Could life ever arise on the planet Venus? That is, Venus as it exists today. Venus is a hellish place, with temperatures of around 462°C at the surface, rain composed of sulfuric acid, lava-flows over much of the surface, and an atmospheric pressure around 90 times that of Earth at sea level. It’s not a pleasant place, and a manned spacecraft would find it difficult to land there, and it might be even more difficult for humans to get out and walk around. In fact, I think we can dispense with the possibility of humans walking on Venus’s surface for the foreseeable future.
Many billions of years ago, some scientists speculate, Venus may have had a climate similar to Earth. Water may have been present in abundance, enough to fill relatively shallow oceans. An atmosphere of oxygen may have existed that could have been conducive to life. But if it did, under the influence of the heat from the sun (Venus gets about twice as much sunlight as Earth) the oceans boiled away, the water was split by ultraviolet light into hydrogen and oxygen, the hydrogen escaped into space, and the oxygen combined with carbon on the surface to form carbon dioxide, and the greenhouse effect took over. That pushed the temperature into the stratosphere. So to speak. And here we stand today.
But the presence of water making life possible on Venus in the distant past isn’t what I want to hypothesize in this post. I’m thinking about the possibility of life on Venus as it exists now. Yes, in the presence of all that heat, lava, pressure, and sulfuric acid. Earlier, on March 13, 2011, in a blog post entitled “Life–A New Definition,” I suggested that life on any arbitrary planet should be defined as “that which arises . . . under the influence of the energy from its sun over and above any other milieu . . . .” That’s without regard as to what the life forms look like, or what they’re composed of, or how they replicate, or any other limiting factor we may require to define life on Earth. We can’t think of life on other planets within the limited range we find here on Earth.
So, what would life on Venus look like now? Under the influence of that tremendous heat and pressure, chemical reactions are running wild, at least in comparison with Earth. That might be a good thing. It might be the very factor that makes “life” viable on the surface. Lava may stay liquid all the time on Venus. Possibly a life form could arise composed of lava globules that slowly creep across the surface, consuming other bits of the ground, extracting necessary elements, metabolizing them by sulfuric acid digestion, and eventually dividing into smaller globules that continue the process. And that’s just one scenario. I’m sure others could be visualized by those who are better at chemistry than I, so there’s no sense in me speculating much further here.
I certainly realize that the chance of “life” actually existing on the surface of Venus is probably very low, and that speculating about what it looks like could be a somewhat unscientific pursuit. But the real reason for looking at Venus this way (sorry about that) is that it gives us a different way of looking at life in general all across the galaxy. (Think what it would mean if we did find some sort of life on Venus.) Life certainly exists on (a few? many?) other planets somewhere in our galaxy because there are so many of them, and we should always be aware that it won’t necessarily look like us. It may be so vastly different that we may not recognize it at first, and we have to remain open to any possible physical form, and any possible metabolic form. Temperature and pressure won’t necessarily be a limiting factor.