Daein Ballard / Wikipedia
Artist’s conception of the process of terraforming Mars.

There is a dream that we at one point travel to Mars and terraform the planet so that it becomes a bit more habitable for us Earthlings to live on. According to a new study, however, it may be difficult, as the most popular theory of how to terraform Mars does not seem to hold.

Science fiction have long featured terraforming, the process of creating an Earth-like or habitable environment on another planet. Scientists have also proposed terraforming to enable the long-term colonization of Mars. A solution common to both groups is to release carbon dioxide gas trapped in the Martian surface to thicken the atmosphere and act as a blanket to warm the planet.

Researchers have long suggested that the large amounts of carbon dioxide found frozen on the planet and also found in the soil could be released in order to create a thicker atmosphere more like the one we have here on Earth. Of course, this would not allow us to breathe in the air on Mars, but it could heat the planet somewhat, which I suppose is a beginning in any case.

This infographic shows the various sources of carbon dioxide on Mars and their estimated contribution to Martian atmospheric pressure. Credit: NASA

In the study, “Inventory of CO2 Available for Terraforming Mars,” researchers have analyzed the carbon dioxide availability on Mars with data collected over the years. They have now found that there is probably not enough carbon dioxide on the planet to use this to create a thicker atmosphere. In the study you write:

“These results suggest that there is not enough CO2 remaining on Mars to provide significant greenhouse warming were the gas to be emplaced into the atmosphere; in addition, most of the CO2 gas in these reservoirs is not accessible and thus cannot be readily mobilized. As a result, we conclude that terraforming Mars is not possible using present-day technology.”

Terraforming (literally, “Earth-shaping”) is a process of deliberately modifying its atmosphere, temperature, surface topography or ecology to be similar to the environment of Earth to make it habitable by Earth-like life.

Although Mars has significant quantities of water ice that could be used to create water vapor, previous analyses show that water cannot provide significant warming by itself; temperatures do not allow enough water to persist as vapor without first having significant warming by CO2, according to the team.

The atmospheric pressure on Mars is around 0.6 percent of Earth’s. With Mars being further away from the Sun, researchers estimate a CO2 pressure similar to Earth’s total atmospheric pressure is needed to raise temperatures enough to allow for stable liquid water.

The most accessible source is CO2 in the polar ice caps; it could be vaporized by spreading dust on it to absorb more solar radiation or by using explosives. However, vaporizing the ice caps would only contribute enough CO2 to double the Martian pressure to 1.2 percent of Earth’s, according to the new analysis.

Another source is CO2 attached to dust particles in Martian soil, which could be heated to release the gas. A third source is carbon locked in mineral deposits. Using the recent NASA spacecraft observations of mineral deposits, the team estimates the most plausible amount will yield less than 5 percent of the required pressure, depending on how extensive deposits buried close to the surface may be. CO2 trapped in water-ice molecule structures, should such “clathrates” exist on Mars, would likely contribute less than 5 percent of the required pressure.

Carbon-bearing minerals buried deep in the Martian crust might hold enough CO2 to reach the required pressure, but the extent of these deep deposits is unknown, not evidenced by orbital data, and recovering them with current technology is extremely energy intensive, requiring temperatures above 300 degrees Celsius (over 572 degrees Fahrenheit). Shallow carbon-bearing minerals are not sufficiently abundant to contribute significantly to greenhouse warming, and also require the same intense processing.

“There is not enough CO2 left on Mars in any known, readily accessible reservoir, if mobilized and emplaced into the atmosphere, to produce any significant increase in temperature or pressure,”

– They write.

The team concludes that simply too much of Mars’ atmosphere has been stripped away by solar wind and radiation. According to estimates, the atmosphere that presently remains will entirely disappear over the next 2 billion years. The CO2 and water once present is vast quantities, they add, is likely gone forever.

“We’re getting away from the science here, but I would question the rationale for terraforming to begin with,”

“Having a back-up planet in case we screw this one up, or it gets screwed up from external drivers, I think is a poor argument. It’s a lot easier to keep this one pleasant and with a clement climate than it is to change the Mars environment.”

– Bruce Jakosky, a planetary scientist at the University of Colorado and co-author, with Northern Arizona University’s Christopher Edwards, of the new paper, told Wired.

While dreams of skipping through Martian fields might be dashed, for now, it’s likely that the red planet will still one day host human colonists in our mission to explore the solar system. The technology hurdles required for that may yet appear daunting, but it is undeniable that we humans will continue to advance, our knowledge and our technology will keep on developing. And future technologies may allow humanity to change Mars in ways not possible today.