Venus’ surface is extremely inhospitable: hot enough to melt lead, sulphuric acid lingers and makes up the best part of the planet’s atmosphere. Yet, only a few months ago, scientists for the first time found evidence for life on Earth’s scorching neighbour. Researchers at Cardiff University shocked the astronomical community after they identified traces of phosphine – a key biological signature of life – in Venus’ atmosphere.
The discovery was nothing short of a paradox: with soaring temperatures and lack of oxygen the gas should technically disappear within minutes if it ever pops into existence.
Thus, the search for life on Venus had rarely crossed the minds of scientists.
Efforts had largely been focused on Mars and Jupiter’s moons, for example, Europa, which is thought to have stores of frozen lakes and freshwater.
Now, researchers are calling for endeavours into alien life to change tack, and begin closer to home.
Life on Venus: Search for alien life should begin on Venus, an astronomer claimed (Image: GETTY)
Venus: The planet’s surface is extremely inhospitable (Image: GETTY)
Dr Mark A Garlick noted that there are several other places in the Solar System touted as potential abodes of life, but are as of yet undiscovered.
He reasoned: “But among these worlds, it’s Venus that is the easiest to reach.
“At an altitude of 50km, floating habitats would be the ideal launch pad from which to search for signs of life in the clouds.
“Perhaps our search for extraterrestrial cousins among the planets should begin there.”
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Venus: The planet’s surface is extremely inhospitable (Image: GETTY)
It came as the astronomer weighed up the evidence for the existence of lifeforms on Venus – what he described as the “hellish world” in a report for the BBC’s Sky at Night magazine.
At face value, Venus is the antithesis to everything that sustains life.
The atmospheric ground pressure is 93 bar, similar to that beneath 900m of water on Earth; the sky, meanwhile, acts more like a fluid than a gas.
It is so dense that winds can move small rocks with ease.
Yet, it is widely accepted that billions of years ago Venus, Earth and Mars had similar genetic makeup, where similar distances from the Sun, and were formed from the same rocks and metals.
If life took root here, on Earth, it might well have done so on our neighbours, the only difference being climate catastrophes having devastated Venus and Mars.
Despite its soaring temperatures, Venus is only a heat trap on its surface.
At an altitude of 50km, Dr Garlick explained that the atmospheric pressure drops to 1 bar, the temperature comparable to a temperate day on Earth.
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Terraforming: How Venus might look should scientists terraform the planet and reforest the surface (Image: GETTY)
Microbial life: Bacteria could live in Venus’ atmosphere just as life does on Earth (Image: GETTY)
This is Venus’ habitable zone; whether or not life could flourish in this goldilocks region is to be seen.
Dr Garlick said: “Venus is an extremely cloudy world: only 20 percent of incident sunlight percolates down to the surface.
“Yet the atmosphere is not quite featureless; contrast-adjusted photos reveal the presence of dark patches or bands, which are particularly visible at ultraviolet wavelengths.
“These so-called ‘unknown absorbers’, discovered more than a century ago, are caused by mysterious substances that block most ultraviolet light and a portion of visible light, rendering these regions comparatively dark.”
Sky at Night: Dr Garlick said the discovery of phosphine was overly exciting in the search for life (Image: BBC)
In a 2019 study, researchers at the Technical University of Berlin explored the source of these dark patches.
They were unable to satisfactorily explain their formation and absorption properties.
What we do know, however, is that these unknown materials are comparable in size to light-absorbing bacteria on Earth, and they exhibit a similar absorption profile.
The discovery of phosphine, then, was another feather in Venus’ cap: it established that there must be biologically created.
But scientists have yet to identify other chemical processes that can make it there.
And, as other observers have noted, phosphine could be produced by some process that humans have not yet discovered.
Phosphine: It is a simple structure that indicates the existence of life whenever it is present (Image: GETTY)
Yet, it is this gap in knowledge that Dr Garlick says is the most “exciting” element of the discovery.
He said: “Phosphine, and the unknown substances absorbing ultraviolet light, taken together make a good case for studying the subject more closely.”
On Earth, microbial life is everywhere.
Thus, the proposition that bacteria survives in the reaches of Venus’ atmosphere isn’t as ludicrous as it might first seem – bacteria swept up in water particles to Earth’s atmosphere can survive at altitudes as high as 4km.
Life in these conditions would be, as Dr Garlick put it, “undoubtedly very hardy”.
But, vitally, not impossible.
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