It’s not likely that you’ll ever be offered the opportunity to visit Venus. But on the odd chance you are, you might want to decline. The temperature on the surface of the planet is around 870° F (465° C)—hot enough to melt lead—and the atmospheric pressure at Venusian sea level (not that there are any seas) is 92 times what it is on Earth.
But if it’s unlikely you — or any other organism — could survive on the surface of Venus, it’s possible things could be very different up in the Venusian clouds. According to a new study published in the journal Astrobiology, the temperature, pressure and chemistry of the atmosphere 30 miles above ground may be just right for vast colonies of otherworldly bacteria to survive.
That there may be airborne life on Venus is not an entirely new idea. The planet is generally believed to have once been running with water as Earth is now, but it lasted only between 650 million to two billion years before boiling off into the clouds. Earth, however, needed less than a billion years to develop microbial life. If the same happened on Venus, its microbes would not have had to vanish when the water did. Earthly bacteria have routinely been sampled up to 25 miles high, swept aloft by winds and surviving perfectly well in the wet, comparatively temperate conditions at those altitudes. Venusian bacteria could have done the same.
The new paper makes a strong case for that scenario, analyzing the conditions in the planet’s sky and finding them hospitable to biology. The first two boxes for sustaining life—tolerable temperature and pressure—are easily checked. Thirty miles above ground, Venus’s air pressure is roughly equivalent to the 15 pounds per square inch on the ground on Earth. The temperature, meantime, is a hot but survivable 140° F (60° C).
The chemistry of Venus’ atmosphere is decidedly different from Earth’s: Principally sulfuric acid, carbon dioxide and water droplets. But different is not necessarily deadly.
“On Earth, we know that life can thrive in very acidic conditions, can feed on carbon dioxide, and produce sulfuric acid,” said Rakesh Mogul, a co-author of the paper and a professor of biological chemistry at California State Polytechnic University, Pomona, in a statement that accompanied the paper’s release. Indeed, if life on Earth has proven anything, it’s that it can survive in exceedingly unlikely places—in boiling hot springs and hydrothermal vents, and locked in permafrost. All of those organisms can serve for models for extraterrestrial life.
Even more compelling, argue the authors, are dark patches in Venus’s atmosphere that change shape, size and position over time, but never disappear completely. Discovered in the early part of the 20th century, the patches had long been a mystery, but modern-day analyses have shown them to be made principally of particles that closely match the size of common Earthly bacteria. What’s more, the spectra of light the Venusian particles absorb closely match the spectra absorbed by those bacteria. Mogul and lead author Sanjay Limaye, of the University of Wisconsin, Madison, compare the atmospheric blooms to algae blooms in the oceans on Earth, arguing that they could be just as biologically robust.
Sending astronauts to study Venus more closely was not always a non-starter like it is today. Back in the days just after the first lunar landings, there was talk of repurposing an Apollo moon ship for a 400-day round trip flyby of Venus, but the year-plus journey for so brief a period in Venus’s neighborhood was ultimately deemed impractical. The old Soviet Union sent multiple robotic missions to Venus and in 1982, its Venera 13 spacecraft sent back the first color pictures from the surface.
Even now, the Northrup Grumman corporation is developing a spacecraft called the Venus Atmospheric Maneuverable Platform (VAMP), a lightweight winged craft that would be able to fly through Venus’s atmosphere while sampling it for biology. NASA would have to approve and fund the mission before it goes anywhere at all. That, given the space agency’s chronically tight budgets, is never a sure thing. Still, the possibility of life can change priorities fast—and Venus may all at once have a promise we never knew.