The dream of humans living on Mars has been around for decades, and in recent years it has moved closer than ever to serious scientific and engineering conversations. But a new study published in APS Open Science Author: Slava Turyshev NASAJPL is a steadfast reminder that dreaming about the Red Planet and actually making it habitable are two very different things. According to Turishev’s calculations, transforming Mars into a world with breathable air, liquid water, and stable temperatures would require so much mass, heat, oxygen, and energy that the entire project is completely beyond humanity’s current industrial or technological capabilities, and is likely to remain that way for centuries to come.

Five stages of Mars terraforming and the requirements for each stage

Before we get into the numbers, let’s take a look at what terraforming Mars would actually entail in stages. Turishev’s research lists five distinct milestones on the path from today’s Mars to something like Earth.The starting point is Mars as we know it: a frigid planet with an atmosphere so thin that liquid water cannot be maintained on the surface and would kill a human within minutes if not wearing a pressurized suit. The first real milestone was raising atmospheric pressure above 6.1 millibars at 0°C, which is the triple point of water, the specific combination of temperature and pressure at which water can exist simultaneously as a solid, a liquid and a gas. Then there are what scientists call “pocket greenhouse” environments, where large pressurized domes could support agriculture across regions without the need for extreme engineering. This method, known as metaterraforming, involves creating enclosed habitable zones rather than transforming the entire planet at once.The fourth milestone will be when global surface pressure reaches 62.7 millibars, at which point human blood will no longer boil at body temperature on the surface of Mars. The ultimate goal is a fully breathable atmosphere: a total atmospheric pressure of about 500 millibars, an oxygen content of about 210 millibars, and temperatures high enough for liquid water to exist extensively and stably.

Why Mars needs an atmosphere equal to the mass of the entire Moon

Each stage sounds ambitious on its own, but the research makes the physical scale involved almost unmanageable. To raise the atmospheric pressure of Mars by one millibar, approximately 3.89 × 10^5 kg of gas would need to be added. This is roughly equivalent to the total mass of Deimos, the smaller of Mars’ two moons. Expanding it to the atmospheric pressure required for a breathable environment would require nearly 10^18 kilograms of material, comparable to that of Saturn’s irregular moon Janus.To be fair to those who believe terraforming is possible, hundreds of objects of this mass are expected to litter the outer solar system. In principle, it would not be physically impossible to sacrifice one of them to create a habitable atmosphere on Mars. But the engineering required to move or change direction dwarfs anything humans have ever attempted.

Temperature Issues and Mirror Sizes to Solve It

Atmospheric pressure is just one of two core planetary variables that need to be changed. Temperature is another. Today’s Mars is on average about 60°C cooler than the Earth’s surface, and liquid water exists stably on its surface. Various methods have been proposed to close this gap, from injecting short-wave-absorbing nanoparticles into the atmosphere to releasing large amounts of carbon dioxide as a greenhouse gas.One idea often floated by engineers is to install giant orbiting mirrors to focus extra sunlight onto Mars. According to Turishev’s calculations Publish a paperto do this effectively would require approximately 70 million square kilometers of mirror surface. For context, that’s larger than the entire surface area of ​​the Asian continent. There is no industrial base, no manufacturing pipeline, or launch capability anywhere in the world today to build anything remotely close to this scale.

Providing oxygen to the Martian atmosphere would require an ocean’s worth of water

Even if the atmosphere and temperature could somehow be addressed, the oxygen problem would add another layer of hard-to-absorb scale. Producing enough oxygen for a fully breathable Martian atmosphere would require the production of approximately 8.2 × 1017 kg of gas. The most practical method is to separate oxygen from water through electrolysis. Taking into account the hydrogen lost in the process, the amount of water required per square meter of the Martian surface would be about six cubic meters.As noted in the study, the surprisingly good news is that Mars actually has enough accessible surface ice to meet this requirement. All the water needed for oxygen alone consumes only about 20% of the known surface ice. This means that more extreme suggestions, such as crashing multiple water-bearing comets into Mars to establish its hydrosphere, may not be necessary. Mars has raw materials. It doesn’t have any way of processing it at the required rate.

Energy is the biggest obstacle to habitability on Mars

Of all the limitations Turishev points out, energy is the one that makes the timeline most sobering. The minimum energy required to break down enough water to produce the oxygen needed for the Martian atmosphere is about 1.2 × 10²⁵ Joules. Over a thousand years of continuous operation, meeting this requirement would require a sustained power output of approximately 380 terawatts. This number is almost 20 times the total annual energy consumption of every country on earth today.There is no feasible way to generate this power in the short term. Humanity’s current civilization simply cannot operate on such an energy scale, and getting there will require advances in energy production that, even under optimistic assumptions, may take centuries.The gap left by this research is the long-term perspective. Future civilizations, operating with energy and industrial capabilities that do not yet exist, may find some of these numbers easier to manage. The solar system does contain the raw materials needed for Mars. The physics that turn these materials into a habitable atmosphere do, in principle, work. The gap is entirely one of capabilities, not concepts, and the gap, while huge by current standards, can, at least in theory, be reduced by technological advances long enough. For now, though, Mars remains what it always has been: a compelling destination for exploration that’s still a long way from becoming a second home.