Terraforming Mars: Can We Make the Red Planet be Earth-like?

Written By Edgar Salus

Terraforming is the theoretical process of modifying a planet to make it habitable for humans, and in recent years, there has been much discussion about terraforming Mars.

JPL-Caltech/NASA

Future in Space?

Future population growth and the demand for resources that cannot be easily managed on our planet may in the future require human colonization on celestial bodies other than Earth. Currently, no other planets in our solar system are habitable because life, as we know it, cannot survive anywhere else except Earth. However, for many years, Mars has existed as a hopeful Planet B if Earth can no longer support us as a species. Further, researchers have found evidence that Mars was habitable a very long time ago.  

Panoramic image, by NASA's Curiosity Mars rover on April 8, 2023, shows the "Marker Band Valley" colorized and at different times of day/ NASA

Challenges and Limitations 

In many respects, Mars is the most Earth-like of all of the other planets in the Solar System and, according to scientific research, Mars had a more Earth-like environment early in its geological history making it one of the most plausible terraforming targets in the Solar System. 

Similarities between Mars and Earth

There are a few similarities between these two planets, the main ones being: 

  • Water: Both Mars and Earth have water, but Mars only has patches of frozen water at its poles (especially the southern pole).

  • Rocky planets: Both Mars and Earth have a rocky surface and the total land of Mars is roughly identical in area to the total dry land on Earth. 

  • Length of day: In comparison to Earth’s roughly 24 hour-day, a day on Mars (known as Sol) lasts 24 hours and 37 minutes. Therefore, for anyone planning to live on Mars, it would not be hard to adjust to slightly longer days. 

Differences between Mars and Earth

The differences between Earth and Mars far outweigh the things these two planets have in common and these present real challenges to any inhabitation ideas for the red planet. The key differences are: 

  • Gravity: The surface gravity on Mars is only about 38% of that on Earth. It is not known if this is enough to prevent the health problems associated with weightlessness.

  • Atmosphere: The atmosphere of Mars is much too thin and cold to support liquid water on its surface. With an atmospheric pressure of around 0.6% of Earth’s, any surface water would quickly evaporate or freeze. Further, the Martian atmosphere is made up of 95% carbon dioxide, with only small traces of oxygen. 

  • Temperature:  Being further away from the Sun and a thinner atmosphere makes it much more difficult for Mars to maintain heat. Therefore the climate on Mars is significantly colder than on Earth. The average temperature on Mars is -63 degrees Celsius (-81 degrees Fahrenheit). In comparison, the average temperature on Earth is 16 degrees Celsius (61 degrees Fahrenheit). 

  • Magnetic Field: On Earth, the thick atmosphere protects against the harsh ultraviolet radiation from the Sun and it also acts as an insulator to maintain the warmer temperatures. Due to its smaller mass, Mars’ core cooled down about 4 billion years ago. Because of this, the magnetic field of Mars faded away, allowing for most of the planet’s atmosphere and surface water to be stripped away over millions of years. As a result, the atmosphere on Mars is not merely as effective as on Earth, blocking virtually no solar radiation and not keeping much heat in at all. 

The solar wind has played a key role in stripping Mars of its atmosphere (Supplied: NASA/GSFC)

Proposed Methods and Strategies

Terraforming Mars would entail three major aspects: 

  1. Implementing a new magnetic field

  2. Raising the temperature and atmospheric pressure of the red planet, and

  3. Making Mars’ atmosphere breathable.

There are different proposals on how these goals could be achieved: 

Implementing a Magnetic Field

NASA‘s MAVEN mission has revealed that Mars is losing its atmosphere and water even today. To avoid that any changes made to Mars are constantly reverted by the Sun‘s powerful influences and to truly terraform Mars, it would therefore be necessary to restore its magnetic field. 

NASA's plan to build a magnetic shield around Mars to protect its atmosphere (Supplied: NASA/Jim Green)

While we do not have the technology to churn the core of a planet faster to revive its magnetic field, NASA‘s Chief Scientist Dr. Jim Green and his colleagues have theorized about a large magnetic dipole placed at Mars‘ Lagrange point 1 (L1) between the Sun and Mars, where their gravitational forces roughly cancel out. This would enable the magnetic dipole to follow Mars as it orbits the Sun, constantly deflecting solar wind that would destroy any significant atmosphere. 

According to Green and his team, a magnetic field of 10,000 to 20,000 Gauss would be required to sufficiently shield Mars against the solar wind. Green also acknowledged that with current technology a magnetic field of about 2,000 Gauss could be installed at the Sun-Mars L1 pont. Therefore, undertaking the endeavor of restoring the Martian magnetic field is therefore not possible as of today. 


Raising the temperature and atmospheric pressure

There are several different schools of thought on how (or if) we could heat up Mars’ atmosphere and make it more hospitable to life. Generally, speaking, the two processes of building the atmosphere and heating the planet would augment each other, favoring terraforming. Some people  - including Elon Musk - have suggested that by exploding nuclear bombs over the polar caps on Mars, the heat would vaporize the frozen carbon dioxide and create greenhouse gasses 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. 

Apart from the ethical issues of nuking another planet, this plan would only be temporary. The carbon dioxide added to Mars’ atmosphere by vaporizing the polar caps would only double the pressure (to 1.2 percent of Earth’s) - not even close to the comparable pressure to Earth required for conditions warm enough to sustain surface liquid water and atmospheric water vapor. 

Mars’ southern polar ice sheets, shown here in images from NASA’s Mars Orbiter Camera on the Mars Global Surveyor spacecraft. GODDARD SPACE FLIGHT CENTER SCIENTIFIC VISUALIZATION STUDIO MARS ORBITER CAMERA DATA/NASA

Another proposal to release carbon dioxide into the atmosphere of Mars is through mining for and subsequently heating up carbon minerals such as calcite. The minerals would have to be heated up to a temperature of about 300 degrees Celsius (575 degrees Fahrenheit). To get the atmospheric pressure high enough to sustain the water’s liquid form, one would 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 only be about 10-14 percent of that of Earth. The corresponding average temperature rise that could be achieved through this would be about 10 degrees Celsius - not nearly enough to sustain liquid water. 

Finally, it has been suggested that if there was a fleet of spacecraft capable of redirecting ammonia-rich asteroids to collide with Mars, that could rapidly speed up the terraforming process. Asteroids with ammonia can be found in the asteroid belt, which sits between Mars and Jupiter. When these asteroids collide with Mars the ammonia will be broken into nitrogen and hydrogen gas, helping to thicken the atmosphere and warm the planet. However, it would require mass amounts of a very advanced and efficient spacecraft to direct the impacts and make any meaningful difference. That is not practical as of now. 

Breathing on Mars

Making Mars’ atmosphere breathable is another challenge. 

In 2021, the NASA Mars rover Perseverance was able to make oxygen on Mars. However, the process is complex and takes a considerable amount of time to produce a small amount of oxygen and doing this for the entire planet may not be feasible. This is why some researchers suggest turning to forms of life that have already transformed Earth’s atmosphere. On Earth, around 2.5 billion years ago, microorganisms called cyanobacteria were responsible for converting our atmosphere of methane, ammonia and other gasses into the oxygen-rich atmosphere of today. 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. 

Conclusion 

In short, it seems very unrealistic that transforming Mars into a more Earth-like planet can be achieved anytime soon. While we may reach Mars this century, it could take several millennia for the idea of terraforming to be implemented. In the meantime, future Martian explorers will need to live in enclosed structures on the surface or underground to keep warm and give them air to breathe.

Edgar Salus
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