Uh oh, Mars Doesn’t Have Enough Carbon Dioxide to be Terraformed

For almost a century now, the concept of terraforming has been explored at length by both science fiction writers and scientists alike. Much like setting foot on another planet or traveling to the nearest star, the idea of altering an uninhabitable planet to make it suitable for humans is a dream many hope to see accomplished someday. At present, much of that hope and speculation is aimed at our neighboring planet, Mars.

But is it actually possible to terraform Mars using our current technology? According to a new NASA-sponsored study by a pair of scientists who have worked on many NASA missions, the answer is no. Put simply, they argue that there is not enough carbon dioxide gas (CO2) that could practically be put back into Mars’ atmosphere in order to warm Mars, a crucial step in any proposed terraforming process.

The study, titled “Inventory of CO2 available for terraforming Mars“, recently appeared in the journal Nature Astronomy. The study was conducted by Bruce Jakosky – a professor of geological sciences and the associate director of the Laboratory for Atmospheric and Space Physics (LASP) at the University of Colorado, Boulder – and Christopher S. Edwards, an assistant professor of planetary science at Northern Arizona University and the leader of the Edwards Research Group.

The study was supported in part by NASA through the Mars Atmospheric and Volatile EvolutioN (MAVEN) and Mars Odyssey THEMIS (Thermal Emission Imaging System) projects. Whereas Professor Jakosky was the Principal Investigator on the MAVEN mission, Professor Edwards is a participating scientist on the Mars Science Laboratory Curiosity Rover (MSL), and worked on the Mars Odyssey THEMIS mission (among other Mars missions).

As we explored in a previous article, “How Do We Terraform Mars?“, many methods have been suggested for turning the Red Planet green. Many of these methods call for warming the surface in order to melt the polar ice caps, which would release an abundant amount of CO2 to thicken the atmosphere and trigger a greenhouse effect. This would in turn cause additional CO2 to be released from the soil and minerals, reinforcing the cycle further.

According to many proposals, this would be followed by the introduction of photosynthetic organisms such as cyanobacteria, which would slowly convert the atmospheric CO2 into oxygen gas and elemental carbon. This very method was suggested in a 1976 NASA study, titled “On the Habitability of Mars: An Approach to Planetary Ecosynthesis“. Since that time, multiple studies and even student teams have proposed using cyanobacteria to terraform Mars.

However, after conducting their analysis, Professors Jakosky and Edwards concluded that triggering a greenhouse effect on Mars would not be as simple as all that. For the sake of their study, Jakosky and Edwards relied on about 20 years of data accumulated by multiple spacecraft observations of Mars. As Edwards indicated in a recent NASA press release:

“These data have provided substantial new information on the history of easily vaporized (volatile) materials like CO2 and H2O on the planet, the abundance of volatiles locked up on and below the surface, and the loss of gas from the atmosphere to space.”

Scientists were able to gauge the rate of water loss on Mars by measuring the ratio of water and HDO from today and 4.3 billion years ago. Credit: Kevin Gill

To determine if Mars had enough gases for a greenhouse effect, Jakosky and Edwards analyzed data from NASA’s Mars Reconnaissance Orbiter (MRO) and Mars Odyssey spacecraft to determine the abundance of carbon-bearing minerals in Martian soil and CO2 in polar ice caps. They they used data from NASA’s MAVEN mission to determine the loss of the Martian atmosphere to space. As Prof. Jakosky explained:

“Carbon dioxide (CO2) and water vapor (H2O) are the only greenhouse gases that are likely to be present on Mars in sufficient abundance to provide any significant greenhouse warming… Our results suggest that there is not enough CO2 remaining on Mars to provide significant greenhouse warming were the gas to be put into the atmosphere; in addition, most of the COgas is not accessible and could not be readily mobilized. As a result, terraforming Mars is not possible using present-day technology.”

Although Mars has significant quantities of water ice, previous analyses have shown that water vapor would not be able to sustain a greenhouse effect by itself. In essence, the planet is too cold and the atmosphere too thin for the water to remain in a vaporous or liquid state for very long. According to the team, this means that significant warming would need to take place involving CO2 first.

However, Mars atmospheric pressure averages at about 0.636 kPA, which is the equivalent of about 0.6% of Earth’s air pressure at sea level. Since Mars is also roughly 52% further away from the Sun than Earth (1.523 AUs compared to 1 AU), researchers estimate that a CO2 pressure similar to Earth’s total atmospheric pressure would be needed to raise temperatures enough to allow for water to exist in a liquid state.

