You don’t want to live on Venus, but there are a lot of places you don’t want to live on Earth as well. Hydrothermal vents, acidic lakes and the cold reaches of the upper atmosphere are all pretty inhospitable plants and animals alike, but that doesn’t mean that they’re not home to life. As we look closer at the nastiest, hottest, most acidic bits of real estate on the planet, the more bacteria we find adapted to these extreme conditions. This has scientists excited, because if life is in the market for these spots on Earth, there’s a small but real chance that it might love what’s available on Venus.
Too hostile to be a home?
Don’t feel bad if you’re not familiar with the brutal conditions on Venus. It’s such a rough part of the solar system that the probes we’ve sent to the second planet generally don’t last very long; the Soviet Venera 13 set records by surviving for a whole 127 minutes. Aside from a few photographs, we have been able to determine that the surface of Venus gets up to 863º Fahrenheit, and the air pressure is between 17 to 20 times as strong as on Earth. With the wind and acidic chemistry in the air, even the heartiest Earth-born bacteria couldn’t survive on Venus’ surface. On the other hand, the upper atmosphere may be just gentle enough to allow microbes a small chance at survival.
The upper layers of clouds on Venus are reflective and acidic, made mostly of carbon dioxide, water and sulfuric acid. It doesn’t sound pleasant, but the temperatures are low enough that life as we know it could exist there. What’s more, the sulfuric acid may even be a byproduct of microbial metabolisms– species on Earth are already known to do that (often with unfortunate consequences for their surroundings.) What’s more, observations from space have noted unexplained dark patches in these Venusian clouds, most of which are within the size range of bacteria on our own planet. This isn’t proof of alien life, but since we’ve never tested specifically for organic chemistry in Venus’ upper atmosphere, we can’t rule out the possibility of microbes without getting more information.
While spacecraft are circling Venus in space, none of them are in a position to sample these dark spots in the planet’s clouds. One proposed design is the Venus Atmospheric Maneuverable Platform (VAMP), which would fly through caustic clouds for as long as a year. With the right set of sensors, like mass spectrometers and microscopes to examine airborne samples, researchers would be in a better position to identify potentially organic materials in the atmosphere.
Originating from the past, or other planets
As hard as it is to picture life on such a harsh planet, there are actually a few possibilities for how bacteria could end up there. The first option is that the bacteria migrated from the ground, since Venus was probably a nice place 2.9 billion years ago. At that time, there’s a fair chance that the planet was a tepid 51° Fahrenheit on the surface, giving microbes a chance to evolve before the upper atmosphere was the only place left to go. Alternatively, the clouds could have been seeded by a place like Earth, as high-speed dust moving through the solar system has been calculated to be able to knock microbes in our atmosphere clear into space. So if life didn’t arise on Venus on its own, there’s still a chance that other Earthlings simply beat us to the punch of traveling to another planet.
Source: Is there life adrift in the clouds of Venus? by University of Wisconsin-Madison, Science Daily