On Sept. 14, a team of astronomers led by Cardiff University’s Dr. Jane Greaves reported the presence of possible signs of life in the clouds of Venus in two papers published in the Nature Astronomy Journal. Using two very powerful telescopes, the scientists have detected the presence of the chemical gas Phosphine in Venus’ atmosphere. On Earth, this gas, consisting of an atom of Phosphorus bonded to three hydrogens, is only produced by human activities and by microbes living in oxygen-free environments.

To make the discovery, scientists used a technique called absorption spectroscopy, specifically using millimeter-wavelength radio waves. “Using a fancy prism, you can break up light [passing through a certain material] into very fine wavelength bands. Embedded in the information of how much light can be seen at each wavelength is the information of what the material is composed of,” explained Ian Dobbs-Dixon, Associate Professor of Physics at NYU Abu Dhabi and a member of the NYUAD Center for Space Science and the NYUAD Center for Astro, Particle and Planetary Physics. Every gas has a unique spectral signature, which allows for its detection even by indirect observation of the light coming from that atmosphere.

The presence of Phosphine is a strong indicator for the possibility of life on Venus as “based on our understanding of Venus, there is no physical or chemical process which could produce Phosphine, so biology is the prime suspect,” shared Dr. Dimitra Atri, a research scientist at the NYUAD Centre for Space Science.

Often called Earth’s twin, Venus and Earth are physically very similar. But its thick atmosphere, which exerts a pressure equivalent to being 3,000 feet under sea level, clouds of sulfuric acid and surface temperatures over 800 °F lead to an environment that is hot and hellish. This presents a stark contrast to the temperate and water-filled Earth.

Dobbs-Dixon also stated that these extreme conditions on Venus also makes exploration difficult, as any probes sent to the planet’s surface only work for around an hour before they stop functioning due to the extreme heat.

While the possibility of life on another planet is exciting, the theory faces some challenges. Dr. Atri elaborated, “I note two major issues: (1) The atmospheric chemistry of Venus is not well understood because of a lack of measurements and good observations. There could be a non-biological process in its atmosphere which is producing Phosphine, but we might not know until we learn more about its atmosphere. (2) We don't really understand how biology produces Phosphine. Although we know that biology produces Phosphine, the exact biochemical pathway is not known.”

The authors of the original papers are working to further prove that the signal is indeed that of Phosphine and not a false positive. They had planned observations using the Stratospheric Observatory for Infrared Astronomy and NASA’s Infrared Telescope Facility in Hawaii, which will help detect the multiple fingerprints of Phosphine across a range of the Electromagnetic Spectrum. However, the team’s efforts have currently been put on hold due to the Covid-19 pandemic.

Further studies and missions to Venus will be required to conclusively prove the existence of life on Venus. The European Space Agency has already said that they will be on the lookout for traces of Phosphine when their BepiColombo probe flies past Venus. Possible future missions such as Venus orbiters or atmospheric probes attached to balloons will help collect more data to help us analyze whether life exists on Venus.

If this discovery is verified, it increases the hopes for detecting life on other worlds as well, including Mars, Jupiter’s moon Europa, and Saturn’s moon Enceladus. As Dr. Atri explained, “If microbial life is found anywhere other than the Earth, it would indicate the widespread nature of life.”