Artist’s rendering of a solar storm hitting Mars and stripping ions from the planet’s upper atmosphere. Credits: NASA/GSFC

According to the team’s analysis, melting the polar ice caps (which is the most accessible source of carbon dioxide) would only contribute enough CO2 to double the Martian atmospheric pressure to 1.2% that of Earth’s. Another source is the dust particles in Martian soil, which the researchers estimate would provide up to 4% of the needed pressure. Other possible sources of carbon dioxide are those that are locked in mineral deposits and water-ice molecule structures known as “clathrates”.

However, using the recent NASA spacecraft observations of mineral deposits, Jakosky and Edwards estimate that these would likely yield less than 5% of the require pressure each. What’s more, accessing even the closest minerals to the surface would require significant strip mining, and accessing all the CO2 attached to dust particles would require strip mining the entire planet to a depth of around 90 meters (100 yards).

Accessing carbon-bearing minerals deep in the Martian crust could be a possible solution, but the depth of these deposits is currently unknown. In addition, recovering them with current technology would be incredibly expensive and energy-intensive, making extraction highly impractical. Other methods have been suggested, however, which include importing flourine-based compounds and volatiles like ammonia.

The former was proposed in 1984 by James Lovelock and Michael Allaby in their book, The Greening of Mars. In it, Lovelock and Allaby described how Mars could be warmed by importing chlorofluorocarbons (CFCs) to trigger global warming. While very effective at triggering a greenhouse effect, these compounds are short-lived and would need to be introduced in significant amounts (hence why the team did not consider them).

NASA’s MAVEN spacecraft is depicted in orbit around an artistic rendition of planet Mars, which is shown in transition from its ancient, water-covered past, to the cold, dry, dusty world that it has become today. Credit: NASA

The idea of importing volatiles like ammonia is an even more time-honored concept, and was proposed by Dandridge M. Cole and Donald Cox in their 1964 book, “Islands in Space: The Challenge of the Planetoids, the Pioneering Work“. Here, Cole and Cox indicated how ammonia ices could be transported from the outer Solar System (in the form of iceteroids and comets) and then impacted on the surface.

However, Jakosky and Edwards’ calculations reveal that many thousands of these icy objects would be required, and the sheer distance involved in transporting them make this an impractical solution using today’s technology. Last, but not least, the team considered how atmospheric loss could be prevented (which could be done using a magnetic shield). This would allow for the atmosphere to build up naturally due to outgassing and geologic activity.

Unfortunately, the team estimates that at the current rate at which outgassing occurs, it would take about 10 million years just to double Mars’ current atmosphere. In the end, it appears that any effort to terraform Mars will have to wait for the development of future technologies and more practical methods.

These technologies would most likely involve more cost-effective means for conducting deep-space missions, like nuclear-thermal or nuclear-electric propulsion. The establishment of permanent outposts on Mars would also be an important first step, which could be dedicated to thickening the atmosphere by producing greenhouse gases – something humans have already proven to be very good at here on Earth!

Project Nomad, a concept for terraforming Mars using mobile, factory-skyscrapers from the 2013 Skyscraper Competition. Credit: evolo.com/Antonio Ares Sainz, Joaquin Rodriguez Nuñez, Konstantino Tousidonis Rial

There’s also the possibility of importing methane gas from the outer Solar System, another super-greenhouse gas, which is also indigenous to Mars. While it constitutes only a tiny percentage of the atmosphere, significant plumes have been detected in the past during the summer months. This includes the “tenfold spike” detected by the Curiosity rover in 2014, which pointed to a subterranean source. If these sources could be mined, methane gas might not even need to be imported.

For some time, scientists have known that Mars was not always the cold, dry, and inhospitable place that it is today. As evidenced by the presence of dry riverbeds and mineral deposits that only form in the presence of liquid water, scientists have concluded that billions of years ago, Mars was a warmer, wetter place. However, between 4.2 and 3.7 billion years ago, Mars’ atmosphere was slowly stripped away by solar wind.

This discovery has led to renewed interest in the colonizing and terraforming of Mars. And while transforming the Red Planet to make it suitable for human needs may not be doable in the near-future, it may be possible to get the process started in just a few decades’ time. It may not happen in our lifetime, but that does not mean that the dream of one-day making “Earth’s Twin” truly live up to its name won’t come true.

