The idea of transforming Mars into a world more hospitable to human habitation is a regular feature of science fiction. But can this be done in real life?
Scientists are now proposing a new approach to warming Earth’s planetary neighbor by pumping engineered particles — similar in size to commercially available glitter and made of iron or aluminum — into the atmosphere as aerosols to trap the escaping heat and to scatter sunlight towards the surface of Mars. The idea would be to add to the natural greenhouse effect on Mars to raise its surface temperature by roughly 50 degrees Fahrenheit (28 degrees Celsius) over the course of a decade.
That alone wouldn’t make Mars habitable for humans, but the scientists who developed the proposal see it as a potentially feasible first step.
“Terraforming refers to modifying a planet’s environment to make it more Earth-like. For Mars, warming the planet is a necessary but insufficient first step. Previous concepts have focused on the release of greenhouse gases, but these require large amounts of resources that are scarce on Mars,” said University of Chicago planetary scientist Edwin Kite, who helped lead the study published this week in the journal Science Advances.
“Key elements of our paper are a new proposal to use engineered nanoparticles to heat the Martian atmosphere and climate modeling that suggests this approach could be much more efficient than previous concepts. This is important because it presents a potentially more feasible method for modifying the Martian climate, which could inform future Martian exploration strategies,” Kite added.
NASA has sent robotic rovers to explore the surface of Mars and the InSight Lander to study the planet’s interior. The US space agency’s Artemis program aims to put astronauts on the lunar surface in the coming years for the first time since 1972 in preparation for future human missions to Mars.
There are many challenges to human settlements on Mars: lack of breathable oxygen, harmful ultraviolet radiation due to its thin atmosphere, salty soil hostile to growing crops, dust storms that sometimes cover much of of the planet and more. But its cold temperatures are a serious drawback.
“We propose to show that the idea of warming Mars is not impossible. We hope our finding will encourage the broader scientific community and the public to explore this intriguing idea,” said lead study author Samaneh Ansari, a doctoral student in the department of electrical and computer engineering at Northwestern University in Illinois.
The average surface temperature of Mars is about minus-85 degrees Fahrenheit (minus-65 degrees Celsius). With its thin atmosphere, solar heat on the surface of Mars easily escapes into space. The proposal would aim to allow liquid water to exist on the surface of Mars, which has water in the form of ice in its polar regions and beneath its surface.
Scientists proposed the continuous release of tiny rod-shaped particles — nanorods — into the atmosphere at a rate of about eight gallons (30 liters) per second for years.
“The idea is to either send the material or better yet, send the manufacturing tool and produce the nanorods to the planet since iron and aluminum are abundant on the surface of Mars,” Ansari said.
Researchers are aware of the possibility of unintended consequences in terraforming another world for the benefit of humanity. Scientists, for example, are eager to learn whether Mars harbored life in the past — or perhaps currently, in the form of subterranean microbes.
“Although nanoparticles could warm Mars, both the potential benefits and costs of this course of action are currently uncertain. For example, in the unlikely event that Martian soil contains irreparably toxic compounds for all Earth-derived life, then the benefit of warming Mars is zero,” Kite said.
“On the other hand, if a photosynthetic biosphere can be established on the surface of Mars, this could increase the capacity of the solar system for human flourishing,” Kite added. “On the cost side, if Mars has extant life, then studying that life could have huge benefits that warrant robust protection for its habitat.”