Of all the places in the solar system, life only exists on Earth. Or so we’ve been told. However, even though we’ve not—officially—found traces of life anywhere else in the solar system, theories say it likely exists in several places; Mars, Europa, Enceladus, even Ceres, but also Venus.
The latter is something that has widely been speculated for more than half-a-century, where various papers tried tacking the possibility of life prospering on Venus.
A revisited hypothesis delves into the actual possibility wherever there could be life in the Venusian clouds, floating in the atmosphere in an aerial biosphere. A study published in the journal Astrobiology looks into a possible aerial biosphere in the atmosphere of Venus, and where small microbial-type particle floats freely or is confined to the liquid environment within the cloud droplets.
The study proposes that alien life must reside within liquid droplets, which protect it from a fatal net loss of liquid to the atmosphere, which scientists describe as “an unavoidable problem for any free-floating microbial life forms.”
With a devastating greenhouse effect, crushing surface pressure, and clouds of sulfuric acid, Venus is certainly not friendly to life, at least not life as we know it.
Just how alien Venus actually is hasn’t been widely studied. That’s because Venus is, unlike Mars, a very harsh planet with a crushing environment. The few spacecraft humanity has sent to the surface of Venus have only survived for minutes, which doesn’t allow for detailed studies to be carried out from the surface.
While the surface of Venus is likely inhospitable to life as we know it, things are different some 40 to 60 km above the surface. Venus’ atmosphere is the most Earth-like of any other place in the Solar System. There, between 40 and 60 kilometers above the rocky landscape, Venus has an air pressure of about 1 bar and temperatures in the range of 0 ° C to 50 ° C.
On Earth, microorganisms, mostly bacteria, can be dragged into the atmosphere, where they have been found living at altitudes of up to 40 kilometers. If they can survive on Earth, how likely is it that similar organisms can survive on Venus? As revealed by experts, on Earth, some microbes (both inside and outside droplets) are found to be metabolically active, even though there is no evidence, as of yet, of cell division.
According to astrobiologist Sara Seager, planetary scientist, and professor at the Massachusetts Institute of Technology, the chances are good. “We argue that life, if it exists in Venus’ atmosphere, must reside inside cloud liquid droplets for the majority of its life cycle,” the researchers wrote.
The study explains that microbes could have a sustained “life cycle” in Venus’ atmosphere, allowing them to survive for perhaps millions of years. This is perhaps unsurprising, as the Venusian cloud decks have often been described by scientists as a potentially habitable environment.
If this is accurate, and there is microscopic, microbial life in Venus’ atmosphere, what are the chances of life existing in similar places on distant moons or even planets?