Further Reading: NASA

12 Replies to “Uh oh, Mars Doesn’t Have Enough Carbon Dioxide to be Terraformed”

  1. It is a simple and low cost solution.
    Put small boosters on asteroids with the needed materials, and set a trajectory that will cause them to impact Mars. This brings the needed gases to increase the atmospheric volume, as well as the chemicals needed for Terra forming. If comets can be used also, then that is for the better.
    The second advantage is that this will increase the mass of Mars which will help to hold the atmosphere. and possibly jump start a magnetic field.

  2. *sigh*
    How many years must it take before science “bloggers” get the fact that you can’t terraform a planet with a liquid core. No matter what gases or minerals the planet has.
    The terraformed atmosphere would just evaporate into space after a few weeks.

    1. *sigh*
      What are you high on? Either it is a horse or some chemical, just stop it. Get some help.
      And what is the connection between a liquid core and terraforming? Why it is a fact? Where is the theory of terraforming? Who got a Nobel Prize for it? And why would evaporate into space after such sort time? And if the terraforming process would take years, centuries or millennia, why would the evaporating wait for it to be completed to abruptly reverse it?
      Oh, I solved it. You just have to continuously terraform the planet, and be careful not to stop it for even a day enough to suddenly undo thousand of years of work, you know, like carefully planning maintenance stops between the terraforming machines, to keep at least one running all the time!

  3. Hope we’ve heard the last of it. It’s tedious to have to address how stupid this “idea” is. We can’t even terraform Earth and we’re right here. We can’t make the average temperature of the Earth go down one degree, and our future depends on it.

    1. Actually, that’s exactly what we’re doing to Earth. We’re terraforming it by putting tons of CO2 into the air and triggering a greenhouse effect, which is having the effect of changing its ecology and weather patterns. Applied to Mars, that same process would make the planet warmer, wetter, and more habitable.

  4. Ok, so there are actually TWO major atmospheric impediments to terraforming Mars, the second of which is seldom mentioned but at least as important;

    1) It will be very hard to get enough CO2 to warm the planet. And even if we manage to do that, the concentration of CO2 will be so high that it would be prohibitive for most earthly life, i.e. it would not be real terraforming.

    2) The biggest problem may be to get enough of an inert gas, on Earth nitrogen, N2. Most earthly life cannot live in a pure O2/CO2 atmosphere.

    Sigh, the gods haven’t made things easy for us: we do not have a second proper earth analogue in our solar system, not even a biocompatible or easily terraformable one.
    And we are not part of a binary system with the other star also having an earthlike planet.

    If one or both of these had been the case, this would have been an immense incentive for space travel since the ancient Greeks or at the latest the Renaissance, and we would probably already have established a presence there.

    1. Item 2 has actually been addressed in theoretical studies. Basically, scientists called for the importing of ammonia ices to help bolster a greenhouse effect, and then breaking the ammonia down into nitrogen gas. This can be done using terrestrial bacteria, specifically by Nitrosomonas(which convert ammonia in nitrites and nitrates) and Pseudomonas and Clostridium (which convert nitrates to nitrogen gas).

      1. Ok! So, scientific study has confirmed that there, indeed, isn’t nearly enough N on Mars.
        Ok then, let’s make a simple calculation: assuming 80% of the atmosphere as N2 and atmospheric pressure earthlike (1 atm.), and Mars having a surface area of 28.4% of earth, then we will need approx. 1.2 * 10^15 tonnes of N2 (or 1200 trillion tonnes).
        That’s an awful lot of N to import.

      2. Indeed it is, and so is the amount of CO2 that would need to be imported, not to mention the resources and infrastructure needed to get it all there. The point is, is it possible? Beyond that, we get into the sticky question of “how much are we willing to spend to get it done?”

  5. Hypothetical curiosity: if terraforming Mars were actually possible, how long would it take for the effects of imposed changes to result in a “green” Mars?

    1. Good question. I would estimate about 1000 years, and that’s a conservative guess. But since this would be a long-term plan, one which would be based on the idea that Earth might not be around forever, that doesn’t seem like too long a wait, right?

  6. Colonization and terraforming are two different concepts. The last few days I’ve been reading some version of this story and it is starting to bug me (i.e. the headline “Sorry Elon but you can’t terraform Mars” seems to be everywhere… since this would take 100s of year anyway why would Elon care?)

    There may not be enough local materials to make this a green planet with a warm atmosphere but there is nothing in the latest details to stop us from having colonies on Mars and supporting some population and life there (people would just be living in greenhouses or whatever instead of running around the surface without a spacesuit). Colonization is still a very possible and (remotely) probable thing.

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