Life on Venus? NUS experts give their insights
Could the gas clouds of Venus contain otherworldly life? Dr Ng and Dr Yang from NUS Physics weigh in on the debate.
A study published in Nature Astronomy on 14 September has claimed that there could be signs of life in the toxic atmosphere of Venus.
The astronomers making this claim have detected trace amounts of a chemical – phosphine – in the clouds of Venus, the source of which cannot be established. After much analysis, the scientists assert that something alive could be an explanation.
On Earth, phosphine is a gas exclusively associated with life and is not made by any other natural atmospheric or geological chemical process. The exact mechanism for its production is still unknown, but it forms in the presence of anaerobic (non-oxygen-breathing) bacteria, in low oxygen environments. As such, on Earth, the presence of phosphine is an indicator of the presence of life.
Here, Dr Cindy Ng and Dr Abel Yang from NUS Physics give their insights into the significance of the discovery of phosphine on Venus.
Q: Scientists have recently published results suggesting that there could be life on Venus. What are your thoughts on the finding?
Dr Ng: This is an interesting finding. It involved repeated observations and modelling with the consideration of plausible processes that could produce the phosphine. The researchers deduced that the phosphine could not be produced by a known process. Hence, they conclude that an unknown geological process or biological source produces the phosphine.
In the field of astronomy, it has been a long-standing speculation that life could exist in the cloud layers of Venus. This finding, if confirmed, will have profound implications for our understanding of life and its origin.
Dr Yang: However, I think it is premature to consider this as a sign of life. There is a lot we do not know about the atmosphere of Venus, such as the chemical reactions that would create phosphine, or even the source of phosphorous.
Q: Why are the clouds layers considered a possible habitat for life as opposed to the planet's surface?
Dr Yang: While the surface of Venus is too hot for life as we know it, at an altitude of about 50 kilometres, the atmospheric pressure and temperature is roughly similar to Earth. This is a reason why people have proposed floating colonies on Venus. However, this only covers the physical aspects of pressure and temperature, and does not cover the chemistry aspect.
Q: Have there been any past indicators of life on Venus?
Dr Ng: One past indicator of life on Venus was the discovery of an absorption of ultraviolet light in Venus’ atmosphere. It was also caused by an unknown process. Proposed processes included microorganisms as the absorbers.
Q: When it comes to space exploration, Venus seems to have been overlooked when compared to our other neighbour, Mars. Why is this?
Dr Ng: Mars has been the most interesting target of space exploration because it is the most habitable object in our solar system. Following the discovery of phosphine on Venus, the future space exploration missions may search for life on Venus instead.
Q: Compared to Mars exploration, what are some features that a spacecraft en route to Venus needs?
Dr Ng: Landers going to Venus must be resistant to the high temperature and pressure of Venus’ dense, carbon-dioxide atmosphere. Landers could be equipped with a cooler. Spacecrafts could be used to explore Venus from a high altitude where temperature is not too high.
Dr Yang: On Mars, you can have large robotic rovers with protruding arms and cameras all around. On Venus, the high temperatures and pressures mean that landers are generally shaped like a metal sphere to better withstand the pressure, with specialised and far simpler mechanisms that can withstand the heat. These landers do not last very long, at most an hour or two, and are mostly immobile.
Q: What further studies must be done to prove the presence of phosphine on Venus and to narrow down its origin?
Dr Yang: The phosphine detection on Venus looks quite robust with detections from two different telescopes. There will probably be other groups that will try to verify that detection, and possibly even look at the raw data independently.
Narrowing down the source of phosphine is going to be a lot more complicated, and may involve spacecraft to get a closer look at the chemistry of the atmosphere. What is more likely to happen is that people may now be interested to try to detect other biosignature molecules to corroborate the idea that phosphine on Venus is biologically generated.
Q: What do you think will be the implications of this finding for possible missions to Venus?
Dr Ng: This finding may motivate future flyby missions to observe the atmosphere of Venus up-close. It may even motivate sample-returning missions to collect aerosol from Venus’ atmosphere.
About the experts
Dr Cindy Ng is a Senior Lecturer at the NUS Department of Physics, and her research interests are dark energy models, testing models with observational data, and cosmography.
Dr Abel Yang is a Lecturer at the NUS Department of Physics, and he is interested in galaxy clustering, the large-scale structure of the Universe, astroinformatics, and astronomy education.