Terraforming Mars Just Got a Lot Harder

The act of terraforming a planet, even one as comparatively hospitable as Mars, would never be an easy task. But whenever discussing mankind's future on the Red Planet, it seemed to be the inevitable conclusion. We would colonize Mars, and then change it in Earth's image. It would be a daunting task of engineering, and the ethical dilemma of uprooting any potential native life was not going to go away either, but it almost seemed a foregone conclusion that we would eventually terraform Mars.

Mars is probably going to stay red in the future.

According to data from the MAVEN space probe currently orbiting Mars and studying the Martian atmosphere, however, there may be a big problem with future terraforming endeavors. The infant Mars had a thick atmosphere, but as time went on, that atmosphere was lost. It was assumed that most of the carbon dioxide that originally made up the atmosphere had frozen out into the soil, but that is not the case. Once Mars lost its magnetic field, the solar wind, more active when the Sun was young, pummeled the planet, and Mars, already much smaller and with much weaker gravity than Earth, had no way to hold onto its atmosphere. It took maybe around 500 million years, and by around 3.7 billion years ago, the Mars we know today had taken shape. 

Why is this bad for terraforming? Well, if the carbon dioxide had settled into the Martian soil, warming the planet back up again would release it, building up the atmosphere and setting up a greenhouse effect (a good thing in this case), which would heat the planet up even more, releasing even more carbon dioxide and so on. But the carbon dioxide from the original Martian atmosphere is just gone, lost forever to the cosmos. There is still some on the surface, frozen in the ice caps, but likely not enough to work with. This news does not necessarily mean Mars cannot be terraformed, but in order to do so, it's going to take more than just warming the place up.