By Samriddhi Mishra
The search for extraterrestrial life started all the way back in 1950 with the fermi paradox. The question ‘Where are they?, famously asked by Enrico Fermi as a casual lunchtime remark, has been puzzling researchers fordecades and now, with the emergence of organizations such as SETI, the search for extraterrestrial life is stronger than ever.
In September 2020, a research team led by Jane Greaves of Cardiff University claimed to have found spectral traces of phosphine in Venus’s atmosphere and since then it has been all over the news. So how is phosphine related to extraterrestrial life? What is fact and what is fiction?
Let’s find out!
Phosphine is a rare gas consisting of Hydrogen and Phosphorus (formula PH₃) that can only be made industrially or by certain anaerobic (Oxygen-free) bacteria on Earth. The traces of this gas, according to Professor Greaves’s study, were found by examining the spectra (electromagnetic emission) of Venus’s atmosphere using data sets from the James Clerk Maxwell Telescope (JCMT) in Hawaii and the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile.
If the study proves to be accurate,, this could be the greatest breakthrough in the search for extraterrestrial life till date!
Using the data sets from the telescopes, the researchers found that the phosphine on Venus is present in only about 20 molecules in every billion. They then studied the photochemical processes on Venus to determine the gas’s source. Unfortunately, the existing information is highly inadequate as the only other experiment regarding phosphorus on Venus was performed by the Soviet Vega 2 probe in 1985.
So what are the natural ways that phosphine can be manufactured on Venus?
The researchers considered the following processes: minerals blown upwards from the surface, volcanoes, sunlight, and even lightning, but these can be eliminated. As the total amount of phosphine these processes could produce is still one ten-thousandth of the amount of phosphine that the telescopes observed..
This discovery could be revolutionary as Co Author Dr. Clara Sousa Silva from MIT is also considering searching for phosphine as a biosignature of extraterrestrial life that thrives on elements and substances other than Oxygen (a similar situation can be seen on Saturn’s moon Titan where there’s a chance of organisms existing on methane and ethane cycles instead of the oxygen, carbon and nitrogen cycles that we’re familiar with).
Interestingly, there might be another sign of life on Venus, as the dark streaks obtained in the spectrum of Venusian atmosphere, where ultraviolet light is absorbed, could come from colonies of microbes! The Japanese Space Agency (JAXA) has also launched the Akatsuki spacecraft for better understanding of this possibility.
Greaves’s team now hopes to gather more information from the telescopes to confirm if the phosphine comes from a relatively temperate part of the Venusian atmosphere, so that they could look for other potential gases that could indicate life. With this discovery, potential new space missions, travelling to our neighboring planet to search for other signs of life becomes far more likely.
Astronomers all over the world have speculated the existence of floating microbes on Venus for years, and it’s comforting to know that the lifelong dream might finally come true.
However, there are some complications with this idea, as there have been many controversies and criticisms regarding this study. So, we can’t be sure just yet. However, phosphine on Venus has successfully opened a brand new door for the search for life on other planets.
Previously, the viable candidates in our solar system for harboring life were considered to be the moons, Europa and Enceladus with liquid water oceans under their ice. No one actually thought that microbes could exist in the extreme acidic atmosphere of Venus, but this assumption could be proven wrong!
The important thing to know is that even if the phosphine isn't necessarily because of extraterrestrial life, it has been found on Venus, which means that there may be some processes occurring there that we don’t know about.
Hence, this discovery can lead to an update in our existing scientific knowledge, and improvements to our knowledge of the universe is what science is all about!!
Jane S. Greaves et al. ‘Phosphine Gas in the Cloud Decks of Venus.’ Nature Astronomy (2020). https://www.nature.com/articles/s41550-020-1174-4