As countries including India prepare to send spacecraft and balloons to Venus, a new study dashes hopes of finding life in the clouds hovering above the planet. Researchers have found no evidence of chemical fingerprints that could raise the possibility of life ever existing in the thick clouds.
Led by researchers from Cambridge University, the study used a combination of biochemistry and atmospheric chemistry to test the ‘life in the clouds’ hypothesis, which astronomers have speculated about for decades. They found that life cannot explain the composition of the Venusian atmosphere.
The study published in the journal Nature Communications states that it has been proposed that abundant Venusian life could obtain energy from its environment using three possible sulfur energy-metabolisms. The new results could still be useful for studying the atmospheres of similar planets throughout the galaxy.
We’ve spent the past two years trying to explain the weird sulphur chemistry we see in the clouds of Venus. Life is pretty good at weird chemistry, so we’ve been studying whether there’s a way to make life a potential explanation for what we see,” co-author Dr Paul Rimmer from Cambridge’s Department of Earth Sciences said in a statement.
The team used a combination of atmospheric and biochemical models to study the chemical reactions that are expected to occur, given the known sources of chemical energy in Venus’s atmosphere. Venus has long been known as Eart’s mysterious twin that has been scarred for millions of years due to extreme climatic changes.
The team looked at a particular feature of the Venusian atmosphere the abundance of sulphur dioxide (SO2). On Earth, most SO2 in the atmosphere comes from volcanic emissions. On Venus, there are high levels of SO2 lower in the clouds, but it somehow gets sucked out of the atmosphere at higher altitudes.
The model included a list of metabolic reactions that lifeforms would carry out in order to get their ‘food’, and the waste by-products. The researchers ran the model to see if the reduction in SO2 levels could be explained by these metabolic reactions and found that the metabolic reactions can result in a drop in SO2 levels, but only by producing other molecules in very large amounts that aren’t seen.
“If life was responsible for the SO2 levels we see on Venus, it would also break everything we know about Venus’s atmospheric chemistry. We wanted life to be a potential explanation, but when we ran the models, it isn’t a viable solution. But if life isn’t responsible for what we see on Venus, it’s still a problem to be solved there’s lots of strange chemistry to follow up on,” Sean Jordan from Cambridge’s Institute of Astronomy, the paper’s first author said.
Researchers say their method of analysing atmospheric signatures will be valuable when the James Webb Space Telescope, the successor to the Hubble Telescope, begins returning images of other planetary systems later this year.