Earth's closest neighbor is about as close to a planetary evil twin as you can get. While very similar to Earth in terms of size, weight, and gravity, Venus—ironically named after the Roman goddess of love and beauty—is a blasted hellscape of extreme temperatures, crushing atmospheric pressure, and swirling clouds of sulfuric acid. Temperatures at the Venusian surface can be as high as 860 degrees Fahrenheit and the weight of that acid choked atmosphere is 90 times heavier than Earth. That's the equivalent pressure of being 2970 feet under the ocean. Despite these unfortunate characteristics, a paper published in the journal Astrobiology on March 30, 2018 by a team of NASA scientists says this deadly nightmare planet might be our best chance of finding extraterrestrial life—and we may have found it already.
While the idea of life on Venus is not new by any means, the recently published paper lays out a new argument based on new discoveries both on Venus and here on Earth. Sanjay Limaye, the lead author of the paper and, noticed that bacteria on earth can form light-absorbing colonies that share properties with unexplained "dark patches" in the clouds of Venus. These dark patches have been shown, through spectroscopic observation, to be composed of sulfuric acid and some "unknown particles."
Limaye and the other authors of the paper argue that these mysterious and unidentified particles could be bacterial life akin to an algae bloom that can survive the punishing atmosphere of the solar system's hottest planet. Limaye explains:
Venus shows some episodic dark, sulfuric rich patches, with contrasts up to 30–40 percent in the ultraviolet, and muted in longer wavelengths. These patches persist for days, changing their shape and contrasts continuously and appear to be scale dependent.
Strangely, the changing dark patches in Venus' atmosphere share the same dimensions as some bacteria on Earth. The problem is the instruments examining Venus aren't capable of distinguishing between organic and inorganic materials.
As far as chances for finding extraterrestrial life go, this one isn't bad. Some models of Venus' history suggest that Venus could have held a large amount of liquid water for as long as one billion years, which would have been a superb jumping off point for life to evolve and adapt to the changing environment. Recently, scientists have discovered a whole slew of bacteria and viruses on Earth that can survive at extreme temperatures and pressures, including some that make their homes in sulfuric acid.
To test this idea, however, we would need to actually send a craft to the Venus surface. Limaye hopes that NASA will send a VAMP (Venus Atmospheric Maneuverable Platform), a plane-blimp hybrid that could study the middle atmosphere of Venus for up to a year to study the planet's atmosphere and hopefully confirm his suspicions.
Currently, NASA is discussion possible collaboration in the Russian Venera-D mission, which will send an orbiter, lander, surface station and maneuverable aerial platform to Venus sometime next decade.