One of the primary obstacles on the path to settling Mars is its frigid climate. A new study proposes addressing this issue by triggering a greenhouse effect.
Planetary scientists often liken Earth's perfect suitability for life to the story of Goldilocks and the Three Bears. In the tale, Goldilocks always chooses the option that feels "just right"—the soft bed that fits her perfectly, the chair that is neither too hard nor too soft, and the porridge that is neither too hot nor too cold. Similarly, Earth occupies a "just right" position in the solar system. It is at an ideal distance from the Sun—not too far like frozen Mars, nor too close like scorching Venus, where surface temperatures soar to around 400 degrees Celsius. This placement allows Earth's temperature to support liquid water—a fundamental requirement for life.
The stark unsuitability of Earth's neighboring planets for life has not deterred human imagination from envisioning cities and entire civilizations on their surfaces. Instead, the challenge of making these planets habitable inspires researchers and writers alike. Among them, the planet that captures most of the attention and is considered the leading candidate for habitability is Mars—often called the "Red Planet". Its relative proximity to Earth and certain similarities to our planet make it a prime focus. Yet, Mars is far from being an ideal candidate: it is a frigid world with an average temperature of -62 degrees Celsius and an extremely thin atmosphere. While evidence suggests that liquid water may have flowed on its surface in the distant past - about 600,000 years ago - today, this invaluable resource exists only at the icy poles or buried beneath the planet's surface.
In the distant past, liquid water may have flowed across Mars' surface, but today this precious resource is found only at the frozen poles or hidden beneath the surface. Ice at Mars’ northern polar cap | NASA/JPL-Caltech/MSSS
Artificial Heating
Despite all these challenges, a new study published in Science Advances suggests that the same mechanism responsible for warming Earth—the greenhouse effect—could be harnessed to warm Mars, potentially making it more suitable for human habitation. Mars contains vast amounts of dust grains formed from the weathering of iron-rich minerals. These grains are spherical, with an average radius of 1.5 microns (millionths of a meter). Their shape causes sunlight to scatter uniformly in all directions. As a result, when these particles rise to higher altitudes, they act like a sunshade, reflecting sunlight and cooling the planet instead of trapping heat at the surface.
The study proposes a novel approach: engineering Mars’ native dust particles to enhance their sunlight absorption, eliminating the need to "import" special dust particles from Earth for this purpose. The researchers developed a method to transform these spherical particles into rod-shaped ones using the same local minerals. These engineered particles, approximately twice the size of natural Mars dust grains and slightly smaller than glitter, were designed through simulations that accounted for the planet’s atmospheric winds, topography, and other factors.
Using an advanced simulation program called MarsWRF, which models the atmospheric conditions on Mars, the researchers evaluated the effects of these particles on radiation trapping. The results were remarkable: the engineered dust particles efficiently absorbed sunlight, raising Mars' surface temperatures by about 10 degrees Celsius within just a few months. Although the process would require around two million tons of these rod-shaped particles, the abundance of the materials on Mars makes the concept feasible.
In simulations, the engineered particles efficiently absorbed sunlight, raising Mars’ temperatures by about 10 degrees Celsius within months. Illustration of the method | Aaron M. Geller, Northwestern, Center for Interdisciplinary Exploration and Research in Astrophysics + IT-RCDS
Despite these promising findings, implementing such a global-scale engineering effort on Mars remains a distant prospect. Altering the planet’s environment on such a massive scale is an immensely complex and risky endeavor. Even if scientists could overcome the immediate obstacles, Mars presents significant additional challenges beyond its frigid temperatures. For instance, the Martian atmosphere contains only trace amounts of oxygen compared to Earth, and its atmospheric pressure is roughly 160 times lower than that on Earth. This extremely low pressure dramatically reduces the boiling point of liquids, including bodily fluids - meaning that without a pressurized space suit, exposure to such conditions could cause severe physiological effects, such as blood boiling.
Additionally, the amount of ultraviolet radiation on Mars is exceptionally high due to the absence of an ozone layer, posing a potentially lethal threat. Lastly, researchers raise the possibility that the Martian soil may be salty or toxic, presenting yet another obstacle to growing crops and sustaining life on the neighboring planet.
While the vision of warming Mars remains a distant goal, the study highlights a broader principle: by thoroughly understanding Earth’s processes—such as the greenhouse effect—innovative ideas can be developed for potential application on other planets.