Venus wants to kill you.
With its sulfuric acid clouds, dangerously high atmospheric pressure, absurdly high surface temperature, et cetera, et cetera, Venus has more options for killing humans than any other planet in the Solar System. But maybe we can fix that. Maybe we can make Venus more like Earth.
To terraform Venus (or any other planet) we must do two things:
- Add stuff that we need to survive, like water and oxygen.
- Remove or mitigate conditions that would harm us.
Most discussions on terraforming seem to overlook that second part, perhaps because the biggest threats to life-as-we-know-it are not always immediately obvious.
Turning Venus into Earth
Converting Venus’s noxious atmosphere of CO2 and sulfuric acid into a friendly oxygen/nitrogen mix will require some creativity. Since I’ve never personally terraformed a planet (yet), I can only guess about the tools required; but my educated guess is that some sort of bioengineered algae would work best.
We’d need something that converts carbon dioxide into oxygen. Algae already do this. We’d need something that can endure prolonged exposure to sulfuric acid and solar radiation. Some species of bacteria can do that. We’d also need something that can survive, at least at first, in a high temperature environment where water is scarce. Again, life on Earth has already shown that this is possible. We just have to design a new species that puts all of these qualities together.
Once our bioengineered algae start gobbling up Venus’s CO2, removing Venus’s primary greenhouse gas, a process of global cooling should begin. Cooler temperatures would disrupt the sulfur cycle, so the sulfuric acid clouds would start disappearing on their own, and traces of water vapor in the upper atmosphere would be able to condense into liquid water.
Admittedly, this liquid water would only result in a few puddles, so we’d still have to transport in more water. Also, I’m not sure how to deal with the atmospheric pressure. But still, we’re off to an amazing start. Unfortunately, Venus has other plans.
Turning Venus Back into Venus
I sometimes joke that I want to live on Venus because I’d have so many more hours in my day to get stuff done. From sunrise to sunset, a day on Venus is over 2,800 hours long.
Venus has an abnormally slow rotation. In fact, compared to the rest of the Solar System, Venus is rotating backwards (the only planet weirder than Venus in this regard is Uranus, which rotates sideways).
2,800 hours of daylight can have some peculiar effects on a planet, especially an Earth-like planet. The oceans that our algae worked so hard to create would soon boil. Water vapor would act as a greenhouse gas. The planet’s carbon cycle would come to a grinding halt, allowing CO2 to accumulate in the atmosphere once again, and the rising temperatures would kick start a brand new sulfur cycle.
Without constant efforts by us to maintain cool temperatures on Venus, the planet would rapidly turn back into its old self. In the end, Venus kills you.
I normally end these posts with links to some of my sources, but today, I want to end with a book recommendation: Venus Revealed by David Grinspoon. Without getting into too much technical detail, Grinspoon covers many key topics related to Venus, including a brief but illuminating section on terraforming. The book is a wealth of knowledge not only on Venus but concerning planetary science in general (although the bits about exoplanets are now out of date).
UPDATE: The length of a day on Venus has been corrected in this post. According to this article from Universe Today, the time from sunrise to sunset equals 116.75 Earth days (which comes out to 2,802 hours). I apologize for my previous mistakes, in which I stated a figure of 1,400 hours and, before that, a mere 60 hours.