Mars was once an Earth-like world. Many people have suggested ideas of how we could revive the breathable air, running water, and magnetic protection that Mars now lacks making it a habitable option for humanity's future. But are any of these suggestions really possible?
Can We Make Mars Earth-Like Through Terraforming?
The concept of “terraforming” means to transform the conditions of an entire planet to make them habitable, like Earth.
About 4 billion years ago, Mars actually had lakes of liquid water and possibly flowing rivers. Combined with a thick atmosphere, a magnetic field to protect against radiation, and a variety of organic molecules, Mars had favorable conditions to form and support life as we know it.
But it probably didn’t remain habitable for long. The magnetic field was lost sometime between 3 to 4 billion years ago, which allowed the solar wind to strip away most of the planet’s atmosphere and surface water, turning Mars into the cold desert we see now. Today, the atmosphere on Mars is far too thin and cold to support liquid water on its surface. With atmospheric pressure that is less than 1% of Earth’s, any surface water would quickly evaporate or freeze.
So, could we reverse nature’s effects and transform Mars back into a habitable planet? Here’s what it could take, and why it’s unlikely it’ll happen.
First, the liquid water. In order for water to remain liquid on a planet, the atmospheric pressure needs to be just right. Some people have suggested that by exploding nuclear bombs over the polar caps on Mars, the heat would vaporize the frozen carbon dioxide and create greenhouse gases that would increase the atmospheric pressure and warm the planet. In theory, this would melt the water ice that we see on the surface of Mars, creating liquid water.
Aside from the ethical issues of nuking another planet, this plan would only be a temporary one. To get the atmospheric pressure high enough to sustain the water’s liquid form, you’d need to vaporize an extremely large amount of frozen carbon dioxide. Even if we mined Mars’ entire surface for carbon dioxide, the atmospheric pressure would still not be nearly enough to sustain liquid water.
Another alternative would be to artificially introduce gases that could trap heat even better than carbon dioxide. These kinds of gases are short-lived, though, so the process would need to be done repeatedly to keep Mars warm. And besides, it would be extremely costly to bring large amounts of these gases all the way to Mars.
Water aside, we Earthlings still can’t breathe on Mars. Getting oxygen into the atmosphere would be a crucial part of the terraforming.
One idea is to pull out the breathable oxygen, O2, from the carbon dioxide, or CO2, that is already in Mars’ atmosphere. On Earth, the atmosphere used to have almost no breathable oxygen. Around 2.5 billion years ago, microorganisms called cyanobacteria evolved. These tiny life forms began using photosynthesis to convert carbon dioxide in our atmosphere into breathable oxygen. Maybe microorganisms like this could help do the same for the Martian atmosphere, if they could survive long enough.
On the International Space Station, researchers have tested the ability of microorganisms to withstand non-Earth environments. In one test, some microorganisms survived in a container with Mars-like conditions for 533 days. That may seem like a long time, but a NASA study in 1976 concluded that it would take at least a few thousand years for these kinds of organisms to make a habitable atmosphere on Mars.
And then there’s the magnetic field. Even if we somehow managed to sustain liquid water on the Martian surface and oxygen in its atmosphere, the resulting Earth-like conditions would probably be short-lived.
Mars lacks a protective magnetic field, which means that solar wind is continuously stripping its atmosphere and water away. The work we’d put into terraforming Mars would be constantly undone by the Sun’s powerful influence.
To truly terraform Mars, we would need to restore its magnetic field. While we don’t have the technology to churn the core of a planet faster to revive its magnetic field, an artificial magnetic field placed between the Sun and Mars could in theory encompass Mars and protect it from the solar wind. If this idea sounds like something out of science fiction, it’s because we are nowhere close to having the technology to make it happen.
In short, it seems highly unrealistic that we could transform Mars into a more Earth-like planet any time soon. In the meantime, future Martian explorers will need to live in enclosed structures on the surface or underground to keep them warm and give them air to breathe.