Venus, no, Jupiter, yes ... potentially

Venus is hot right now, with three missions expected to launch to the planet in the late 2020s. NASA/JPL-Caltec

Seems Venus is way too dry to sustain life if research by planetary scientists proves out to be true while Jupiter is a different story indeed.

The clouds of Venus have captivated Earthlings for decades. They form a dazzling mirror that obscures the planet's surface and, in the 1950s, one Israeli scholar even speculated that the clouds may hide a world teeming with insect life capable of enduring the extreme heat. 

When Russia's Venera spacecraft took images of the surface in 1975, there were no insects to be found. Venus is a desolate hellscape, the victim of a runaway greenhouse effect that has sent temperatures on the ground soaring to well over 850 degrees Fahrenheit -- hot enough to melt lead. But in the clouds, more temperate climes await any would-be alien lifeforms. 

Up in the atmosphere, life might just find a way.

At least, that was one hypothesis. It can happen on Earth... so why not elsewhere? Last year, the idea that microbes might call the atmosphere of Venus home was bolstered by a study that claimed to have discovered elevated levels of phosphine -- an unstable gas associated with biological activity -- in the cloud deck of our sister planet. That spawned the theory that microbes in the clouds could be producing the gas.

As scientists untangled the phosphine signal, though, the possibility that it was a sign of life in Venus' clouds looked less and less likely. 

On Monday, the likelihood of a drifting community of microbes in the clouds took another blow.

In a study published in the journal Nature Astronomy, researchers rule out the possibility of life -- as we know it -- existing in the Venusian clouds. The clouds are uninhabitable.

Why? Because ...

Any potential microbe floating through the Venus clouds would find itself in an extremely hostile environment. About 30 to 44 miles above the surface, up in the clouds, it's more dry than the Earth's most expansive subtropical desert: the Sahara.

"The Venus clouds are a whole order of magnitude more dry than the Sahara," said Hallsworth, noting that the Sahara has around 0.25 water activity, while the clouds of Venus come in at just 0.004 water activity. That figure for Venus  is simply far too extreme to support any life we know of. 

"The most dry-tolerant microbe on Earth wouldn't stand a chance in Venus," Hallsworth said. 

Venus is magnitudes more dry than the Sahara, the third-driest desert on Earth. Florian Kaiser/Getty

But Jupiter's a different story.

The gas giant Jupiter looms over all the planets that orbit the sun. It's monstrous and, like Venus, it's famous for its clouds. When the research team analyzed water activity in Jupiter's atmosphere, they found it was at a high enough level to permit habitation by microbes.

"We absolutely hadn't expected that," said Hallsworth. 

Using readings from NASA's Galileo probe, which launched in 1989 and released a probe into the gas giant's atmosphere in 1995, the team revealed somewhere beneath Jupiter's roiling, swirling face, there are conditions permissible for life. 

The water activity within Jupiter's roiling clouds are permissible for life. NASA/JPL-Caltech/SwRI/MSSS/Image processing by Kevin M. Gill

Arthur C. Clarke talked about life finding a way on Jupiter in 2010 Odyssey Two

A whole new chapter of evolution, as alien as that which he had glimpsed on Europa, was opening before him. There were jet-propelled torpedoes like the squids of the terrestrial oceans, hunting and devouring the huge gasbags. But the balloons were no defenseless; some of them fought back with electric thunderbolts and with clawed tentacles like kilometer-long chainsaws.

There were even stranger shapes, exploiting almost every possibility of geometry -- bizarre, translucent kites, tetrahedra, spheres, polyhedra, tangles of twisted ribbons... The gigantic plankton of the Jovian atmosphere, they were designed to float like gossamer in the uprising currents, until they had lived long enough to reproduce; then they would be swept down into the depths to be carbonized and recycled in a new generation.

Clarke may be right after all.

A probe to Jovian clouds would be cool without question. :)