planets is oxygen, as they call it biosignature gas. However, Dr. Seager started the discussion by saying that maybe is not going to be oxygen. Our planet, for example, did not contain oxygen until bacteria figured out how to produce it, taking ages to accumulate high amounts.

One of her research themes asks: what type of gases can produce life in another world? Specifically, which type of gasses should be considered so as not to miss a sign of alien life. Having said that, Dr. Seager mentions that one type of gas came to their attention: phosphine. Phosphine contains one phosphorus atom and three hydrogen atoms. There is evidence that phosphine is made by life on earth and can be found in oxygen free environments.

With her team, Dr. Seager works with phosphine as a biosignature gas on exoplanets for future telescopes to be considered, with the knowledge that Venus would be a terrible planet to look for life. The high temperatures of Venus make the surface incredibly difficult for any kind of life to survive, also, it is too bright for large telescopes and other facilities to point at it. After these facts, Dr. Seager introduced an interesting point: while there is no life on the Venusian surface, the clouds are cold enough to support life; the higher into the Venusian atmosphere you go, the colder it gets, same as here on Earth, about 50 km above the surface of Venus, would be the right temperature for life.

Venus has permanent clouds that cover the planet completely and are 20 km deep. If there is possible life in the clouds of Venus, it probably has some type of shell. While the good news is that her team found signs of phosphine on Venus, they don’t claim that there is life, but they want to leave open the possibility of the phosphine meaning something. Dr. Seager concluded by explaining why Venus is such an interesting planet to investigate. An example given referred to NASA’s previous missions to Venus, finding multiple anomalies – like oxygen – in the atmosphere. She explained how that inspired her to do a similar mission, but within the clouds. She and her team are in the planning stages so far, with two plans for it.

All things considered; the talk was intriguing and engaging. I especially found it fascinating how they were committed to thinking outside of the box. Instead of looking for planets with a surface that have a sustainable temperature for life, they look towards the clouds of an extremely warm planet which can’t host life on the surface.