What does finding microbial life in clouds of Venus mean? | Opinion
The discovery of phosphine on our next-door planet would give us two cases of life in the small handful of planets we’ve visited.
- Calvin H. Warner is a third-year law student at Vanderbilt. He is also an adjunct professor at Belmont University.
In the film "Contact," Jodie Foster gasps in disbelief as her satellites record a series of prime numbers beamed toward Earth from a distant star. This would be an unmistakable biosignature, a clear sign of intelligent life existing elsewhere in the universe.
It wasn’t that dramatic or unambiguous, but Massachusetts Institute of Technology researchers have made a significant breakthrough in the search for extraterrestrial life – on the planet right next door.
Phosphine is produced by life on Earth
On two separate occasions, once in Hawaii and once in Chile, scientists used powerful telescopes to identify phosphine gas in the clouds of Venus. Phosphine was already thought to be a biosignature because it is produced by life here on Earth and is difficult to produce in other ways. Researchers considered a variety of alternative explanations: meteoric impacts, volcanoes, lightning strikes and even the possibility that some microbe could have stowed away on one of our probes and found its way to the clouds of Venus (Answer: No. It would have needed to survive a 94-million-mile journey through space).
None of these theories could produce the level of phosphine that was detected. Further, Venus does not enjoy the same degree of ozone protection we do. Therefore, ultraviolet rays torch the planet’s atmosphere, which breaks down phosphine. The amount that researchers found can be explained only if something is replenishing the phosphine as the sun’s rays dissolve it.
The failure of alternative theories leaves researchers with the exciting possibility that the existence of microbial life on our galactic neighbor just might be the best explanation of the findings.
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Venus has not been of traditional interest to astrobiologists; their focus has been on Mars, Jupiter’s moon Europa, and distant exoplanets that suggest conditions similar to Earth. This is because Venus experiences surface temperatures approaching 900 degrees Fahrenheit, and while the temperatures cool in the upper atmosphere, the planet is choked by acid rain and crushing air pressure comparable to Earth’s deepest oceans. These conditions would exterminate any lifeform as we know them on Earth.
But researchers have an explanation for how life could exist even in this toxic climate. In the highest clouds some 40 miles above the surface, where the phosphine was detected, the temperature cools to balmier conditions, around 85 degrees Fahrenheit. This still doesn’t explain how these microbes would resist being cycled down to the surface and incinerated, or how they can live in an environment toxic to life as we know it on Earth.
'Living rain'
Study author Sara Seager suggested a form of “living rain” – microbial life forms living inside liquid droplets. These droplets would evaporate, causing the spores inside to float down through the atmosphere. The dried-out spore would become suspended in a cloud layer, waiting to be rehydrated and swept back up to repeat the cycle. This is just conjecture, but one possible way to explain extraterrestrial life inside the clouds.
The universe has repeatedly proven to be stranger than we suspect. While there is no proposed abiotic explanation for the finding of phosphine on Venus, there may yet be some geological or atmospheric process that produces phosphine in a way we don’t understand. Or there could be an undiscovered but abiotic element on Venus that gives off markers indistinguishable from phosphine. Any of those would be interesting in their own right, but the discovery of life on our next-door planet would give us two cases of life in the small handful of planets we’ve visited – in a universe with billions of worlds.
“We know that it is an extraordinary discovery,” lead author Clara Sousa-Silva told the New York Times. “We may not know just how extraordinary without going back to Venus.” NASA and other world space agencies were already contemplating missions to Venus. This discovery will no doubt give those efforts an extra boost.
Calvin H. Warner is a third-year law student at Vanderbilt. He is also an adjunct professor at Belmont University.