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Predict

There’s No Life on Venus After All

Recent study changes everything

Scientists had hope for microbial life on our sister planet just a month ago.

Last month’s headlines conveyed a startling image: the possibility of life on Venus. Venus is many things — bright, sultry, wispy, rich — but it’s never been seen as hospitable to life. It lacks oxygen and oceans, harboring instead rows of sulfuric acid clouds in its orange skies. These clouds trap heat and encourage a runaway greenhouse effect that drives temperatures up to 900 degrees Fahrenheit (465 degrees Celsius). A smoldering, golden environment filled with thick clouds and the bodies of spacecraft we’ve sent in the past. Most spacecraft able to land on the planet’s surface last mere minutes before the intense heat and pressure destroys them. Venera 13 lasted two hours. For comparison, the Opportunity rover survived 14 years on Mars. Venus may be named after the goddess of love and beauty but it is not a loving place towards life at all. This is what made the headlines so startling.

The excitement derived from two separate studies. One using the James Clerk Maxwell Telescope (JCMT) and one using the Atacama Large Millimeter Array (ALMA). Both confirmed the presence of phosphine in the upper atmosphere of Venus. This result was completely unexpected.

Phosphine is a chemical that can be produced abiotically but is more often created by bacteria here on Earth. This close tie to living organisms makes it a biosignature — a strong indicator for the presence of life. While phosphine is sometimes made in laboratory conditions and through volcanic activity, this is not what researchers believed to be causing the phosphine spike on Venus. The studies suggested the phosphine level reached 20 parts-per-billion (PPB), a significant amount.

The gas giants Saturn and Jupiter also produce phosphine. The intense pressures of their atmospheres use free atoms of hydrogen to make the chemical, but this is not the mechanism behind the phosphine on Venus.

Any abiotic process able to make phosphine would have been millions of times too weak to give us the 20 PPB result. And it has been hypothesized for decades now that microbial life — and even more complex organisms — could exist on Venus. But what creatures would possibly make a home there? The atmosphere is unspeakably dry, acidic, and unwelcoming. Except in the regions where it isn’t.

Venus’s atmosphere is a gradient. 30 miles (48 km) up from the cratered surface the temperatures and pressures become much more inviting, similar to those of Earth. These top cloud layers are where life could exist. The organisms would most likely be airborne microbes living in droplets that contain a small amount of water. Instead of ever touching the surface where conditions would kill the microbes, the droplets are in a closed cycle of falling towards the surface and evaporating. A loop that hardy organisms could possibly survive.

We must also keep in mind that Venus wasn’t always the stark, unliving desert that it is today. A few hundred million years ago it may have been home to water, and to conditions more agreeable with life. Just as we speculate in the theory of panspermia that organisms could have been transferred between Earth and Mars at some long ago time, so too might life have been transferred between Earth and Venus. Atmospheric grazing events — where passing asteroids gently graze the Earth — would have spread microbes living on our planet’s upper atmosphere to the asteroids headed Venus’s way. Researchers show that over 600 of these Earth-to-Venus grazing events have already occurred.

A simulation shows Venus looking Earth-like in the past. Image by NASA.

However, any life that developed when Venus was more hospitable would likely have died after the planet’s environment changed for the worse. New research reveals that any hopes we had of observing life on Venus today is about to die, too.

An independent team decided to reanalyze the claims about phosphine on Venus. They compared the data from ALMA and JCMT to existing data of Venus’s infrared radiation. The phosphine should have appeared in the planet’s spectrum but, despite the infrared data being gathered over several years, only one month in the year 2015 showed any significant readings of phosphine. This new research suggested that instead of the original and exciting claim of 20 PPB of phosphine in the Venusian atmosphere, there was only a max of 5 PPB.

In light of this new information one might draw the conclusion that there was a flaw in the way the original data was analyzed. The method of the original analysis team lead to certain spectral features having exaggerated importance and thus creating a false result. One of the main problems came with the method of noise-removal from the data. When the new study used a different method of noise-removal, the original phosphine signal didn’t appear. In fact, when the new team used the original team’s flawed method of analyzation, they could draw any number of false conclusions from the data.

The biosignature of phosphine could be nothing more than an illusion.

Phosphine molecules in the atmosphere of Venus. Image by ESO/M. Kornmesser /L. Calcada

We cannot yet reach a definitive stance on the matter. Further reanalysis of the original data will reveal whether or not it was just flawed science, but the idea of life on Venus has certainly had a strong shadow cast on it once again.

But Venus was never a strong contender in the search for life outside of Earth. It remains instead our planet’s sister. Its resplendent body is closer to us than any other planet in the Solar System. Because of this it appears as the third brightest point of cosmic light in our skies, dimmer only than the moon and the sun. We cannot look to it for signs of life. But we can take its hellish environment as inspiration to keep our planet from turning into more of the same. We may even one day decide to colonize its skies, living there like a wiser people out of a science fiction tale. We’d be making a new home in a strange sort of heaven: golden hills below, and all around us the silent paradise of lifeless clouds.

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Ella Alderson

Ella Alderson

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Astrophysics student, writer for over a decade. A passion for language and the unexplored universe. I aim to marry poetry and science. ella.aldrsn@gmail.com